http://ift.tt/2qbcOd8
Cancer Medicine by Alexandros G.Sfakianakis,Anapafseos 5 Agios Nikolaos,Crete 72100,Greece,tel :00302841026182 & 00306932607174
Δευτέρα 1 Ιανουαρίου 2018
Skin cancer rates in North Rhine-Westphalia, Germany before and after the introduction of the nationwide skin cancer screening program (2000–2015)
Abstract
Germany is the first nation that implemented a nationwide skin cancer screening program in 2008. The aim is to study the effect of the program on skin cancer rates and to estimate the number needed to screen for an unselected and a hypothetical high-risk population in Germany. We used population-based data on skin cancer incidence (2000–2014), mortality, hospitalization and sick leave (2000–2015) from North Rhine-Westphalia, Germany (18 million population). We calculated annual age-standardized rates per 100,000 person years and calculated the relative change of the rates (%) including 95% confidence intervals (95% CI). Between 2007 and 2014, the estimated annual percentage change (EAPC) of the age-standardized incidence rate of skin melanoma was 3.8% among men and women. These increases were accompanied by increases of the age-standardized mortality rates (EAPC men 3.2%, women 2.0%) and age-standardized sick leave rates (EAPC men 11.0%, women 6.1%). Hospitalization rates showed barely any change. All types of rates for nonmelanoma skin cancer showed marked increases. The number needed to screen for skin melanoma death would be 34,000 if the risk reduction due to screening would be 50%. In a hypothetical high-risk approach with 10% of the population at high risk, that is, a relative risk of melanoma death of 4.0, a skin melanoma mortality risk reduction of 50% among these people due to screening would result in a reduction of the skin melanoma mortality by 15% in the total population. However, this reduction would require a number needed to screen of 11,141. Seven years after the introduction of the skin cancer screening program, there is no discernible beneficial effect at population level. The estimated number needed to screen for skin melanoma in an unselected approach is high and a realistic high-risk approach is currently not feasible.
from Cancer via ola Kala on Inoreader http://ift.tt/2DOmvAu
via IFTTT
Hypothetical interventions to prevent stroke: an application of the parametric g-formula to a healthy middle-aged population
Abstract
The effects of interventions on multiple lifestyle and metabolic risk factors, initiated in midlife or later in a healthy population, on the long-term risk of first-ever stroke is not known. A particular methodological challenge in observational studies is to estimate the unbiased effect of a time-varying exposure in presence of time-varying confounders, if those confounders are affected by prior exposure. In such cases, the parametric g-formula can be applied to estimate an unbiased effect. We applied the parametric g-formula to estimate the 18-years (1994–2012) cumulative stroke risk under different scenarios of hypothetical interventions on levels of blood pressure, cholesterol, weight, physical activity, smoking and alcohol intake; and compared these to the observed scenario, to calculate the population risk ratios and risk differences. Among 14,796 eligible participants in the prospective, population-based Tromsø study (baseline mean age 46.1 years, 51% women), the observed 18-years stroke risk was 5.9%. A feasible joint hypothetical intervention on six lifestyle and metabolic risk factors would reduce the 18-year stroke risk by 32% (95% confidence interval 16, 44). A combination of more intensive interventions reduced the estimated 18-years stroke risk by 64% (95% confidence interval 40, 80). Blood pressure reduction and quitting smoking significantly reduced the risk when applied separately.
from Cancer via ola Kala on Inoreader http://ift.tt/2CEG4LS
via IFTTT
Skin cancer rates in North Rhine-Westphalia, Germany before and after the introduction of the nationwide skin cancer screening program (2000–2015)
Abstract
Germany is the first nation that implemented a nationwide skin cancer screening program in 2008. The aim is to study the effect of the program on skin cancer rates and to estimate the number needed to screen for an unselected and a hypothetical high-risk population in Germany. We used population-based data on skin cancer incidence (2000–2014), mortality, hospitalization and sick leave (2000–2015) from North Rhine-Westphalia, Germany (18 million population). We calculated annual age-standardized rates per 100,000 person years and calculated the relative change of the rates (%) including 95% confidence intervals (95% CI). Between 2007 and 2014, the estimated annual percentage change (EAPC) of the age-standardized incidence rate of skin melanoma was 3.8% among men and women. These increases were accompanied by increases of the age-standardized mortality rates (EAPC men 3.2%, women 2.0%) and age-standardized sick leave rates (EAPC men 11.0%, women 6.1%). Hospitalization rates showed barely any change. All types of rates for nonmelanoma skin cancer showed marked increases. The number needed to screen for skin melanoma death would be 34,000 if the risk reduction due to screening would be 50%. In a hypothetical high-risk approach with 10% of the population at high risk, that is, a relative risk of melanoma death of 4.0, a skin melanoma mortality risk reduction of 50% among these people due to screening would result in a reduction of the skin melanoma mortality by 15% in the total population. However, this reduction would require a number needed to screen of 11,141. Seven years after the introduction of the skin cancer screening program, there is no discernible beneficial effect at population level. The estimated number needed to screen for skin melanoma in an unselected approach is high and a realistic high-risk approach is currently not feasible.
http://ift.tt/2DOmvAu
Hypothetical interventions to prevent stroke: an application of the parametric g-formula to a healthy middle-aged population
Abstract
The effects of interventions on multiple lifestyle and metabolic risk factors, initiated in midlife or later in a healthy population, on the long-term risk of first-ever stroke is not known. A particular methodological challenge in observational studies is to estimate the unbiased effect of a time-varying exposure in presence of time-varying confounders, if those confounders are affected by prior exposure. In such cases, the parametric g-formula can be applied to estimate an unbiased effect. We applied the parametric g-formula to estimate the 18-years (1994–2012) cumulative stroke risk under different scenarios of hypothetical interventions on levels of blood pressure, cholesterol, weight, physical activity, smoking and alcohol intake; and compared these to the observed scenario, to calculate the population risk ratios and risk differences. Among 14,796 eligible participants in the prospective, population-based Tromsø study (baseline mean age 46.1 years, 51% women), the observed 18-years stroke risk was 5.9%. A feasible joint hypothetical intervention on six lifestyle and metabolic risk factors would reduce the 18-year stroke risk by 32% (95% confidence interval 16, 44). A combination of more intensive interventions reduced the estimated 18-years stroke risk by 64% (95% confidence interval 40, 80). Blood pressure reduction and quitting smoking significantly reduced the risk when applied separately.
http://ift.tt/2CEG4LS
Skin cancer rates in North Rhine-Westphalia, Germany before and after the introduction of the nationwide skin cancer screening program (2000–2015)
Abstract
Germany is the first nation that implemented a nationwide skin cancer screening program in 2008. The aim is to study the effect of the program on skin cancer rates and to estimate the number needed to screen for an unselected and a hypothetical high-risk population in Germany. We used population-based data on skin cancer incidence (2000–2014), mortality, hospitalization and sick leave (2000–2015) from North Rhine-Westphalia, Germany (18 million population). We calculated annual age-standardized rates per 100,000 person years and calculated the relative change of the rates (%) including 95% confidence intervals (95% CI). Between 2007 and 2014, the estimated annual percentage change (EAPC) of the age-standardized incidence rate of skin melanoma was 3.8% among men and women. These increases were accompanied by increases of the age-standardized mortality rates (EAPC men 3.2%, women 2.0%) and age-standardized sick leave rates (EAPC men 11.0%, women 6.1%). Hospitalization rates showed barely any change. All types of rates for nonmelanoma skin cancer showed marked increases. The number needed to screen for skin melanoma death would be 34,000 if the risk reduction due to screening would be 50%. In a hypothetical high-risk approach with 10% of the population at high risk, that is, a relative risk of melanoma death of 4.0, a skin melanoma mortality risk reduction of 50% among these people due to screening would result in a reduction of the skin melanoma mortality by 15% in the total population. However, this reduction would require a number needed to screen of 11,141. Seven years after the introduction of the skin cancer screening program, there is no discernible beneficial effect at population level. The estimated number needed to screen for skin melanoma in an unselected approach is high and a realistic high-risk approach is currently not feasible.
from Cancer via ola Kala on Inoreader http://ift.tt/2DOmvAu
via IFTTT
Hypothetical interventions to prevent stroke: an application of the parametric g-formula to a healthy middle-aged population
Abstract
The effects of interventions on multiple lifestyle and metabolic risk factors, initiated in midlife or later in a healthy population, on the long-term risk of first-ever stroke is not known. A particular methodological challenge in observational studies is to estimate the unbiased effect of a time-varying exposure in presence of time-varying confounders, if those confounders are affected by prior exposure. In such cases, the parametric g-formula can be applied to estimate an unbiased effect. We applied the parametric g-formula to estimate the 18-years (1994–2012) cumulative stroke risk under different scenarios of hypothetical interventions on levels of blood pressure, cholesterol, weight, physical activity, smoking and alcohol intake; and compared these to the observed scenario, to calculate the population risk ratios and risk differences. Among 14,796 eligible participants in the prospective, population-based Tromsø study (baseline mean age 46.1 years, 51% women), the observed 18-years stroke risk was 5.9%. A feasible joint hypothetical intervention on six lifestyle and metabolic risk factors would reduce the 18-year stroke risk by 32% (95% confidence interval 16, 44). A combination of more intensive interventions reduced the estimated 18-years stroke risk by 64% (95% confidence interval 40, 80). Blood pressure reduction and quitting smoking significantly reduced the risk when applied separately.
from Cancer via ola Kala on Inoreader http://ift.tt/2CEG4LS
via IFTTT
JQ1 Induces DNA Damage and Apoptosis, and Inhibits Tumor Growth in a Patient-Derived Xenograft Model of Cholangiocarcinoma
Cholangiocarcinoma (CCA) is a fatal disease with a 5-year survival of <30%. For a majority of patients, chemotherapy is the only therapeutic option, and virtually all patients relapse. Gemcitabine is the first-line agent for treatment of CCA. Patients treated with gemcitabine monotherapy survive ~8 months. Combining this agent with cisplatin increases survival by ~3 months, but neither regimen produces durable remissions. The molecular etiology of this disease is poorly understood. To facilitate molecular characterization and development of effective therapies for CCA, we established a panel of patient-derived xenograft (PDX) models of CCA. We used two of these models to investigate the antitumor efficacy and mechanism of action of the bromodomain inhibitor JQ1, an agent that has not been evaluated for the treatment of CCA. The data show that JQ1 suppressed the growth of the CCA PDX model CCA2 and demonstrate that growth suppression was concomitant with inhibition of c-Myc protein expression. A second model (CCA1) was JQ1-insensitive, with tumor progression and c-Myc expression unaffected by exposure to this agent. Also selective to CCA2 tumors, JQ1 induced DNA damage and apoptosis and downregulated multiple c-Myc transcriptional targets that regulate cell-cycle progression and DNA repair. These findings suggest that c-Myc inhibition and several of its transcriptional targets may contribute to the mechanism of action of JQ1 in this tumor type. We conclude that BET inhibitors such as JQ1 warrant further investigation for the treatment of CCA. Mol Cancer Ther; 17(1); 107–18. ©2017 AACR.
