Conclusion
Our results indicate that the necroptosis pathway is suppressed in lung cancer through RIP3 promoter methylation, and reactivating this pathway should be exploited for improving lung cancer chemotherapy.
Methods
In vitro cell culture and in vivo xenograft tumor therapy models and clinical sample studies are combined in studying the role of necroptosis in chemotherapy and mechanism of necroptosis suppression involving RIP3 expression regulation.
Results
While chemotherapeutic drugs were able to induce necroptotic cell death, this pathway was suppressed in lung cancer cells at least partly through downregulation of RIP3 expression. Ectopic RIP3 expression significantly sensitized lung cancer cells to the cytotoxicity of anticancer drugs such as cisplatin, etoposide, vincristine, and adriamycin. In addition, RIP3 suppression was associated with RIP3 promoter methylation, and demethylation partly restored RIP3 expression and increased chemotherapeutic-induced necroptotic cell death. In a xenograft tumor therapy model, ectopic RIP3 expression significantly sensitized anticancer activity of cisplatin in vivo. Furthermore, lower RIP3 expression was associated with worse chemotherapy response in NSCLC patients.