GSE109020
Mutations in the SWI/SNF chromatin remodeling complex induce metabolic rewiring and dependence on oxidative phosphorylation
Lung cancer is a devastating disease that remains the top cause of cancer mortality. While targeted therapies against EGFR and EML4-ALK fusion and recent advances in immunotherapy have shown substantial clinical benefit for some patients, the vast majority of patients with lung cancer still lack effective therapies underscoring the dire need for more context-specific therapeutics. Cancer genomic studies have identified frequent genetic alterations in chromatin and epigenetic regulators including inactivating mutations in components of the SWI/SNF chromatin remodeling complex. In lung adenocarcinoma, about 20% of tumors have inactivating mutations in components of the SWI/SNF chromatin remodeling complex including SMARCA4 and ARID1A. With the aim of understanding the mechanism of tumor development driven by mutations in this complex, we developed a genetically engineered mouse (GEM) model of lung adenocarcinoma by selectively ablating Smarca4 in the lung epithelium. We demonstrate that Smarca4 acts as a bona fide tumor suppressor and cooperates with p53 loss and Kras activation. Cross species integrative gene expression analyses revealed signature of enhanced oxidative phosphorylation (OXPHOS) in SMARCA4 mutant murine as well as human lung adenocarcinomas. We further show that SMARCA4 mutant cells have increased oxygen consumption and increased respiratory capacity primarily driven by increased expression of the mitochondrial master regulator, PGC1-a. Importantly, we show that SMARCA4 and other SWI/SNF mutant lung cancer cell lines and xenograft tumors have exquisite sensitivity to inhibition of OXPHOS by a novel small molecule, IACS-010759, that is under clinical development. Mechanistically, we show that SMARCA4 deficient cells have a blunted transcriptional response to energy stress creating a therapeutically attractive collateral vulnerability. These findings provide the mechanistic basis for further development of OXPHOS inhibitors as therapeutics against SWI/SNF mutant tumors. Overall design: Examination of genomic localization of SMARCA4 in H1299 cells stably transduced with an inducible SMARCA4 vector upon doxycycline adminstration to induce expression of SMARCA4.