from Cancer via ola Kala on Inoreader http://ift.tt/2qajkB9
via IFTTT
A Novel Therapeutic Strategy for Pancreatic Cancer: Targeting Cell Surface Glycan Using rBC2LC-N Lectin-Drug Conjugate (LDC)
Various cancers, including pancreatic ductal adenocarcinoma (PDAC), remain intractable even with costly tumor-targeting antibody drugs. Because the outermost coatings of cancer cells are composed of cell-specific glycan layers (glycocalyx), lectins, proteins with glycan-binding potential, were evaluated for possible use as drug carriers in PDAC treatment. A human PDAC cell line with well-to-moderately differentiated properties (Capan-1) was subjected to lectin microarray analysis to identify specific lectin–glycan pairs. The selected lectin was fused with a bacterial exotoxin for the construction of a lectin–drug conjugate (LDC), and its safety and antitumor effects were evaluated. A specific affinity between a recombinant bacterial C-type lectin (rBC2LC-N) and Capan-1 was identified, and its positivity was confirmed in 69 human samples. In contrast to the belief that all lectins mediate harmful hemagglutination, rBC2LC-N did not cause hemagglutination with human erythrocytes and was safely administered to mice. The 50% inhibitory concentration of LDC to Capan-1 (1.04 pg/mL = 0.0195 pmol/L) was 1/1,000 lower than that reported for conventional immunotoxins. The intraperitoneal administration of LDC reduced the tumor weight from 390 to 130.8 mg (P < 0.01) in an orthotopic model and reduced the number of nodules from 48 to 3 (P < 0.001) and improved survival from 62 to 105 days in a peritoneal dissemination model (P < 0.0001). In addition, the effect of LDC was reproduced in nodules from patient-derived PDAC xenografts through intravenous injection. Herein, we show the concept of utilizing lectins as drug carriers to target glycans on the cancer cell surface, highlighting new insights into cancer treatments. Mol Cancer Ther; 17(1); 183–95. ©2017 AACR.
from Cancer via ola Kala on Inoreader http://ift.tt/2lD1rGl
via IFTTT
Selective and Concentrated Accretion of SN-38 with a CEACAM5-Targeting Antibody-Drug Conjugate (ADC), Labetuzumab Govitecan (IMMU-130)
Labetuzumab govitecan (IMMU-130), an antibody–drug conjugate (ADC) with an average of 7.6 SN-38/IgG, was evaluated for its potential to enhance delivery of SN-38 to human colonic tumor xenografts. Mice bearing LS174T or GW-39 human colonic tumor xenografts were injected with irinotecan or IMMU-130 (SN-38 equivalents ~500 or ~16 μg, respectively). Serum and homogenates of tumors, liver, and small intestine were extracted, and SN-38, SN-38G (glucuronidated SN-38), and irinotecan concentrations determined by reversed-phase HPLC. Irinotecan cleared quickly from serum, with only 1% to 2% injected dose/mL after 5 minutes; overall, approximately 20% was converted to SN-38 and SN-38G. At 1 hour with IMMU-130, 45% to 63% injected dose/mL of the SN-38 was in the serum, with >90% bound to the ADC over 3 days, and with low levels of SN-38G. Total SN-38 levels decreased more quickly than the IgG, confirming a gradual SN-38 release from the ADC. AUC analysis found that SN-38 levels were approximately 11- and 16-fold higher in LS174T and GW-39 tumors, respectively, in IMMU-130–treated animals. This delivery advantage is amplified >30-fold when normalized to SN-38 equivalents injected for each product. Levels of SN-38 and SN-38G were appreciably lower in the liver and small intestinal contents in animals given IMMU-130. On the basis of the SN-38 equivalents administered, IMMU-130 potentially delivers >300-fold more SN-38 to CEA-producing tumors compared with irinotecan, while also reducing levels of SN-38 and SN-38G in normal tissues. These observations are consistent with preclinical and clinical data showing efficacy and improved safety. Mol Cancer Ther; 17(1); 196–203. ©2017 AACR.
from Cancer via ola Kala on Inoreader http://ift.tt/2qeTfR8
via IFTTT
Targeting Phosphatidylserine with Calcium-Dependent Protein-Drug Conjugates for the Treatment of Cancer
In response to cellular stress, phosphatidylserine is exposed on the outer membrane leaflet of tumor blood vessels and cancer cells, motivating the development of phosphatidylserine-specific therapies. The generation of drug-conjugated phosphatidylserine-targeting agents represents an unexplored therapeutic approach, for which antitumor effects are critically dependent on efficient internalization and lysosomal delivery of the cytotoxic drug. In the current study, we have generated phosphatidylserine-targeting agents by fusing phosphatidylserine-binding domains to a human IgG1-derived Fc fragment. The tumor localization and pharmacokinetics of several phosphatidylserine-specific Fc fusions have been analyzed in mice and demonstrate that Fc-Syt1, a fusion containing the synaptotagmin 1 C2A domain, effectively targets tumor tissue. Conjugation of Fc-Syt1 to the cytotoxic drug monomethyl auristatin E results in a protein–drug conjugate (PDC) that is internalized into target cells and, due to the Ca2+ dependence of phosphatidylserine binding, dissociates from phosphatidylserine in early endosomes. The released PDC is efficiently delivered to lysosomes and has potent antitumor effects in mouse xenograft tumor models. Interestingly, although an engineered, tetravalent Fc-Syt1 fusion shows increased binding to target cells, this higher avidity variant demonstrates reduced persistence and therapeutic effects compared with bivalent Fc-Syt1. Collectively, these studies show that finely tuned, Ca2+-switched phosphatidylserine-targeting agents can be therapeutically efficacious. Mol Cancer Ther; 17(1); 169–82. ©2017 AACR.
from Cancer via ola Kala on Inoreader http://ift.tt/2qb0mua
via IFTTT
Comparative Oncology Evaluation of Intravenous Recombinant Oncolytic Vesicular Stomatitis Virus Therapy in Spontaneous Canine Cancer
Clinical translation of intravenous therapies to treat disseminated or metastatic cancer is imperative. Comparative oncology, the evaluation of novel cancer therapies in animals with spontaneous cancer, can be utilized to inform and accelerate clinical translation. Preclinical murine studies demonstrate that single-shot systemic therapy with a vesicular stomatitis virus (VSV)-IFNβ-NIS, a novel recombinant oncolytic VSV, can induce curative remission in tumor-bearing mice. Clinical translation of VSV-IFNβ-NIS therapy is dependent on comprehensive assessment of clinical toxicities, virus shedding, pharmacokinetics, and efficacy in clinically relevant models. Dogs spontaneously develop cancer with comparable etiology, clinical progression, and response to therapy as human malignancies. A comparative oncology study was carried out to investigate feasibility and tolerability of intravenous oncolytic VSV-IFNβ-NIS therapy in pet dogs with spontaneous cancer. Nine dogs with various malignancies were treated with a single intravenous dose of VSV-IFNβ-NIS. Two dogs with high-grade peripheral T-cell lymphoma had rapid but transient remission of disseminated disease and transient hepatotoxicity that resolved spontaneously. There was no shedding of infectious virus. Correlative pharmacokinetic studies revealed elevated levels of VSV RNA in blood in dogs with measurable disease remission. This is the first evaluation of intravenous oncolytic virus therapy for spontaneous canine cancer, demonstrating that VSV-IFNβ-NIS is well-tolerated and safe in dogs with advanced or metastatic disease. This approach has informed clinical translation, including dose and target indication selection, leading to a clinical investigation of intravenous VSV-IFNβ-NIS therapy, and provided preliminary evidence of clinical efficacy and potential biomarkers that correlate with therapeutic response. Mol Cancer Ther; 17(1); 316–26. ©2017 AACR.
from Cancer via ola Kala on Inoreader http://ift.tt/2lBILGT
via IFTTT
Evaluation of CDK12 Protein Expression as a Potential Novel Biomarker for DNA Damage Response-Targeted Therapies in Breast Cancer
Disruption of Cyclin-Dependent Kinase 12 (CDK12) is known to lead to defects in DNA repair and sensitivity to platinum salts and PARP1/2 inhibitors. However, CDK12 has also been proposed as an oncogene in breast cancer. We therefore aimed to assess the frequency and distribution of CDK12 protein expression by IHC in independent cohorts of breast cancer and correlate this with outcome and genomic status. We found that 21% of primary unselected breast cancers were CDK12 high, and 10.5% were absent, by IHC. CDK12 positivity correlated with HER2 positivity but was not an independent predictor of breast cancer–specific survival taking HER2 status into account; however, absent CDK12 protein expression significantly correlated with a triple-negative phenotype. Interestingly, CDK12 protein absence was associated with reduced expression of a number of DDR proteins including ATR, Ku70/Ku80, PARP1, DNA-PK, and H2AX, suggesting a novel mechanism of CDK12-associated DDR dysregulation in breast cancer. Our data suggest that diagnostic IHC quantification of CDK12 in breast cancer is feasible, with CDK12 absence possibly signifying defective DDR function. This may have important therapeutic implications, particularly for triple-negative breast cancers. Mol Cancer Ther; 17(1); 306–15. ©2017 AACR.
from Cancer via ola Kala on Inoreader http://ift.tt/2qcIJdf
via IFTTT
"Wnt/{beta}-Catenin in GIST"--Letter
In an article published on September, 2017, in Molecular Cancer Therapeutics, Zeng and colleagues showed that the WNT/β-catenin oncogenic pathway was activated in a subset of human gastrointestinal stromal tumors (GIST) and that inhibiting its signaling alone or in combination with imatinib has antitumor efficacy in vitro and in vivo in imatinib-sensitive and resistant preclinical models. However, they concluded that "more investigation is needed to correlate β-catenin activation with clinicopathologic features in GIST clinical samples." Here, we examined the activation score of the β-catenin pathway in 160 clinically annotated clinical samples of operated primary GISTs. We showed that the β-catenin activation score, assessed as continuous variable, was heterogeneous across samples. Higher score was associated with certain prognostic clinicopathologic characteristics, including mutational status, tumor size, and AFIP classification, and even more importantly, with more postoperative relapses in uni- and multivariate analyses. Such unfavorable independent prognostic value of β-catenin activation reinforces the potential therapeutic value of this new target in GIST and nicely complements Zeng's study. Mol Cancer Ther; 17(1); 327–8. ©2018 AACR.
from Cancer via ola Kala on Inoreader http://ift.tt/2lCnn4x
via IFTTT
Clinical Application of Circulating Tumor DNA in the Genetic Analysis of Patients with Advanced GIST
Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumor of digestive tract. In the past, tissue biopsy was the main method for the diagnosis of GISTs. Although, circulating tumor DNA (ctDNA) detection by next-generation sequencing (NGS) may be a feasible and replaceable method for diagnosis of GISTs. We retrospectively analyzed the data for ctDNA and tissue DNA detection from 32 advanced GIST patients. We found that NGS obviously increased the positive rate of ctDNA detection. ctDNA detection identified rare mutations that were not detected in tissue DNA detection. Tumor size and Ki-67 were significant influencing factors of the positive rate of ctDNA detection and concordance between ctDNA and tissue DNA detection. In all patients, the concordance rate between ctDNA and tissue DNA detection was 71.9%, with moderate concordance, but the concordance was strong for patients with tumor size > 10 cm or Ki-67 > 5%. Tumor size, mitotic figure, Ki-67, and ctDNA mutation type were the significant influencing factors of prognosis, but only tumor size and ctDNA mutation type, were the independent prognostic factors for advanced GIST patients. We confirmed that ctDNA detection by NGS is a feasible and promising method for the diagnosis and prognosis of advanced GIST patients. Mol Cancer Ther; 17(1); 290–6. ©2017 AACR.
from Cancer via ola Kala on Inoreader http://ift.tt/2q92ySN
via IFTTT
CCL26 Participates in the PRL-3-Induced Promotion of Colorectal Cancer Invasion by Stimulating Tumor-Associated Macrophage Infiltration
Both phosphatase of regenerating liver-3 (PRL-3) and tumor-associated macrophages (TAM) influence cancer progression. Whether PRL-3 plays a critical role in colorectal cancer invasion and metastasis by inducing TAM infiltration remains unclear. In the current study, we investigated the effects of chemokine ligand 26 (CCL26) on TAM infiltration and colorectal cancer invasion and the underlying mechanism in colorectal cancer cells by overexpressing or silencing PRL-3. We found that PRL-3 upregulated CCL26 expression correlatively and participated in cell migration, according to the results of gene ontology analysis. In addition, IHC analysis results indicated that the PRL-3 and CCL26 levels were positively correlated and elevated in stage III and IV colorectal cancer tissues and were associated with a worse prognosis in colorectal cancer patients. Furthermore, we demonstrated that CCL26 induced TAM infiltration by CCL26 binding to the CCR3 receptor. When LoVo-P and HT29-C cells were cocultured with TAMs, CCL26 binding to the CCR3 receptor enhanced the invasiveness of LoVo-P and HT29-C cells by mobilizing intracellular Ca2+of TAMs to increase the expression of IL6 and IL8. In addition, IHC results indicated that protein levels of CCR3 and TAMs counts were higher in stage III and IV colorectal cancer tissues and correlated with CCL26. Moreover, similar results were observed in vivo using mice injected with LoVo-P and HT29-C cells. These data indicate that PRL-3 may represent a potential prognostic marker that promotes colorectal cancer invasion and metastasis by upregulating CCL26 to induce TAM infiltration. Mol Cancer Ther; 17(1); 276–89. ©2017 AACR.
