Project description:The goal of this study is to explore the underlying mechanism which contributes to chemoresistance in high-grade serous carcinoma (HGSC) with low SMARCA4 and high SMARCA2 expression.
Project description:The goal of this study is to explore the underlying mechanism which contributes to chemoresistance in high-grade serous carcinoma (HGSC) with low SMARCA4 and high SMARCA2 expression.
Project description:Using ChIP-seq, we identified the genome-wide occupancy of SMARCA2 and SMARCA4 in lung cancer cells (NCI-H1944) reconstituted with SMARCA4 WT. We also determined how SMARCA4 occupancy changed in NCI-H1944 after SMARCA2 depletion.
Project description:The mammalian SWI/SNF helicase SMARCA4 is frequently mutated in cancer and inactivation results in a cellular dependence on its paralog, SMARCA2, thus making SMARCA2 an attractive synthetic lethal target. However, published data indicates that achieving a high degree of SMARCA2 selectivity is likely essential to afford an acceptable therapeutic index and this has been a considerable challenge due to the homology between paralogs. Herein we report the discovery of the first potent and selective SMARCA2 proteolysis-targeting chimera (PROTAC) molecule. Selective degradation was achieved in the absence of selective PROTAC binding and translated to potent in vitro growth inhibition and in vivo efficacy in SMARCA4 mutant models, compared to wild type models. Global ubiquitin mapping and proteome profiling revealed no unexpected off-target degradation. Our study thus highlights the ability to transform a non-selective SMARCA2-binding ligand into a selective and efficacious in vivo SMARCA2 PROTAC, providing a potential therapeutic opportunity for SMARCA4 mutant patients.
Project description:Using ATAC-seq, we identified the accessibility changes in lung cancer cells (NCI-H1944) reconstituted with SMARCA4 WT or SMARCA4 mutants. We also determined the SMARCA2-regulated accessibility program in NCI-H1944 after SMARCA2 depletion. Lastly, we identified the SMARCA2 accessibility program that is rescued by SMARCA4 WT and mutants. The "SAMPLE_ID" sample characteristic is a sample identifier internal to Genentech.
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 multi-subunit chromatin remodeling complexes associated with an ATPase, either SMARCA4 or SMARCA2. Heterozygous mutations in the SMARCA2 ATPase cause Nicolaides-Baraitser Syndrome (NCBRS), an intellectual disability syndrome associated with delayed speech onset. We engineered human embryonic stem cells (hESCs) to carry NCBRS-associated heterozygous SMARCA2 K755R or R1159Q mutations. While SMARCA2 mutant hESCs were phenotypically normal, differentiation to neural progenitors cells (NPCs) was severely impaired. We find that SMARCA2 mutations cause enhancer reorganization with loss of SOX3-dependent neural enhancers and prominent emergence of astrocyte-specific de novo enhancers. Changes in chromatin accessibility at enhancers were associated with an increase in SMARCA2 binding and retargeting of SMARCA4. We show that AP-1 family member FRA2 is aberrantly overexpressed in SMARCA2 mutant NPCs, where it functions as a pioneer factor at de novo enhancers. Together, our results demonstrate SMARCA2 mutations cause impaired differentiation through enhancer reprogramming via inappropriate targeting of SMARCA4.
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.