KRAS-dependent suppression of MYC enhances the sensitivity of cancer cells to cytotoxic agents.

// Irene Ischenko 1 , Jizu Zhi 2 , Michael J. Hayman 1 , Oleksi Petrenko 1 1 Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11794, USA 2 Department of Pathology, Stony Brook University, Stony Brook, NY 11794, USA Correspondence to: Oleksi Petrenko, email: alexei.petrenko@stonybrook.edu Michael J. Hayman, email: michael.hayman@stonybrook.edu Keywords: NSCLC, KRAS, MYC, MAPK, cytotoxicity Received: September 13, 2016     Accepted: December 26, 2016     Published: February 01, 2017 ABSTRACT KRAS is the most commonly mutated oncogene, frequently associated with some of the deadliest forms of cancer. However, the need for potent and specific KRAS inhibitors remains unmet. Here, we evaluated the effects of selected cytotoxic agents on oncogenic KRAS signaling and drug response. The data provided new insights into the functional interaction between the KRAS and MYC pathways and revealed key differences between WT and mutant KRAS expressing cells. Systematic investigation of non-small cell lung cancer cell lines revealed that KRAS mutation can paradoxically increase the sensitivity of cells to cytotoxic agents. We identify MYC as a key regulator of the cellular stress responses and tumor cell viability as MYC expression was suppressed in drug-sensitive but not resistant cells. Furthermore, this suppression was driven by hyperactive KRAS/MAPK signaling. Our findings support a direct link between MYC and cancer cell viability, and raise the possibility that inactivation of MYC may be an effective therapeutic strategy for KRAS mutant tumors across various cancer types.