Mutations in the SWI/SNF chromatin remodeling complex induce metabolic rewiring and dependence on oxidative phosphorylation [Affymetrix]
Ontology highlight
ABSTRACT: 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-α. 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.
Project description: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-α. 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.
Project description:The SWI/SNF chromatin remodeling complex is altered in ~20% of human cancers. ARID1A, a component of the SWI/SNF chromatin-remodeling complex, is the most frequently mutated epigenetic regulator in human cancers. Inactivation of the SWI/SNF complex is synthetically lethal with inhibition of EZH2 activity. EZH2 inhibitors are entering clinical trials for specific tumor types with SWI/SNF mutations. However, mechanisms of de novo or acquired resistance to EZH2 inhibitors in cancers with inactivating SWI/SNF mutations are unknown. Here we show that the switch of the SWI/SNF catalytic subunits from SMARCA4 to SMARCA2 drives resistance to EZH2 inhibitors in ARID1A-mutated ovarian cancer cells.
Project description:The SWI/SNF chromatin remodeling complex is altered in ~20% of human cancers. ARID1A, a component of the SWI/SNF chromatin-remodeling complex, is the most frequently mutated epigenetic regulator in human cancers. Inactivation of the SWI/SNF complex is synthetically lethal with inhibition of EZH2 activity. EZH2 inhibitors are entering clinical trials for specific tumor types with SWI/SNF mutations. However, mechanisms of de novo or acquired resistance to EZH2 inhibitors in cancers with inactivating SWI/SNF mutations are unknown. Here we show that the switch of the SWI/SNF catalytic subunits from SMARCA4 to SMARCA2 drives resistance to EZH2 inhibitors in ARID1A-mutated ovarian cancer cells.
Project description:Here we performed transcriptional profiling of the prostate cancer cell lines LNCaP and 22Rv1 comparing non-targeting siRNA treatment versus siRNAs targeting SWI/SNF complex proteins (SMARCA2, SMARCA4, and SMARCB1). Goal was to determine the effect of SWI/SNF knockdown on gene expression in prostate cancer. Two-condition experiment: non-targeting siRNA versus SWI/SNF-siRNA treated cells. Three SWI/SNF proteins were targeted: SMARCA2, SMARCA4, and SMARB1. Biological replicates: 1 control replicate, 2 treatment replicates per SWI/SNF protein. Technical replicates: 1 replicate per SWI/SNF protein. Cell lines: 22Rv1 and LNCaP.
Project description:SMARCA2 and SMARCA4 are two mutually exclusive ATPase subunits of SWI/SNF complex. SMARCA4 deficient lung cancer population selectively depend on SMARCA2 for cancer growth phenotype. Rescue experiments with ectopic expression of wild-type, bromodomain mutant and ATPase dead SMARCA2 and SMARCA4 highlight that ATPase domain is the drug target. In this study, we performed genome-wide microarray and differential gene expression profiling on isogenic lung cancer lines expressing cDNA rescue constructs for wild-type, bromodomain mutant and ATPase dead SMARCA2 and SMARCA4
Project description:Mammalian SWI/SNF complexes are considered as key epigenetic regulators and they are recurrently mutated in many types of cancer. Most of the studies of these chromatin remodeling complexes are focused on their role in regulating protein-coding genes. However, here we show that the SWI/SNF complex is able to control the expression of microRNAs. We used a SMARCA4-deficient model of lung adenocarcinoma where we could track changes of the miRNome upon SMARCA4 restoration. We found that exogenous SMARCA4 was successfully incorporated into endogenous SWI/SNF complexes and that these SMARCA4-SWI/SNF complexes induced significant changes in the expression of cancer-related microRNAs. The most significantly dysregulated miRNA was miR-222, whose expression was promoted by SMARCA4-SWI/SNF complexes but not by SMARCA2-SWI/SNF complexes via their direct binding to a miR-222 enhancer region. Importantly, miR-222 expression decreased cell viability and impaired cell clonogenicity, phenocopying the tumor-suppressor role of the SMARCA4-SWI/SNF complex in lung cancer. Finally, we showed that the miR-222 enhancer does not interact with any cancer-related protein-coding genes, supporting that its tumor suppressor effect may be exerted via miR-222. Overall, this study highlights the relevant role of the SWI/SNF complex in regulating the expression of the non-coding genome.