from Cancer via ola Kala on Inoreader http://ift.tt/2lBKifZ
via IFTTT
The Mutational Landscape of Gastrointestinal Malignancies as Reflected by Circulating Tumor DNA
We aimed to assess the utility of a novel, noninvasive method of detecting genomic alterations in patients with gastrointestinal malignancies, i.e., the use of liquid biopsies to obtain blood-derived circulating tumor DNA (ctDNA) through an analysis of the genomic landscape of ctDNA (68 genes) from 213 patients with advanced gastrointestinal cancers. The most common cancer types were colorectal adenocarcinoma (N = 55; 26%), appendiceal adenocarcinoma (N = 46; 22%), hepatocellular carcinoma (N = 31; 15%), and pancreatic ductal adenocarcinoma (N = 25; 12%). The majority of patients (58%) had ≥1 characterized alteration (excluded variants of unknown significance). The median number of characterized alterations was 1 (range, 0–13). The number of detected alterations per patient varied between different cancer types: in hepatocellular carcinoma, 74% of patients (23/31) had ≥1 characterized alteration(s) versus 24% of appendiceal adenocarcinoma patients (11/46). The median percent ctDNA among characterized alterations was 2.50% (interquartile range, 0.76%–8.96%). Overall, 95% of patients (117/123) had distinct molecular portfolios with 143 unique characterized alterations within 56 genes. Overall, concordance rates of 96%, 94%, 95%, and 91%, respectively, were found between ctDNA and tissue biopsy (N = 105 patients) in the four most common alterations (KRAS amplification, MYC amplification, KRAS G12V, and EGFR amplification). Of 123 patients with characterized alterations, >99% (122/123; 57% of entire population tested; 122/213) had one or more alterations potentially actionable by experimental or approved drugs. These observations suggest that many patients with gastrointestinal tumors, including difficult-to-biopsy malignancies like hepatocellular cancers, frequently have discernible and theoretically pharmacologically tractable ctDNA alterations that merit further studies in prospective trials. Mol Cancer Ther; 17(1); 297–305. ©2017 AACR.
from Cancer via ola Kala on Inoreader http://ift.tt/2qgWxDR
via IFTTT
AKT1low Quiescent Cancer Cells Promote Solid Tumor Growth
Human tumor growth depends on rapidly dividing cancer cells driving population expansion. Even advanced tumors, however, contain slowly proliferating cancer cells for reasons that remain unclear. Here, we selectively disrupt the ability of rapidly proliferating cancer cells to spawn AKT1low daughter cells that are rare, slowly proliferating, tumor-initiating, and chemotherapy-resistant, using β1-integrin activation and the AKT1-E17K–mutant oncoprotein as experimental tools in vivo. Surprisingly, we find that selective depletion of AKT1low slow proliferators actually reduces the growth of a molecularly diverse panel of human cancer cell xenograft models without globally altering cell proliferation or survival in vivo. Moreover, we find that unusual cancer patients with AKT1-E17K–mutant solid tumors also fail to produce AKT1low quiescent cancer cells and that this correlates with significantly prolonged survival after adjuvant treatment compared with other patients. These findings support a model whereby human solid tumor growth depends on not only rapidly proliferating cancer cells but also on the continuous production of AKT1low slow proliferators. Mol Cancer Ther; 17(1); 254–63. ©2017 AACR.
from Cancer via ola Kala on Inoreader http://ift.tt/2lBKbB5
via IFTTT
Caveolae-Mediated Endocytosis as a Novel Mechanism of Resistance to Trastuzumab Emtansine (T-DM1)
Trastuzumab emtansine (T-DM1) is an antibody–drug conjugate (ADC) that has demonstrated clinical benefit for patients with HER2+ metastatic breast cancer; however, its clinical activity is limited by inherent or acquired drug resistance. The molecular mechanisms that drive clinical resistance to T-DM1, especially in HER2+ tumors, are not well understood. We used HER2+ cell lines to develop models of T-DM1 resistance using a cyclical dosing schema in which cells received T-DM1 in an "on-off" routine until a T-DM1–resistant population was generated. T-DM1–resistant N87 cells (N87-TM) were cross-resistant to a panel of trastuzumab-ADCs (T-ADCs) with non–cleavable-linked auristatins. N87-TM cells do not have a decrease in HER2 protein levels or an increase in drug transporter protein (e.g., MDR1) expression compared with parental N87 cells. Intriguingly, T-ADCs using auristatin payloads attached via an enzymatically cleavable linker overcome T-DM1 resistance in N87-TM cells. Importantly, N87-TM cells implanted into athymic mice formed T-DM1 refractory tumors that remain sensitive to T-ADCs with cleavable-linked auristatin payloads. Comparative proteomic profiling suggested enrichment in proteins that mediate caveolae formation and endocytosis in the N87-TM cells. Indeed, N87-TM cells internalize T-ADCs into intracellular caveolin-1 (CAV1)–positive puncta and alter their trafficking to the lysosome compared with N87 cells. T-DM1 colocalization into intracellular CAV1-positive puncta correlated with reduced response to T-DM1 in a panel of HER2+ cell lines. Together, these data suggest that caveolae-mediated endocytosis of T-DM1 may serve as a novel predictive biomarker for patient response to T-DM1. Mol Cancer Ther; 17(1); 243–53. ©2017 AACR.
from Cancer via ola Kala on Inoreader http://ift.tt/2qb4jyJ
via IFTTT
Metabolite Profiling Reveals the Glutathione Biosynthetic Pathway as a Therapeutic Target in Triple-Negative Breast Cancer
Cancer cells can exhibit altered dependency on specific metabolic pathways and targeting these dependencies is a promising therapeutic strategy. Triple-negative breast cancer (TNBC) is an aggressive and genomically heterogeneous subset of breast cancer that is resistant to existing targeted therapies. To identify metabolic pathway dependencies in TNBC, we first conducted mass spectrometry–based metabolomics of TNBC and control cells. Relative levels of intracellular metabolites distinguished TNBC from nontransformed breast epithelia and revealed two metabolic subtypes within TNBC that correlate with markers of basal-like versus non-basal–like status. Among the distinguishing metabolites, levels of the cellular redox buffer glutathione were lower in TNBC cell lines compared to controls and markedly lower in non-basal–like TNBC. Significantly, these cell lines showed enhanced sensitivity to pharmacologic inhibition of glutathione biosynthesis that was rescued by N-acetylcysteine, demonstrating a dependence on glutathione production to suppress ROS and support tumor cell survival. Consistent with this, patients whose tumors express elevated levels of -glutamylcysteine ligase, the rate-limiting enzyme in glutathione biosynthesis, had significantly poorer survival. We find, further, that agents that limit the availability of glutathione precursors enhance both glutathione depletion and TNBC cell killing by -glutamylcysteine ligase inhibitors in vitro. Importantly, we demonstrate the ability to this approach to suppress glutathione levels and TNBC xenograft growth in vivo. Overall, these findings support the potential of targeting the glutathione biosynthetic pathway as a therapeutic strategy in TNBC and identify the non-basal-like subset as most likely to respond. Mol Cancer Ther; 17(1); 264–75. ©2017 AACR.
from Cancer via ola Kala on Inoreader http://ift.tt/2lBK1JZ
via IFTTT
Therapeutic Impact of Nanoparticle Therapy Targeting Tumor-Associated Macrophages
Antiangiogenic therapies, despite initial encouragement, have demonstrated a limited benefit in ovarian cancer. Laboratory studies suggest antiangiogenic therapy–induced hypoxia can induce tumor "stemness" as resistance to antiangiogenic therapy develops and limits the therapeutic benefit. Resistance to antiangiogenic therapy and an induction of tumor stemness may be mediated by proangiogenic tumor-associated macrophages (TAM). As such, TAMs have been proposed as a therapeutic target. We demonstrate here that ovarian TAMs express high levels of the folate receptor-2 (FOLR2) and can be selectively targeted using G5-dendrimer nanoparticles using methotrexate as both a ligand and a toxin. G5-methotrexate (G5-MTX) nanoparticles deplete TAMs in both solid tumor and ascites models of ovarian cancer. As a therapeutic agent, these nanoparticles are more effective than cisplatin. Importantly, these nanoparticles could (i) overcome resistance to antiangiogenic therapy, (ii) prevent antiangiogenic therapy–induced increases in cancer stem–like cells in both murine and human tumor cell models, (iii) prevent antiangiogenic therapy–induced increases in VEGF-C, and (iv) prevent antiangiogenic therapy–induced BRCA1 gene expression. Combined, this work strongly supports the development of TAM-targeted nanoparticle therapy. Mol Cancer Ther; 17(1); 96–106. ©2017 AACR.
from Cancer via ola Kala on Inoreader http://ift.tt/2qb0nOK
via IFTTT
Overcoming Resistance to Cetuximab with Honokiol, A Small-Molecule Polyphenol
Overexpression and activation of the EGFR have been linked to poor prognosis in several human cancers. Cetuximab is a mAb against EGFR that is used for the treatment in head and neck squamous cell carcinoma (HNSCC) and metastatic colorectal cancer. Unfortunately, most tumors have intrinsic or will acquire resistance to cetuximab during the course of therapy. Honokiol is a natural compound found in the bark and leaves of the Chinese Magnolia tree and is established to have several anticancer properties without appreciable toxicity. In this study, we hypothesized that combining cetuximab and honokiol treatments could overcome acquired resistance to cetuximab. We previously developed a model of acquired resistance to cetuximab in non–small cell lung cancer H226 cell line. Treatment of cetuximab-resistant clones with honokiol and cetuximab resulted in a robust antiproliferative response. Immunoblot analysis revealed the HER family and their signaling pathways were downregulated after combination treatment, most notably the proliferation (MAPK) and survival (AKT) pathways. In addition, we found a decrease in phosphorylation of DRP1 and reactive oxygen species after combination treatment in cetuximab-resistant clones, which may signify a change in mitochondrial function. Furthermore, we utilized cetuximab-resistant HNSCC patient-derived xenografts (PDX) to test the benefit of combinatorial treatment in vivo. There was significant growth delay in PDX tumors after combination treatment with a subsequent downregulation of active MAPK, AKT, and DRP1 signaling as seen in vitro. Collectively, these data suggest that honokiol is a promising natural compound in overcoming acquired resistance to cetuximab. Mol Cancer Ther; 17(1); 204–14. ©2017 AACR.
from Cancer via ola Kala on Inoreader http://ift.tt/2lzKmgv
via IFTTT
Comparative Oncology Evaluation of Intravenous Recombinant Oncolytic Vesicular Stomatitis Virus Therapy in Spontaneous Canine Cancer
Clinical translation of intravenous therapies to treat disseminated or metastatic cancer is imperative. Comparative oncology, the evaluation of novel cancer therapies in animals with spontaneous cancer, can be utilized to inform and accelerate clinical translation. Preclinical murine studies demonstrate that single-shot systemic therapy with a vesicular stomatitis virus (VSV)-IFNβ-NIS, a novel recombinant oncolytic VSV, can induce curative remission in tumor-bearing mice. Clinical translation of VSV-IFNβ-NIS therapy is dependent on comprehensive assessment of clinical toxicities, virus shedding, pharmacokinetics, and efficacy in clinically relevant models. Dogs spontaneously develop cancer with comparable etiology, clinical progression, and response to therapy as human malignancies. A comparative oncology study was carried out to investigate feasibility and tolerability of intravenous oncolytic VSV-IFNβ-NIS therapy in pet dogs with spontaneous cancer. Nine dogs with various malignancies were treated with a single intravenous dose of VSV-IFNβ-NIS. Two dogs with high-grade peripheral T-cell lymphoma had rapid but transient remission of disseminated disease and transient hepatotoxicity that resolved spontaneously. There was no shedding of infectious virus. Correlative pharmacokinetic studies revealed elevated levels of VSV RNA in blood in dogs with measurable disease remission. This is the first evaluation of intravenous oncolytic virus therapy for spontaneous canine cancer, demonstrating that VSV-IFNβ-NIS is well-tolerated and safe in dogs with advanced or metastatic disease. This approach has informed clinical translation, including dose and target indication selection, leading to a clinical investigation of intravenous VSV-IFNβ-NIS therapy, and provided preliminary evidence of clinical efficacy and potential biomarkers that correlate with therapeutic response. Mol Cancer Ther; 17(1); 316–26. ©2017 AACR.
