S-nitrosylation of cIAP1 switches cancer cell fate from TNF{alpha}/TNFR1-mediated cell survival to cell death.

Tumor necrosis factor alpha (TNFα) is a prominent proinflammatory cytokine and a critical mediator for the development of many types of cancer such as breast, colon, prostate, cervical, skin, liver, and chronic lymphocytic leukemia. Binding of TNFα to TNFR1 can lead to divergent signaling pathways promoting predominantly NF-kB activation but also cell death. We report here that the nitric oxide donor glyceryl trinitrate (GTN) converts TNFα, generated from immune cells or cancer cells stimulated by chemotherapy, into a pro-death mediator in colon and mammary cancer cells. GTN-mediated S-nitrosylation of cIAP1 on cysteines 571 and 574 inhibited its E3 ubiquitin ligase activity, which in turn reduced Lys-63-linked ubiquitination of RIP1 and initiated assembly of a death complex. These findings provide insights into how nitric oxide can harness advantageous aspects of inflammation in cancer and provide new therapeutic strategies.

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