Identification of ZIC5 as a Survival Factor of Prostate and Colorectal Cancer Cells

Summary

The identification of specific drug targets is very important for cancer therapy. We recently identified zinc finger protein of the cerebellum 5 (ZIC5) as a factor that promotes melanoma aggressiveness via platelet-derived growth factor D (PDGFD) expression. However, its roles in other cancer types remain largely unknown. Here we determined the roles of ZIC5 in prostate cancer (PCa) and colorectal cancer (CRC) cells. The results showed that ZIC5 was highly expressed in CRC and dedifferentiated PCa tissues, whereas little expression was observed in relevant normal tissues. Knockdown of ZIC5 decreased the proliferation of several PCa and CRC cell lines with induction of cell death. ZIC5 knockdown significantly suppressed PDGFD expression transcriptionally, and PDGFD suppression also decreased the proliferation of PCa and CRC cell lines. In addition, suppression of ZIC5 or PDGFD expression decreased levels of phosphorylated focal adhesion kinase (FAK) and signal transducer and activator of transcription 3 (STAT3) which are associated with PCa and CRC aggressiveness. Furthermore, knockdown of ZIC5 or PDGFD enhanced the death of PCa and CRC cells induced by the anti-cancer drugs docetaxel or oxaliplatin, respectively. These results suggest that ZIC5 and PDGFD promote the survival of PCa and CRC cells with enhancing FAK and STAT3 activity, and that the roles of ZIC5 are consistent across several cancer types.

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