http://ift.tt/2lBILGT
Evaluation of CDK12 Protein Expression as a Potential Novel Biomarker for DNA Damage Response-Targeted Therapies in Breast Cancer
Disruption of Cyclin-Dependent Kinase 12 (CDK12) is known to lead to defects in DNA repair and sensitivity to platinum salts and PARP1/2 inhibitors. However, CDK12 has also been proposed as an oncogene in breast cancer. We therefore aimed to assess the frequency and distribution of CDK12 protein expression by IHC in independent cohorts of breast cancer and correlate this with outcome and genomic status. We found that 21% of primary unselected breast cancers were CDK12 high, and 10.5% were absent, by IHC. CDK12 positivity correlated with HER2 positivity but was not an independent predictor of breast cancer–specific survival taking HER2 status into account; however, absent CDK12 protein expression significantly correlated with a triple-negative phenotype. Interestingly, CDK12 protein absence was associated with reduced expression of a number of DDR proteins including ATR, Ku70/Ku80, PARP1, DNA-PK, and H2AX, suggesting a novel mechanism of CDK12-associated DDR dysregulation in breast cancer. Our data suggest that diagnostic IHC quantification of CDK12 in breast cancer is feasible, with CDK12 absence possibly signifying defective DDR function. This may have important therapeutic implications, particularly for triple-negative breast cancers. Mol Cancer Ther; 17(1); 306–15. ©2017 AACR.
http://ift.tt/2qcIJdf
Targeted Delivery of STAT-3 Modulator to Breast Cancer Stem-Like Cells Downregulates a Series of Stemness Genes
Cancer stem cells are known to be controlled by pathways that are dormant in normal adult cells, for example, PTEN, which is a negative regulator of transcription factor STAT3. STAT3 regulates genes that are involved in stem cell self-renewal and thus represents a novel therapeutic target of enormous clinical significance. Studies on breast cancer stem cells (BCSC) have been also significantly correlated with STATs. We describe here for the first time a novel strategy to selectively target CSCs and to induce downregulation of STAT3 downstream target genes reducing expression of series of "stem-ness genes" in treated tumors. In vitro and in vivo experiments were performed to evaluate functional activity with gene and protein expression studies. The results of the study indicate that this targeted delivery approach deactivates STAT3 causing a reduction of CD44+/CD24– CSC populations with aptly tracked gene and protein regulations of "stemness" characteristics. Mol Cancer Ther; 17(1); 119–29. ©2017 AACR.
from Cancer via ola Kala on Inoreader http://ift.tt/2qajgkT
via IFTTT
ALK Inhibitor Response in Melanomas Expressing EML4-ALK Fusions and Alternate ALK Isoforms
Oncogenic ALK fusions occur in several types of cancer and can be effectively treated with ALK inhibitors; however, ALK fusions and treatment response have not been characterized in malignant melanomas. Recently, a novel isoform of ALK (ALKATI) was reported in 11% of melanomas but the response of melanomas expressing ALKATI to ALK inhibition has not been well characterized. We analyzed 45 melanoma patient-derived xenograft models for ALK mRNA and protein expression. ALK expression was identified in 11 of 45 (24.4%) melanomas. Ten melanomas express wild-type (wt) ALK and/or ALKATI and one mucosal melanoma expresses multiple novel EML4-ALK fusion variants. Melanoma cells expressing different ALK variants were tested for response to ALK inhibitors. Whereas the melanoma expressing EML4-ALK were sensitive to ALK inhibitors in vitro and in vivo, the melanomas expressing wt ALK or ALKATI were not sensitive to ALK inhibitors. In addition, a patient with mucosal melanoma expressing ALKATI was treated with an ALK/ROS1/TRK inhibitor (entrectinib) on a phase I trial but did not respond. Our results demonstrate ALK fusions occur in malignant melanomas and respond to targeted therapy, whereas melanomas expressing ALKATI do not respond to ALK inhibitors. Targeting ALK fusions is an effective therapeutic option for a subset of melanoma patients, but additional clinical studies are needed to determine the efficacy of targeted therapies in melanomas expressing wt ALK or ALKATI. Mol Cancer Ther; 17(1); 222–31. ©2017 AACR.
from Cancer via ola Kala on Inoreader http://ift.tt/2lBHksb
via IFTTT
"Wnt/{beta}-Catenin in GIST"--Letter
In an article published on September, 2017, in Molecular Cancer Therapeutics, Zeng and colleagues showed that the WNT/β-catenin oncogenic pathway was activated in a subset of human gastrointestinal stromal tumors (GIST) and that inhibiting its signaling alone or in combination with imatinib has antitumor efficacy in vitro and in vivo in imatinib-sensitive and resistant preclinical models. However, they concluded that "more investigation is needed to correlate β-catenin activation with clinicopathologic features in GIST clinical samples." Here, we examined the activation score of the β-catenin pathway in 160 clinically annotated clinical samples of operated primary GISTs. We showed that the β-catenin activation score, assessed as continuous variable, was heterogeneous across samples. Higher score was associated with certain prognostic clinicopathologic characteristics, including mutational status, tumor size, and AFIP classification, and even more importantly, with more postoperative relapses in uni- and multivariate analyses. Such unfavorable independent prognostic value of β-catenin activation reinforces the potential therapeutic value of this new target in GIST and nicely complements Zeng's study. Mol Cancer Ther; 17(1); 327–8. ©2018 AACR.
http://ift.tt/2lCnn4x
miR-20a Regulates FAS Expression in Osteosarcoma Cells by Modulating FAS Promoter Activity and Can be Therapeutically Targeted to Inhibit Lung Metastases
The metastatic potential of osteosarcoma cells is inversely correlated to cell surface FAS expression. Downregulation of FAS allows osteosarcoma cells to escape FAS ligand–mediated apoptosis when they enter a FAS ligand–positive microenvironment such as the lung. We have previously demonstrated that miR-20a, encoded by the miR-17-92 cluster, downregulates FAS expression in osteosarcoma. We further demonstrated an inverse correlation between FAS expression and miR-20a expression. However, the mechanism of FAS regulation by miR-20a was still unclear. The purpose of the current study was to evaluate the mechanism of FAS regulation by miR-20a in vitro and test the effect of targeting miR-20a in vivo. We investigated whether miR-20a's downregulation of FAS was mediated by binding to the 3'-untranslated region (3'-UTR) of FAS mRNA with the consequent induction of mRNA degradation or translational suppression. We identified and mutated two miR-20a binding sites on the FAS mRNA 3'-UTR. Using luciferase reporter assays, we demonstrated that miR-20a did not bind to either the wild-type or mutated FAS 3'-UTR. In contrast, overexpression of miR-20a resulted in downregulation of FAS promoter activity. Similarly, the inhibition of miR-20a increased FAS promoter activity. The critical region identified on the FAS promoter was between –240 bp and –150 bp. Delivery of anti-miR-20a in vivo using nanoparticles in mice with established osteosarcoma lung metastases resulted in upregulation of FAS and tumor growth inhibition. Taken together, our data suggest that miR-20a regulates FAS expression through the modulation of the FAS promoter and that targeting miR-20a using anti-miR-20a has therapeutic potential. Mol Cancer Ther; 17(1); 130–9. ©2017 AACR.
from Cancer via ola Kala on Inoreader http://ift.tt/2lBjOv4
via IFTTT
Clinical Application of Circulating Tumor DNA in the Genetic Analysis of Patients with Advanced GIST
Gastrointestinal stromal tumors (GIST) are the most common mesenchymal tumor of digestive tract. In the past, tissue biopsy was the main method for the diagnosis of GISTs. Although, circulating tumor DNA (ctDNA) detection by next-generation sequencing (NGS) may be a feasible and replaceable method for diagnosis of GISTs. We retrospectively analyzed the data for ctDNA and tissue DNA detection from 32 advanced GIST patients. We found that NGS obviously increased the positive rate of ctDNA detection. ctDNA detection identified rare mutations that were not detected in tissue DNA detection. Tumor size and Ki-67 were significant influencing factors of the positive rate of ctDNA detection and concordance between ctDNA and tissue DNA detection. In all patients, the concordance rate between ctDNA and tissue DNA detection was 71.9%, with moderate concordance, but the concordance was strong for patients with tumor size > 10 cm or Ki-67 > 5%. Tumor size, mitotic figure, Ki-67, and ctDNA mutation type were the significant influencing factors of prognosis, but only tumor size and ctDNA mutation type, were the independent prognostic factors for advanced GIST patients. We confirmed that ctDNA detection by NGS is a feasible and promising method for the diagnosis and prognosis of advanced GIST patients. Mol Cancer Ther; 17(1); 290–6. ©2017 AACR.
http://ift.tt/2q92ySN
HIF2{alpha}-Targeted RNAi Therapeutic Inhibits Clear Cell Renal Cell Carcinoma
Targeted therapy against VEGF and mTOR pathways has been established as the standard-of-care for metastatic clear cell renal cell carcinoma (ccRCC); however, these treatments frequently fail and most patients become refractory requiring subsequent alternative therapeutic options. Therefore, development of innovative and effective treatments is imperative. About 80%–90% of ccRCC tumors express an inactive mutant form of the von Hippel-Lindau protein (pVHL), an E3 ubiquitin ligase that promotes target protein degradation. Strong genetic and experimental evidence supports the correlate that pVHL functional loss leads to the accumulation of the transcription factor hypoxia-inducible factor 2α (HIF2α) and that an overabundance of HIF2α functions as a tumorigenic driver of ccRCC. In this report, we describe an RNAi therapeutic for HIF2α that utilizes a targeting ligand that selectively binds to integrins αvβ3 and αvβ5 frequently overexpressed in ccRCC. We demonstrate that functional delivery of a HIF2α-specific RNAi trigger resulted in HIF2α gene silencing and subsequent tumor growth inhibition and degeneration in an established orthotopic ccRCC xenograft model. Mol Cancer Ther; 17(1); 140–9. ©2017 AACR.
from Cancer via ola Kala on Inoreader http://ift.tt/2lBjxIy
via IFTTT
CCL26 Participates in the PRL-3-Induced Promotion of Colorectal Cancer Invasion by Stimulating Tumor-Associated Macrophage Infiltration
Both phosphatase of regenerating liver-3 (PRL-3) and tumor-associated macrophages (TAM) influence cancer progression. Whether PRL-3 plays a critical role in colorectal cancer invasion and metastasis by inducing TAM infiltration remains unclear. In the current study, we investigated the effects of chemokine ligand 26 (CCL26) on TAM infiltration and colorectal cancer invasion and the underlying mechanism in colorectal cancer cells by overexpressing or silencing PRL-3. We found that PRL-3 upregulated CCL26 expression correlatively and participated in cell migration, according to the results of gene ontology analysis. In addition, IHC analysis results indicated that the PRL-3 and CCL26 levels were positively correlated and elevated in stage III and IV colorectal cancer tissues and were associated with a worse prognosis in colorectal cancer patients. Furthermore, we demonstrated that CCL26 induced TAM infiltration by CCL26 binding to the CCR3 receptor. When LoVo-P and HT29-C cells were cocultured with TAMs, CCL26 binding to the CCR3 receptor enhanced the invasiveness of LoVo-P and HT29-C cells by mobilizing intracellular Ca2+of TAMs to increase the expression of IL6 and IL8. In addition, IHC results indicated that protein levels of CCR3 and TAMs counts were higher in stage III and IV colorectal cancer tissues and correlated with CCL26. Moreover, similar results were observed in vivo using mice injected with LoVo-P and HT29-C cells. These data indicate that PRL-3 may represent a potential prognostic marker that promotes colorectal cancer invasion and metastasis by upregulating CCL26 to induce TAM infiltration. Mol Cancer Ther; 17(1); 276–89. ©2017 AACR.