Project description:Lung cancer is the top cause of cancer mortality. Despite recent advances, the majority of patients with lung cancer still lack effective therapeutic options, underscoring the dire need for additional treatment approaches. Genomic studies have identified frequent mutations in subunits of the SWI/SNF chromatin remodeling complex including SMARCA4 and ARID1A in non-small cell lung cancer with a frequency of up to 33% in advanced stage disease, making it the most frequently mutated complex in lung cancer. Recent reports have identified the paralogue SMARCA2 to be synthetic lethal to SMARCA4 suggesting SMARCA2 is a valuable therapeutic target. However, the discovery of selective inhibitors of SMARCA2 has been challenging. To overcome this hurdle, we have utilized iterative structure-activity relationship (SAR) studies to develop novel, potent and selective SMARCA2 degrading small molecules based on proteolysis targeting chimera (PROTAC) technology. We demonstrated that YD23, our lead SMARCA2 PROTAC, potently and selectively induces degradation of SMARCA2. Mechanistically, we show that SMARCA2 degradation in SMARCA4-mutant cells induces a profound reprograming of the enhancer landscape with marked loss of chromatin accessibility at enhancers of genes involved in cell proliferation. Furthermore, we identified nuclear effectors of the Hippo pathway, YAP/TEAD, as key co-conspirators of SMARCA2 in driving the growth of SMARCA4-mutant cancer cells that can be disrupted by our degrader. Finally, we show that YD23 has a potent tumor growth inhibitory activity in SMARCA4-mutant xenograft tumors. These findings provide the mechanistic basis for development of SMARCA2 degraders as synthetic lethal therapeutics against SMARCA4 mutant tumors.
Project description:Lung cancer is the top cause of cancer mortality. Despite recent advances, the majority of patients with lung cancer still lack effective therapeutic options, underscoring the dire need for additional treatment approaches. Genomic studies have identified frequent mutations in subunits of the SWI/SNF chromatin remodeling complex including SMARCA4 and ARID1A in non-small cell lung cancer with a frequency of up to 33% in advanced stage disease, making it the most frequently mutated complex in lung cancer. Recent reports have identified the paralogue SMARCA2 to be synthetic lethal to SMARCA4 suggesting SMARCA2 is a valuable therapeutic target. However, the discovery of selective inhibitors of SMARCA2 has been challenging. To overcome this hurdle, we have utilized iterative structure-activity relationship (SAR) studies to develop novel, potent and selective SMARCA2 degrading small molecules based on proteolysis targeting chimera (PROTAC) technology. We demonstrated that YD23, our lead SMARCA2 PROTAC, potently and selectively induces degradation of SMARCA2. Mechanistically, we show that SMARCA2 degradation in SMARCA4-mutant cells induces a profound reprograming of the enhancer landscape with marked loss of chromatin accessibility at enhancers of genes involved in cell proliferation. Furthermore, we identified nuclear effectors of the Hippo pathway, YAP/TEAD, as key co-conspirators of SMARCA2 in driving the growth of SMARCA4-mutant cancer cells that can be disrupted by our degrader. Finally, we show that YD23 has a potent tumor growth inhibitory activity in SMARCA4-mutant xenograft tumors. These findings provide the mechanistic basis for development of SMARCA2 degraders as synthetic lethal therapeutics against SMARCA4 mutant tumors.
Project description:Lung cancer is the top cause of cancer mortality. Despite recent advances, the majority of patients with lung cancer still lack effective therapeutic options, underscoring the dire need for additional treatment approaches. Genomic studies have identified frequent mutations in subunits of the SWI/SNF chromatin remodeling complex including SMARCA4 and ARID1A in non-small cell lung cancer with a frequency of up to 33% in advanced stage disease, making it the most frequently mutated complex in lung cancer. Recent reports have identified the paralogue SMARCA2 to be synthetic lethal to SMARCA4 suggesting SMARCA2 is a valuable therapeutic target. However, the discovery of selective inhibitors of SMARCA2 has been challenging. To overcome this hurdle, we have utilized iterative structure-activity relationship (SAR) studies to develop novel, potent and selective SMARCA2 degrading small molecules based on proteolysis targeting chimera (PROTAC) technology. We demonstrated that YD23, our lead SMARCA2 PROTAC, potently and selectively induces degradation of SMARCA2. Mechanistically, we show that SMARCA2 degradation in SMARCA4-mutant cells induces a profound reprograming of the enhancer landscape with marked loss of chromatin accessibility at enhancers of genes involved in cell proliferation. Furthermore, we identified nuclear effectors of the Hippo pathway, YAP/TEAD, as key co-conspirators of SMARCA2 in driving the growth of SMARCA4-mutant cancer cells that can be disrupted by our degrader. Finally, we show that YD23 has a potent tumor growth inhibitory activity in SMARCA4-mutant xenograft tumors. These findings provide the mechanistic basis for development of SMARCA2 degraders as synthetic lethal therapeutics against SMARCA4 mutant tumors.
Project description:Small cell carcinoma of the ovary, hypercalcemic type (SCCOHT) is a rare and aggressive form of ovarian cancer. SCCOHT tumors have inactivating mutations in SMARCA4 (BRG1), one of the two mutually exclusive ATPases of the SWI/SNF chromatin remodeling complex. To address the role that SMARCA4 loss plays in SCCOHT tumorigenesis, we performed RNA-seq in a SCCOHT cell line +/- SMARCA4 re-expression. SMARCA4 re-expression was acheived by integration of pIND20-BRG1 and inducing with doxycycline. The goal of this study was to generate a high sequencing depth RNA-seq dataset to determine how restoration of SMARCA4 results in changes in gene expression and RNA splicing.