http://ift.tt/2lBKifZ
Ceritinib Enhances the Efficacy of Trametinib in BRAF/NRAS-Wild-Type Melanoma Cell Lines
Targeted therapy options are currently lacking for the heterogeneous population of patients whose melanomas lack BRAF or NRAS mutations (~35% of cases). We undertook a chemical biology screen to identify potential novel drug targets for this understudied group of tumors. Screening a panel of 8 BRAF/NRAS-WT melanoma cell lines against 240 targeted drugs identified ceritinib and trametinib as potential hits with single-agent activity. Ceritinib enhanced the efficacy of trametinib across the majority of the BRAF/NRAS-WT cell lines, and the combination showed increased cytotoxicity in both three-dimensional spheroid culture and long-term colony formation experiments. Coadministration of ceritinib and trametinib led to robust inhibition of tumor growth in an in vivo xenograft BRAF/NRAS-WT melanoma model; this was not due to ALK inhibition by ceritinib. Mechanistic studies showed the ceritinib–trametinib combination to increase suppression of MAPK and TORC1 signaling. Similar results were seen when BRAF/NRAS-WT melanoma cells were treated with a combination of trametinib and the TORC1/2 inhibitor INK128. We next used mass spectrometry–based chemical proteomics and identified known and new ceritinib targets, such as IGF1R and ACK1, respectively. Validation studies suggested that ceritinib could suppress mTORC1 signaling in the presence of trametinib through inhibition of IGF1R and/or ACK1 in a cell line–dependent manner. Together, our studies demonstrated that combining a specific inhibitor (trametinib) with a more broadly targeted agent (ceritinib) has efficacy against tumors with heterogeneous mutational profiles. Mol Cancer Ther; 17(1); 73–83. ©2017 AACR.
from Cancer via ola Kala on Inoreader http://ift.tt/2lB58MN
via IFTTT
The Mutational Landscape of Gastrointestinal Malignancies as Reflected by Circulating Tumor DNA
We aimed to assess the utility of a novel, noninvasive method of detecting genomic alterations in patients with gastrointestinal malignancies, i.e., the use of liquid biopsies to obtain blood-derived circulating tumor DNA (ctDNA) through an analysis of the genomic landscape of ctDNA (68 genes) from 213 patients with advanced gastrointestinal cancers. The most common cancer types were colorectal adenocarcinoma (N = 55; 26%), appendiceal adenocarcinoma (N = 46; 22%), hepatocellular carcinoma (N = 31; 15%), and pancreatic ductal adenocarcinoma (N = 25; 12%). The majority of patients (58%) had ≥1 characterized alteration (excluded variants of unknown significance). The median number of characterized alterations was 1 (range, 0–13). The number of detected alterations per patient varied between different cancer types: in hepatocellular carcinoma, 74% of patients (23/31) had ≥1 characterized alteration(s) versus 24% of appendiceal adenocarcinoma patients (11/46). The median percent ctDNA among characterized alterations was 2.50% (interquartile range, 0.76%–8.96%). Overall, 95% of patients (117/123) had distinct molecular portfolios with 143 unique characterized alterations within 56 genes. Overall, concordance rates of 96%, 94%, 95%, and 91%, respectively, were found between ctDNA and tissue biopsy (N = 105 patients) in the four most common alterations (KRAS amplification, MYC amplification, KRAS G12V, and EGFR amplification). Of 123 patients with characterized alterations, >99% (122/123; 57% of entire population tested; 122/213) had one or more alterations potentially actionable by experimental or approved drugs. These observations suggest that many patients with gastrointestinal tumors, including difficult-to-biopsy malignancies like hepatocellular cancers, frequently have discernible and theoretically pharmacologically tractable ctDNA alterations that merit further studies in prospective trials. Mol Cancer Ther; 17(1); 297–305. ©2017 AACR.
http://ift.tt/2qgWxDR
AKT1low Quiescent Cancer Cells Promote Solid Tumor Growth
Human tumor growth depends on rapidly dividing cancer cells driving population expansion. Even advanced tumors, however, contain slowly proliferating cancer cells for reasons that remain unclear. Here, we selectively disrupt the ability of rapidly proliferating cancer cells to spawn AKT1low daughter cells that are rare, slowly proliferating, tumor-initiating, and chemotherapy-resistant, using β1-integrin activation and the AKT1-E17K–mutant oncoprotein as experimental tools in vivo. Surprisingly, we find that selective depletion of AKT1low slow proliferators actually reduces the growth of a molecularly diverse panel of human cancer cell xenograft models without globally altering cell proliferation or survival in vivo. Moreover, we find that unusual cancer patients with AKT1-E17K–mutant solid tumors also fail to produce AKT1low quiescent cancer cells and that this correlates with significantly prolonged survival after adjuvant treatment compared with other patients. These findings support a model whereby human solid tumor growth depends on not only rapidly proliferating cancer cells but also on the continuous production of AKT1low slow proliferators. Mol Cancer Ther; 17(1); 254–63. ©2017 AACR.
http://ift.tt/2lBKbB5
Caveolae-Mediated Endocytosis as a Novel Mechanism of Resistance to Trastuzumab Emtansine (T-DM1)
Trastuzumab emtansine (T-DM1) is an antibody–drug conjugate (ADC) that has demonstrated clinical benefit for patients with HER2+ metastatic breast cancer; however, its clinical activity is limited by inherent or acquired drug resistance. The molecular mechanisms that drive clinical resistance to T-DM1, especially in HER2+ tumors, are not well understood. We used HER2+ cell lines to develop models of T-DM1 resistance using a cyclical dosing schema in which cells received T-DM1 in an "on-off" routine until a T-DM1–resistant population was generated. T-DM1–resistant N87 cells (N87-TM) were cross-resistant to a panel of trastuzumab-ADCs (T-ADCs) with non–cleavable-linked auristatins. N87-TM cells do not have a decrease in HER2 protein levels or an increase in drug transporter protein (e.g., MDR1) expression compared with parental N87 cells. Intriguingly, T-ADCs using auristatin payloads attached via an enzymatically cleavable linker overcome T-DM1 resistance in N87-TM cells. Importantly, N87-TM cells implanted into athymic mice formed T-DM1 refractory tumors that remain sensitive to T-ADCs with cleavable-linked auristatin payloads. Comparative proteomic profiling suggested enrichment in proteins that mediate caveolae formation and endocytosis in the N87-TM cells. Indeed, N87-TM cells internalize T-ADCs into intracellular caveolin-1 (CAV1)–positive puncta and alter their trafficking to the lysosome compared with N87 cells. T-DM1 colocalization into intracellular CAV1-positive puncta correlated with reduced response to T-DM1 in a panel of HER2+ cell lines. Together, these data suggest that caveolae-mediated endocytosis of T-DM1 may serve as a novel predictive biomarker for patient response to T-DM1. Mol Cancer Ther; 17(1); 243–53. ©2017 AACR.
http://ift.tt/2qb4jyJ
Metabolite Profiling Reveals the Glutathione Biosynthetic Pathway as a Therapeutic Target in Triple-Negative Breast Cancer
Cancer cells can exhibit altered dependency on specific metabolic pathways and targeting these dependencies is a promising therapeutic strategy. Triple-negative breast cancer (TNBC) is an aggressive and genomically heterogeneous subset of breast cancer that is resistant to existing targeted therapies. To identify metabolic pathway dependencies in TNBC, we first conducted mass spectrometry–based metabolomics of TNBC and control cells. Relative levels of intracellular metabolites distinguished TNBC from nontransformed breast epithelia and revealed two metabolic subtypes within TNBC that correlate with markers of basal-like versus non-basal–like status. Among the distinguishing metabolites, levels of the cellular redox buffer glutathione were lower in TNBC cell lines compared to controls and markedly lower in non-basal–like TNBC. Significantly, these cell lines showed enhanced sensitivity to pharmacologic inhibition of glutathione biosynthesis that was rescued by N-acetylcysteine, demonstrating a dependence on glutathione production to suppress ROS and support tumor cell survival. Consistent with this, patients whose tumors express elevated levels of -glutamylcysteine ligase, the rate-limiting enzyme in glutathione biosynthesis, had significantly poorer survival. We find, further, that agents that limit the availability of glutathione precursors enhance both glutathione depletion and TNBC cell killing by -glutamylcysteine ligase inhibitors in vitro. Importantly, we demonstrate the ability to this approach to suppress glutathione levels and TNBC xenograft growth in vivo. Overall, these findings support the potential of targeting the glutathione biosynthetic pathway as a therapeutic strategy in TNBC and identify the non-basal-like subset as most likely to respond. Mol Cancer Ther; 17(1); 264–75. ©2017 AACR.
http://ift.tt/2lBK1JZ
Therapeutic Impact of Nanoparticle Therapy Targeting Tumor-Associated Macrophages
Antiangiogenic therapies, despite initial encouragement, have demonstrated a limited benefit in ovarian cancer. Laboratory studies suggest antiangiogenic therapy–induced hypoxia can induce tumor "stemness" as resistance to antiangiogenic therapy develops and limits the therapeutic benefit. Resistance to antiangiogenic therapy and an induction of tumor stemness may be mediated by proangiogenic tumor-associated macrophages (TAM). As such, TAMs have been proposed as a therapeutic target. We demonstrate here that ovarian TAMs express high levels of the folate receptor-2 (FOLR2) and can be selectively targeted using G5-dendrimer nanoparticles using methotrexate as both a ligand and a toxin. G5-methotrexate (G5-MTX) nanoparticles deplete TAMs in both solid tumor and ascites models of ovarian cancer. As a therapeutic agent, these nanoparticles are more effective than cisplatin. Importantly, these nanoparticles could (i) overcome resistance to antiangiogenic therapy, (ii) prevent antiangiogenic therapy–induced increases in cancer stem–like cells in both murine and human tumor cell models, (iii) prevent antiangiogenic therapy–induced increases in VEGF-C, and (iv) prevent antiangiogenic therapy–induced BRCA1 gene expression. Combined, this work strongly supports the development of TAM-targeted nanoparticle therapy. Mol Cancer Ther; 17(1); 96–106. ©2017 AACR.
http://ift.tt/2qb0nOK
Overcoming Resistance to Cetuximab with Honokiol, A Small-Molecule Polyphenol
Overexpression and activation of the EGFR have been linked to poor prognosis in several human cancers. Cetuximab is a mAb against EGFR that is used for the treatment in head and neck squamous cell carcinoma (HNSCC) and metastatic colorectal cancer. Unfortunately, most tumors have intrinsic or will acquire resistance to cetuximab during the course of therapy. Honokiol is a natural compound found in the bark and leaves of the Chinese Magnolia tree and is established to have several anticancer properties without appreciable toxicity. In this study, we hypothesized that combining cetuximab and honokiol treatments could overcome acquired resistance to cetuximab. We previously developed a model of acquired resistance to cetuximab in non–small cell lung cancer H226 cell line. Treatment of cetuximab-resistant clones with honokiol and cetuximab resulted in a robust antiproliferative response. Immunoblot analysis revealed the HER family and their signaling pathways were downregulated after combination treatment, most notably the proliferation (MAPK) and survival (AKT) pathways. In addition, we found a decrease in phosphorylation of DRP1 and reactive oxygen species after combination treatment in cetuximab-resistant clones, which may signify a change in mitochondrial function. Furthermore, we utilized cetuximab-resistant HNSCC patient-derived xenografts (PDX) to test the benefit of combinatorial treatment in vivo. There was significant growth delay in PDX tumors after combination treatment with a subsequent downregulation of active MAPK, AKT, and DRP1 signaling as seen in vitro. Collectively, these data suggest that honokiol is a promising natural compound in overcoming acquired resistance to cetuximab. Mol Cancer Ther; 17(1); 204–14. ©2017 AACR.
http://ift.tt/2lzKmgv
JQ1 Induces DNA Damage and Apoptosis, and Inhibits Tumor Growth in a Patient-Derived Xenograft Model of Cholangiocarcinoma
Cholangiocarcinoma (CCA) is a fatal disease with a 5-year survival of <30%. For a majority of patients, chemotherapy is the only therapeutic option, and virtually all patients relapse. Gemcitabine is the first-line agent for treatment of CCA. Patients treated with gemcitabine monotherapy survive ~8 months. Combining this agent with cisplatin increases survival by ~3 months, but neither regimen produces durable remissions. The molecular etiology of this disease is poorly understood. To facilitate molecular characterization and development of effective therapies for CCA, we established a panel of patient-derived xenograft (PDX) models of CCA. We used two of these models to investigate the antitumor efficacy and mechanism of action of the bromodomain inhibitor JQ1, an agent that has not been evaluated for the treatment of CCA. The data show that JQ1 suppressed the growth of the CCA PDX model CCA2 and demonstrate that growth suppression was concomitant with inhibition of c-Myc protein expression. A second model (CCA1) was JQ1-insensitive, with tumor progression and c-Myc expression unaffected by exposure to this agent. Also selective to CCA2 tumors, JQ1 induced DNA damage and apoptosis and downregulated multiple c-Myc transcriptional targets that regulate cell-cycle progression and DNA repair. These findings suggest that c-Myc inhibition and several of its transcriptional targets may contribute to the mechanism of action of JQ1 in this tumor type. We conclude that BET inhibitors such as JQ1 warrant further investigation for the treatment of CCA. Mol Cancer Ther; 17(1); 107–18. ©2017 AACR.
http://ift.tt/2qajkB9
A Novel Therapeutic Strategy for Pancreatic Cancer: Targeting Cell Surface Glycan Using rBC2LC-N Lectin-Drug Conjugate (LDC)
Various cancers, including pancreatic ductal adenocarcinoma (PDAC), remain intractable even with costly tumor-targeting antibody drugs. Because the outermost coatings of cancer cells are composed of cell-specific glycan layers (glycocalyx), lectins, proteins with glycan-binding potential, were evaluated for possible use as drug carriers in PDAC treatment. A human PDAC cell line with well-to-moderately differentiated properties (Capan-1) was subjected to lectin microarray analysis to identify specific lectin–glycan pairs. The selected lectin was fused with a bacterial exotoxin for the construction of a lectin–drug conjugate (LDC), and its safety and antitumor effects were evaluated. A specific affinity between a recombinant bacterial C-type lectin (rBC2LC-N) and Capan-1 was identified, and its positivity was confirmed in 69 human samples. In contrast to the belief that all lectins mediate harmful hemagglutination, rBC2LC-N did not cause hemagglutination with human erythrocytes and was safely administered to mice. The 50% inhibitory concentration of LDC to Capan-1 (1.04 pg/mL = 0.0195 pmol/L) was 1/1,000 lower than that reported for conventional immunotoxins. The intraperitoneal administration of LDC reduced the tumor weight from 390 to 130.8 mg (P < 0.01) in an orthotopic model and reduced the number of nodules from 48 to 3 (P < 0.001) and improved survival from 62 to 105 days in a peritoneal dissemination model (P < 0.0001). In addition, the effect of LDC was reproduced in nodules from patient-derived PDAC xenografts through intravenous injection. Herein, we show the concept of utilizing lectins as drug carriers to target glycans on the cancer cell surface, highlighting new insights into cancer treatments. Mol Cancer Ther; 17(1); 183–95. ©2017 AACR.
http://ift.tt/2lD1rGl
Targeted Delivery of STAT-3 Modulator to Breast Cancer Stem-Like Cells Downregulates a Series of Stemness Genes
Cancer stem cells are known to be controlled by pathways that are dormant in normal adult cells, for example, PTEN, which is a negative regulator of transcription factor STAT3. STAT3 regulates genes that are involved in stem cell self-renewal and thus represents a novel therapeutic target of enormous clinical significance. Studies on breast cancer stem cells (BCSC) have been also significantly correlated with STATs. We describe here for the first time a novel strategy to selectively target CSCs and to induce downregulation of STAT3 downstream target genes reducing expression of series of "stem-ness genes" in treated tumors. In vitro and in vivo experiments were performed to evaluate functional activity with gene and protein expression studies. The results of the study indicate that this targeted delivery approach deactivates STAT3 causing a reduction of CD44+/CD24– CSC populations with aptly tracked gene and protein regulations of "stemness" characteristics. Mol Cancer Ther; 17(1); 119–29. ©2017 AACR.
http://ift.tt/2qajgkT
ALK Inhibitor Response in Melanomas Expressing EML4-ALK Fusions and Alternate ALK Isoforms
Oncogenic ALK fusions occur in several types of cancer and can be effectively treated with ALK inhibitors; however, ALK fusions and treatment response have not been characterized in malignant melanomas. Recently, a novel isoform of ALK (ALKATI) was reported in 11% of melanomas but the response of melanomas expressing ALKATI to ALK inhibition has not been well characterized. We analyzed 45 melanoma patient-derived xenograft models for ALK mRNA and protein expression. ALK expression was identified in 11 of 45 (24.4%) melanomas. Ten melanomas express wild-type (wt) ALK and/or ALKATI and one mucosal melanoma expresses multiple novel EML4-ALK fusion variants. Melanoma cells expressing different ALK variants were tested for response to ALK inhibitors. Whereas the melanoma expressing EML4-ALK were sensitive to ALK inhibitors in vitro and in vivo, the melanomas expressing wt ALK or ALKATI were not sensitive to ALK inhibitors. In addition, a patient with mucosal melanoma expressing ALKATI was treated with an ALK/ROS1/TRK inhibitor (entrectinib) on a phase I trial but did not respond. Our results demonstrate ALK fusions occur in malignant melanomas and respond to targeted therapy, whereas melanomas expressing ALKATI do not respond to ALK inhibitors. Targeting ALK fusions is an effective therapeutic option for a subset of melanoma patients, but additional clinical studies are needed to determine the efficacy of targeted therapies in melanomas expressing wt ALK or ALKATI. Mol Cancer Ther; 17(1); 222–31. ©2017 AACR.
http://ift.tt/2lBHksb
miR-20a Regulates FAS Expression in Osteosarcoma Cells by Modulating FAS Promoter Activity and Can be Therapeutically Targeted to Inhibit Lung Metastases
The metastatic potential of osteosarcoma cells is inversely correlated to cell surface FAS expression. Downregulation of FAS allows osteosarcoma cells to escape FAS ligand–mediated apoptosis when they enter a FAS ligand–positive microenvironment such as the lung. We have previously demonstrated that miR-20a, encoded by the miR-17-92 cluster, downregulates FAS expression in osteosarcoma. We further demonstrated an inverse correlation between FAS expression and miR-20a expression. However, the mechanism of FAS regulation by miR-20a was still unclear. The purpose of the current study was to evaluate the mechanism of FAS regulation by miR-20a in vitro and test the effect of targeting miR-20a in vivo. We investigated whether miR-20a's downregulation of FAS was mediated by binding to the 3'-untranslated region (3'-UTR) of FAS mRNA with the consequent induction of mRNA degradation or translational suppression. We identified and mutated two miR-20a binding sites on the FAS mRNA 3'-UTR. Using luciferase reporter assays, we demonstrated that miR-20a did not bind to either the wild-type or mutated FAS 3'-UTR. In contrast, overexpression of miR-20a resulted in downregulation of FAS promoter activity. Similarly, the inhibition of miR-20a increased FAS promoter activity. The critical region identified on the FAS promoter was between –240 bp and –150 bp. Delivery of anti-miR-20a in vivo using nanoparticles in mice with established osteosarcoma lung metastases resulted in upregulation of FAS and tumor growth inhibition. Taken together, our data suggest that miR-20a regulates FAS expression through the modulation of the FAS promoter and that targeting miR-20a using anti-miR-20a has therapeutic potential. Mol Cancer Ther; 17(1); 130–9. ©2017 AACR.
http://ift.tt/2lBjOv4
Targeting Phosphatidylserine with Calcium-Dependent Protein-Drug Conjugates for the Treatment of Cancer
In response to cellular stress, phosphatidylserine is exposed on the outer membrane leaflet of tumor blood vessels and cancer cells, motivating the development of phosphatidylserine-specific therapies. The generation of drug-conjugated phosphatidylserine-targeting agents represents an unexplored therapeutic approach, for which antitumor effects are critically dependent on efficient internalization and lysosomal delivery of the cytotoxic drug. In the current study, we have generated phosphatidylserine-targeting agents by fusing phosphatidylserine-binding domains to a human IgG1-derived Fc fragment. The tumor localization and pharmacokinetics of several phosphatidylserine-specific Fc fusions have been analyzed in mice and demonstrate that Fc-Syt1, a fusion containing the synaptotagmin 1 C2A domain, effectively targets tumor tissue. Conjugation of Fc-Syt1 to the cytotoxic drug monomethyl auristatin E results in a protein–drug conjugate (PDC) that is internalized into target cells and, due to the Ca2+ dependence of phosphatidylserine binding, dissociates from phosphatidylserine in early endosomes. The released PDC is efficiently delivered to lysosomes and has potent antitumor effects in mouse xenograft tumor models. Interestingly, although an engineered, tetravalent Fc-Syt1 fusion shows increased binding to target cells, this higher avidity variant demonstrates reduced persistence and therapeutic effects compared with bivalent Fc-Syt1. Collectively, these studies show that finely tuned, Ca2+-switched phosphatidylserine-targeting agents can be therapeutically efficacious. Mol Cancer Ther; 17(1); 169–82. ©2017 AACR.
http://ift.tt/2qb0mua
HIF2{alpha}-Targeted RNAi Therapeutic Inhibits Clear Cell Renal Cell Carcinoma
Targeted therapy against VEGF and mTOR pathways has been established as the standard-of-care for metastatic clear cell renal cell carcinoma (ccRCC); however, these treatments frequently fail and most patients become refractory requiring subsequent alternative therapeutic options. Therefore, development of innovative and effective treatments is imperative. About 80%–90% of ccRCC tumors express an inactive mutant form of the von Hippel-Lindau protein (pVHL), an E3 ubiquitin ligase that promotes target protein degradation. Strong genetic and experimental evidence supports the correlate that pVHL functional loss leads to the accumulation of the transcription factor hypoxia-inducible factor 2α (HIF2α) and that an overabundance of HIF2α functions as a tumorigenic driver of ccRCC. In this report, we describe an RNAi therapeutic for HIF2α that utilizes a targeting ligand that selectively binds to integrins αvβ3 and αvβ5 frequently overexpressed in ccRCC. We demonstrate that functional delivery of a HIF2α-specific RNAi trigger resulted in HIF2α gene silencing and subsequent tumor growth inhibition and degeneration in an established orthotopic ccRCC xenograft model. Mol Cancer Ther; 17(1); 140–9. ©2017 AACR.
http://ift.tt/2lBjxIy
Selective and Concentrated Accretion of SN-38 with a CEACAM5-Targeting Antibody-Drug Conjugate (ADC), Labetuzumab Govitecan (IMMU-130)
Labetuzumab govitecan (IMMU-130), an antibody–drug conjugate (ADC) with an average of 7.6 SN-38/IgG, was evaluated for its potential to enhance delivery of SN-38 to human colonic tumor xenografts. Mice bearing LS174T or GW-39 human colonic tumor xenografts were injected with irinotecan or IMMU-130 (SN-38 equivalents ~500 or ~16 μg, respectively). Serum and homogenates of tumors, liver, and small intestine were extracted, and SN-38, SN-38G (glucuronidated SN-38), and irinotecan concentrations determined by reversed-phase HPLC. Irinotecan cleared quickly from serum, with only 1% to 2% injected dose/mL after 5 minutes; overall, approximately 20% was converted to SN-38 and SN-38G. At 1 hour with IMMU-130, 45% to 63% injected dose/mL of the SN-38 was in the serum, with >90% bound to the ADC over 3 days, and with low levels of SN-38G. Total SN-38 levels decreased more quickly than the IgG, confirming a gradual SN-38 release from the ADC. AUC analysis found that SN-38 levels were approximately 11- and 16-fold higher in LS174T and GW-39 tumors, respectively, in IMMU-130–treated animals. This delivery advantage is amplified >30-fold when normalized to SN-38 equivalents injected for each product. Levels of SN-38 and SN-38G were appreciably lower in the liver and small intestinal contents in animals given IMMU-130. On the basis of the SN-38 equivalents administered, IMMU-130 potentially delivers >300-fold more SN-38 to CEA-producing tumors compared with irinotecan, while also reducing levels of SN-38 and SN-38G in normal tissues. These observations are consistent with preclinical and clinical data showing efficacy and improved safety. Mol Cancer Ther; 17(1); 196–203. ©2017 AACR.
http://ift.tt/2qeTfR8
Ceritinib Enhances the Efficacy of Trametinib in BRAF/NRAS-Wild-Type Melanoma Cell Lines
Targeted therapy options are currently lacking for the heterogeneous population of patients whose melanomas lack BRAF or NRAS mutations (~35% of cases). We undertook a chemical biology screen to identify potential novel drug targets for this understudied group of tumors. Screening a panel of 8 BRAF/NRAS-WT melanoma cell lines against 240 targeted drugs identified ceritinib and trametinib as potential hits with single-agent activity. Ceritinib enhanced the efficacy of trametinib across the majority of the BRAF/NRAS-WT cell lines, and the combination showed increased cytotoxicity in both three-dimensional spheroid culture and long-term colony formation experiments. Coadministration of ceritinib and trametinib led to robust inhibition of tumor growth in an in vivo xenograft BRAF/NRAS-WT melanoma model; this was not due to ALK inhibition by ceritinib. Mechanistic studies showed the ceritinib–trametinib combination to increase suppression of MAPK and TORC1 signaling. Similar results were seen when BRAF/NRAS-WT melanoma cells were treated with a combination of trametinib and the TORC1/2 inhibitor INK128. We next used mass spectrometry–based chemical proteomics and identified known and new ceritinib targets, such as IGF1R and ACK1, respectively. Validation studies suggested that ceritinib could suppress mTORC1 signaling in the presence of trametinib through inhibition of IGF1R and/or ACK1 in a cell line–dependent manner. Together, our studies demonstrated that combining a specific inhibitor (trametinib) with a more broadly targeted agent (ceritinib) has efficacy against tumors with heterogeneous mutational profiles. Mol Cancer Ther; 17(1); 73–83. ©2017 AACR.
http://ift.tt/2lB58MN
Crk Tyrosine Phosphorylation Regulates PDGF-BB-inducible Src Activation and Breast Tumorigenicity and Metastasis
The activity of Src family kinases (Src being the prototypical member) is tightly regulated by differential phosphorylation on Tyr416 (positive) and Tyr527 (negative), a duet that reciprocally regulates kinase activity. The latter negative regulation of Src on Tyr527 is mediated by C-terminal Src kinase (CSK) that phosphorylates Tyr527 and maintains Src in a clamped negative regulated state by promoting an intramolecular association. Here it is demonstrated that the SH2- and SH3-domain containing adaptor protein CrkII, by virtue of its phosphorylation on Tyr239, regulates the Csk/Src signaling axis to control Src activation. Once phosphorylated, the motif (PIpYARVIQ) forms a consensus sequence for the SH2 domain of CSK to form a pTyr239-CSK complex. Functionally, when expressed in Crk–/– MEFs or in Crk+/+ HS683 cells, Crk Y239F delayed PDGF-BB–inducible Src Tyr416 phosphorylation. Moreover, expression of Crk Y239F in HS683 cells delayed Src kinase activation and suppressed the cell-invasive and -transforming phenotypes. Finally, through loss-of-function and epistasis experiments using CRISPR-Cas9–engineered 4T1 murine breast cancer cells, Crk Tyr239 is implicated in breast cancer tumor growth and metastasis in orthotopic immunocompetent 4T1 mice model of breast adenocarcinoma. These findings delineate a novel role for Crk Tyr239 phosphorylation in the regulation of Src kinases, as well as a potential molecular explanation for a long-standing question as to how Crk regulates the activation of Src kinases.
Implications: These findings provide new perspectives on the versatility of Crk in cancer by demonstrating how Crk mechanistically drives, through a tyrosine phosphorylation–dependent manner, tumor growth, and metastasis. Mol Cancer Res; 16(1); 173–83. ©2017 AACR.
http://ift.tt/2lEHIVT
PKC{varepsilon} Controls Mitotic Progression by Regulating Centrosome Migration and Mitotic Spindle Assembly
To form a proper mitotic spindle, centrosomes must be duplicated and driven poleward in a timely and controlled fashion. Improper timing of centrosome separation and errors in mitotic spindle assembly may lead to chromosome instability, a hallmark of cancer. Protein kinase C epsilon (PKC) has recently emerged as a regulator of several cell-cycle processes associated with the resolution of mitotic catenation during the metaphase–anaphase transition and in regulating the abscission checkpoint. However, an engagement of PKC in earlier (pre)mitotic events has not been addressed. Here, we now establish that PKC controls prophase-to-metaphase progression by coordinating centrosome migration and mitotic spindle assembly in transformed cells. This control is exerted through cytoplasmic dynein function. Importantly, it is also demonstrated that the PKC dependency of mitotic spindle organization is correlated with the nonfunctionality of the TOPO2A-dependent G2 checkpoint, a characteristic of many transformed cells. Thus, PKC appears to become specifically engaged in a programme of controls that are required to support cell-cycle progression in transformed cells, advocating for PKC as a potential cancer therapeutic target.
Implications: The close relationship between PKC dependency for mitotic spindle organization and the nonfunctionality of the TOPO2A-dependent G2 checkpoint, a hallmark of transformed cells, strongly suggests PKC as a therapeutic target in cancer. Mol Cancer Res; 16(1); 3–15. ©2017 AACR.
http://ift.tt/2CuZWDW
HIF-3{alpha} Promotes Metastatic Phenotypes in Pancreatic Cancer by Transcriptional Regulation of the RhoC-ROCK1 Signaling Pathway
Hypoxia contributes to pancreatic cancer progression and promotes its growth and invasion. Previous research principally focused on hypoxia-inducible factor-1 alpha (HIF-1α) and HIF-2α (HIF1A and EPAS1) as the major hypoxia-associated transcription factors in pancreatic cancer. However, the role of HIF-3α (HIF3A) has not been investigated. Therefore, HIF-1α, HIF-2α, and HIF-3α expression levels were measured under normoxic and hypoxic conditions. In addition, HIF-3α expression was measured in human pancreatic cancer tissue specimens and the impact of altered HIF-3α expression on cell invasion and migration was investigated in vitro and in vivo, as well as the underlying mechanisms. Under hypoxic conditions, HIF-3α expression was stimulated in pancreatic cancer cells to a greater degree than HIF-1α and HIF-2α expression. HIF-3α protein levels were also elevated in pancreatic cancer tissues and correlated with reduced survival and greater local invasion and distant metastasis, whereas knockdown of HIF-3α, under hypoxic conditions, suppressed pancreatic cancer cell invasion and migration. Under normoxia, HIF-3α overexpression promoted pancreatic cancer cell invasion and migration and stimulated F-actin polymerization. In summary, HIF-3α promotes pancreatic cancer cell invasion and metastasis in vivo and promotes pancreatic cancer cell invasion and metastasis by transcriptionally activating the RhoC–ROCK1 signaling pathway.
Implications: HIF3α is overexpressed in pancreatic cancer, and targeting the HIF3α/RhoC–ROCK1 signaling pathway may be a novel therapeutic approach for the treatment of pancreatic cancer invasion and metastasis. Mol Cancer Res; 16(1); 124–34. ©2017 AACR.
http://ift.tt/2lHBuVs
Cell Cycle-Dependent Tumor Engraftment and Migration Are Enabled by Aurora-A
Cell-cycle progression and the acquisition of a migratory phenotype are hallmarks of human carcinoma cells that are perceived as independent processes but may be interconnected by molecular pathways that control microtubule nucleation at centrosomes. Here, cell-cycle progression dramatically impacts the engraftment kinetics of 4T1-luciferase2 breast cancer cells in immunocompetent BALB/c or immunocompromised NOD-SCID gamma (NSG) mice. Multiparameter imaging of wound closure assays was used to track cell-cycle progression, cell migration, and associated phenotypes in epithelial cells or carcinoma cells expressing a fluorescence ubiquitin cell-cycle indicator. Cell migration occurred with an elevated velocity and directionality during the S–G2-phase of the cell cycle, and cells in this phase possess front-polarized centrosomes with augmented microtubule nucleation capacity. Inhibition of Aurora kinase-A (AURKA/Aurora-A) dampens these phenotypes without altering cell-cycle progression. During G2-phase, the level of phosphorylated Aurora-A at centrosomes is reduced in hyaluronan-mediated motility receptor (HMMR)-silenced cells as is the nuclear transport of TPX2, an Aurora-A–activating protein. TPX2 nuclear transport depends upon HMMR-T703, which releases TPX2 from a complex with importin-α (KPNA2) at the nuclear envelope. Finally, the abundance of phosphorylated HMMR-T703, a substrate for Aurora-A, predicts breast cancer–specific survival and relapse-free survival in patients with estrogen receptor (ER)–negative (n = 941), triple-negative (TNBC) phenotype (n = 538), or basal-like subtype (n = 293) breast cancers, but not in those patients with ER-positive breast cancer (n = 2,218). Together, these data demonstrate an Aurora-A/TPX2/HMMR molecular axis that intersects cell-cycle progression and cell migration.
Implications: Tumor cell engraftment, migration, and cell-cycle progression share common regulation of the microtubule cytoskeleton through the Aurora-A/TPX2/HMMR axis, which has the potential to influence the survival of patients with ER-negative breast tumors. Mol Cancer Res; 16(1); 16–31. ©2017 AACR.
http://ift.tt/2Ct7Kpn
A Large-Scale RNAi Screen Identifies SGK1 as a Key Survival Kinase for GBM Stem Cells
Glioblastoma multiforme (GBM) is the most common type of primary malignant brain cancer and has a very poor prognosis. A subpopulation of cells known as GBM stem-like cells (GBM-SC) have the capacity to initiate and sustain tumor growth and possess molecular characteristics similar to the parental tumor. GBM-SCs are known to be enriched in hypoxic niches and may contribute to therapeutic resistance. Therefore, to identify genetic determinants important for the proliferation and survival of GBM stem cells, an unbiased pooled shRNA screen of 10,000 genes was conducted under normoxic as well as hypoxic conditions. A number of essential genes were identified that are required for GBM-SC growth, under either or both oxygen conditions, in two different GBM-SC lines. Interestingly, only about a third of the essential genes were common to both cell lines. The oxygen environment significantly impacts the cellular genetic dependencies as 30% of the genes required under hypoxia were not required under normoxic conditions. In addition to identifying essential genes already implicated in GBM such as CDK4, KIF11, and RAN, the screen also identified new genes that have not been previously implicated in GBM stem cell biology. The importance of the serum and glucocorticoid-regulated kinase 1 (SGK1) for cellular survival was validated in multiple patient-derived GBM stem cell lines using shRNA, CRISPR, and pharmacologic inhibitors. However, SGK1 depletion and inhibition has little effect on traditional serum grown glioma lines and on differentiated GBM-SCs indicating its specific importance in GBM stem cell survival.
Implications: This study identifies genes required for the growth and survival of GBM stem cells under both normoxic and hypoxic conditions and finds SGK1 as a novel potential drug target for GBM. Mol Cancer Res; 16(1); 103–14. ©2017 AACR.
http://ift.tt/2lDLleM
Differential Response of Glioma Stem Cells to Arsenic Trioxide Therapy Is Regulated by MNK1 and mRNA Translation
Mesenchymal (MES) and proneural (PN) are two distinct glioma stem cell (GSC) populations that drive therapeutic resistance in glioblastoma (GBM). We screened a panel of 650 small molecules against patient-derived GBM cells to discover compounds targeting specific GBM subtypes. Arsenic trioxide (ATO), an FDA-approved drug that crosses the blood–brain barrier, was identified as a potent PN-specific compound in the initial screen and follow-up validation studies. Furthermore, MES and PN GSCs exhibited differential sensitivity to ATO. As ATO has been shown to activate the MAPK-interacting kinase 1 (MNK1)-eukaryotic translation initiation factor 4E (eIF4E) pathway and subsequent mRNA translation in a negative regulatory feedback manner, the mechanistic role of ATO resistance in MES GBM was explored. In GBM cells, ATO-activated translation initiation cellular events via the MNK1–eIF4E signaling axis. Furthermore, resistance to ATO in intracranial PDX tumors correlated with high eIF4E phosphorylation. Polysomal fractionation and microarray analysis of GBM cells were performed to identify ATO's effect on mRNA translation and enrichment of anti-apoptotic mRNAs in the ATO-induced translatome was found. Additionally, it was determined that MNK inhibition sensitized MES GSCs to ATO in neurosphere and apoptosis assays. Finally, examination of the effect of ATO on patients from a phase I/II clinical trial of ATO revealed that PN GBM patients responded better to ATO than other subtypes as demonstrated by longer overall and progression-free survival.
Implications: These findings raise the possibility of a unique therapeutic approach for GBM, involving MNK1 targeting to sensitize MES GSCs to drugs like arsenic trioxide. Mol Cancer Res; 16(1); 32–46. ©2017 AACR.
http://ift.tt/2CqCxDv
Functional Genomics Approach Identifies Novel Signaling Regulators of TGF{alpha} Ectodomain Shedding
Ectodomain shedding of cell-surface precursor proteins by metalloproteases generates important cellular signaling molecules. Of importance for disease is the release of ligands that activate the EGFR, such as TGFα, which is mostly carried out by ADAM17 [a member of the A-disintegrin and metalloprotease (ADAM) domain family]. EGFR ligand shedding has been linked to many diseases, in particular cancer development, growth and metastasis, as well as resistance to cancer therapeutics. Excessive EGFR ligand release can outcompete therapeutic EGFR inhibition or the inhibition of other growth factor pathways by providing bypass signaling via EGFR activation. Drugging metalloproteases directly have failed clinically because it indiscriminately affected shedding of numerous substrates. It is therefore essential to identify regulators for EGFR ligand cleavage. Here, integration of a functional shRNA genomic screen, computational network analysis, and dedicated validation tests succeeded in identifying several key signaling pathways as novel regulators of TGFα shedding in cancer cells. Most notably, a cluster of genes with NFB pathway regulatory functions was found to strongly influence TGFα release, albeit independent of their NFB regulatory functions. Inflammatory regulators thus also govern cancer cell growth–promoting ectodomain cleavage, lending mechanistic understanding to the well-known connection between inflammation and cancer.
Implications: Using genomic screens and network analysis, this study defines targets that regulate ectodomain shedding and suggests new treatment opportunities for EGFR-driven cancers. Mol Cancer Res; 16(1); 147–61. ©2017 AACR.
http://ift.tt/2lDLkre
Personalized siRNA-Nanoparticle Systemic Therapy using Metastatic Lymph Node Specimens Obtained with EBUS-TBNA in Lung Cancer
Inhibiting specific gene expression with siRNA provides a new therapeutic strategy to tackle many diseases at the molecular level. Recent strategies called high-density lipoprotein (HDL)-mimicking peptide-phospholipid nanoscaffold (HPPS) nanoparticles have been used to induce siRNAs-targeted delivery to scavenger receptor class B type I receptor (SCARB1)-expressing cancer cells with high efficiency. Here, eight ideal therapeutic target genes were identified for advanced lung cancer throughout the screenings using endobronchial ultrasonography–guided transbronchial needle aspiration (EBUS-TBNA) and the establishment of a personalized siRNA-nanoparticle therapy. The relevance of these genes was evaluated by means of siRNA experiments in cancer cell growth. To establish a therapeutic model, kinesin family member-11 (KIF11) was selected as a target gene. A total of 356 lung cancers were analyzed immunohistochemically for its clinicopathologic significance. The antitumor effect of HPPS-conjugated siRNA was evaluated in vivo using xenograft tumor models. Inhibition of gene expression for these targets effectively suppressed lung cancer cell growth. SCARB1 was highly expressed in a subset of tumors from the lung large-cell carcinoma (LCC) and small-cell lung cancer (SCLC) patients. High-level KIF11 expression was identified as an independent prognostic factor in LCC and squamous cell carcinoma (SqCC) patients. Finally, a conjugate of siRNA against KIF11 and HPPS nanoparticles induced downregulation of KIF11 expression and mediated dramatic inhibition of tumor growth in vivo.
Implications: This approach showed delivering personalized cancer-specific siRNAs via the appropriate nanocarrier may be a novel therapeutic option for patients with advanced lung cancer. Mol Cancer Res; 16(1); 47–57. ©2017 AACR.
http://ift.tt/2CrL6Oi
Heat Shock Protein 70 (Hsp70) Suppresses RIP1-Dependent Apoptotic and Necroptotic Cascades
Hsp70 is a molecular chaperone that binds to "client" proteins and protects them from protein degradation. Hsp70 is essential for the survival of many cancer cells, but it is not yet clear which of its clients are involved. Using structurally distinct chemical inhibitors, we found that many of the well-known clients of the related chaperone, Hsp90, are not strikingly responsive to Hsp70 inhibition. Rather, Hsp70 appeared to be important for the stability of the RIP1 (RIPK1) regulators: cIAP1/2 (BIRC1 and BIRC3), XIAP, and cFLIPS/L (CFLAR). These results suggest that Hsp70 limits apoptosis and necroptosis pathways downstream of RIP1. Consistent with this model, MDA-MB-231 breast cancer cells treated with Hsp70 inhibitors underwent apoptosis, while cotreatment with z-VAD.fmk switched the cell death pathway to necroptosis. In addition, cell death in response to Hsp70 inhibitors was strongly suppressed by RIP1 knockdown or inhibitors. Thus, these data indicate that Hsp70 plays a previously unrecognized and important role in suppressing RIP1 activity.
Implications: These findings clarify the role of Hsp70 in prosurvival signaling and suggest IAPs as potential new biomarkers for Hsp70 inhibition. Mol Cancer Res; 16(1); 58–68. ©2017 AACR.
http://ift.tt/2CspXDx
Genomic Gain of 16p13.3 in Prostate Cancer Predicts Poor Clinical Outcome after Surgical Intervention
Identifying tumors with high metastatic potential is key to improving the clinical management of prostate cancer. Recently, we characterized a chromosome 16p13.3 gain frequently observed in prostate cancer metastases and now demonstrate the prognostic value of this genomic alteration in surgically treated prostate cancer. Dual-color FISH was used to detect 16p13.3 gain on a human tissue microarray representing 304 primary radical prostatectomy (RP) cases with clinical follow-up data. The results were validated in an external dataset. The 16p13.3 gain was detected in 42% (113/267) of the specimens scorable by FISH and was significantly associated with clinicopathologic features of aggressive prostate cancer, including high preoperative PSA (P = 0.03) levels, high Gleason score (GS, P < 0.0001), advanced pathologic tumor stage (P < 0.0001), and positive surgical margins (P = 0.009). The 16p13.3 gain predicted biochemical recurrence (BCR) in the overall cohort (log-rank P = 0.0005), and in subsets of patients with PSA ≤10 or GS ≤7 (log-rank P = 0.02 and P = 0.006, respectively). Moreover, combining the 16p13.3 gain status with standard prognostic markers improved BCR risk stratification and identified a subgroup of patients with high probability of recurrence. The 16p13.3 gain status was also associated with an increased risk of developing distant metastases (log-rank P = 0.03) further substantiating its role in prostate cancer progression.
Implications: This study demonstrates the prognostic significance of the 16p13.3 genomic gain in primary prostate tumors, suggesting potential utility in the clinical management of the disease by identifying patients at high risk of recurrence who may benefit from adjuvant therapies. Mol Cancer Res; 16(1); 115–23. ©2017 AACR.
http://ift.tt/2lF0FaU
Functional Impact of Chromatin Remodeling Gene Mutations and Predictive Signature for Therapeutic Response in Bladder Cancer
Urothelial carcinoma accounts for most of the bladder cancer cases. Using next-generation sequencing (NGS) technology, we found that a significant percentage (83%) of tumors had mutations in chromatin-remodeling genes. Here, we examined the functional relevance of mutations in two chromatin-remodeling genes, EP300 and its paralog, CREBBP, which are mutated in almost one-third of patients. Interestingly, almost half of missense mutations cluster in the histone-acetyltransferase (HAT) domain of EP300/CREBBP. This domain catalyzes the transfer of an acetyl group to target molecules such as histones, thereby regulating chromatin dynamics. Thus, patients with EP300 or CREBBP mutations may have alterations in the ability of the corresponding proteins to modify histone proteins and control transcriptional profiles. In fact, it was determined that many of the missense HAT mutations in EP300 (64%) and CREBBP (78%) were HAT-inactivating. These inactivating mutations also correlated with invasive disease in patients. Strikingly, the prediction software Mutation Assessor accurately predicted the functional consequences of each HAT missense mutation. Finally, a gene expression signature was developed that associated with loss of HAT activity and that this signature was associated with more aggressive cancer in four patient datasets. Further supporting the notion that this score accurately reflects HAT activity, we found it is responsive to treatment of cancer cells to mocetinostat, a histone deacetylase (HDAC) inhibitor.
Implication: This study provides a rationale for targeted sequencing of EP300 and CREBBP and use of a gene profiling signature for predicting therapeutic response in patients. Mol Cancer Res; 16(1); 69–77. ©2017 AACR.
http://ift.tt/2Cuvutp
Malignant Phenotypes in Metastatic Melanoma are Governed by SR-BI and its Association with Glycosylation and STAT5 Activation
Metastatic melanoma is hallmarked by elevated glycolytic flux and alterations in cholesterol homeostasis. The contribution of cholesterol transporting receptors for the maintenance of a migratory and invasive phenotype is not well defined. Here, the scavenger receptor class B type I (SCARB1/SR-BI), a high-density lipoprotein (HDL) receptor, was identified as an estimator of melanoma progression in patients. We further aimed to identify the SR-BI–controlled gene expression signature and its related cellular phenotypes. On the basis of whole transcriptome analysis, it was found that SR-BI knockdown, but not functional inhibition of its cholesterol-transporting capacity, perturbed the metastasis-associated epithelial-to-mesenchymal transition (EMT) phenotype. Furthermore, SR-BI knockdown was accompanied by decreased migration and invasion of melanoma cells and reduced xenograft tumor growth. STAT5 is an important mediator of the EMT process and loss of SR-BI resulted in decreased glycosylation, reduced DNA binding, and target gene expression of STAT5. When human metastatic melanoma clinical specimens were analyzed for the abundance of SR-BI and STAT5 protein, a positive correlation was found. Finally, a novel SR-BI–regulated gene profile was determined, which discriminates metastatic from nonmetastatic melanoma specimens indicating that SR-BI drives gene expression contributing to growth at metastatic sites. Overall, these results demonstrate that SR-BI is a highly expressed receptor in human metastatic melanoma and is crucial for the maintenance of the metastatic phenotype.
Implications: High SR-BI expression in melanoma is linked with increased cellular glycosylation and hence is essential for a metastasis-specific expression signature. Mol Cancer Res; 16(1); 135–46. ©2017 AACR.
http://ift.tt/2lF0oVq
Εγγραφή σε:
Αναρτήσεις (Atom)