Project description:Genes encoding subunits of SWI/SNF (BAF) chromatin-remodeling complexes are collectively mutated in ∼20% of all human cancers. Although ARID1A is the most frequent target of mutations, the mechanism by which its inactivation promotes tumorigenesis is unclear. Here we demonstrate that Arid1a functions as a tumor suppressor in the mouse colon, but not the small intestine, and that invasive ARID1A-deficient adenocarcinomas resemble human colorectal cancer (CRC). These tumors lack deregulation of APC/β-catenin signaling components, which are crucial gatekeepers in common forms of intestinal cancer. We find that ARID1A normally targets SWI/SNF complexes to enhancers, where they function in coordination with transcription factors to facilitate gene activation. ARID1B preserves SWI/SNF function in ARID1A-deficient cells, but defects in SWI/SNF targeting and control of enhancer activity cause extensive dysregulation of gene expression. These findings represent an advance in colon cancer modeling and implicate enhancer-mediated gene regulation as a principal tumor-suppressor function of ARID1A.
Project description:Genes encoding subunits of SWI/SNF chromatin remodeling complexes are collectively mutated in ~20% of all human cancers. Although ARID1A is the most frequent target of mutations, the mechanism by which its inactivation promotes tumorigenesis is unclear. Here, we demonstrate that Arid1a functions as a tumor suppressor in the mouse colon, but not the small intestine, and that invasive ARID1A-deficient adenocarcinomas resemble human colorectal cancer (CRC). These tumors lack deregulation of APC/beta-catenin, crucial gatekeepers in common forms of intestinal cancer. ARID1A normally targets SWI/SNF complexes to enhancers, where they function in coordination with transcription factors (TFs) to facilitate gene activation. ARID1B preserves SWI/SNF function in ARID1A-deficient cells, but defects in SWI/SNF targeting and control of enhancer activity cause extensive dysregulation of gene expression. These findings represent an advance in colon cancer modeling and implicate enhancer-mediated gene regulation as a principal tumor suppressor function of ARID1A.
Project description:Genes encoding subunits of SWI/SNF chromatin remodeling complexes are collectively mutated in ~20% of all human cancers. Although ARID1A is the most frequent target of mutations, the mechanism by which its inactivation promotes tumorigenesis is unclear. Here, we demonstrate that Arid1a functions as a tumor suppressor in the mouse colon, but not the small intestine, and that invasive ARID1A-deficient adenocarcinomas resemble human colorectal cancer (CRC). These tumors lack deregulation of APC/beta-catenin, crucial gatekeepers in common forms of intestinal cancer. ARID1A normally targets SWI/SNF complexes to enhancers, where they function in coordination with transcription factors (TFs) to facilitate gene activation. ARID1B preserves SWI/SNF function in ARID1A-deficient cells, but defects in SWI/SNF targeting and control of enhancer activity cause extensive dysregulation of gene expression. These findings represent an advance in colon cancer modeling and implicate enhancer-mediated gene regulation as a principal tumor suppressor function of ARID1A.
Project description:Genes encoding subunits of SWI/SNF chromatin remodeling complexes are collectively mutated in ~20% of all human cancers. Although ARID1A is the most frequent target of mutations, the mechanism by which its inactivation promotes tumorigenesis is unclear. Here, we demonstrate that Arid1a functions as a tumor suppressor in the mouse colon, but not the small intestine, and that invasive ARID1A-deficient adenocarcinomas resemble human colorectal cancer (CRC). These tumors lack deregulation of APC/beta-catenin, crucial gatekeepers in common forms of intestinal cancer. ARID1A normally targets SWI/SNF complexes to enhancers, where they function in coordination with transcription factors (TFs) to facilitate gene activation. ARID1B preserves SWI/SNF function in ARID1A-deficient cells, but defects in SWI/SNF targeting and control of enhancer activity cause extensive dysregulation of gene expression. These findings represent an advance in colon cancer modeling and implicate enhancer-mediated gene regulation as a principal tumor suppressor function of ARID1A.
Project description:Genes encoding subunits of SWI/SNF chromatin remodeling complexes are collectively mutated in ~20% of all human cancers. Although ARID1A is the most frequent target of mutations, the mechanism by which its inactivation promotes tumorigenesis is unclear. Here, we demonstrate that Arid1a functions as a tumor suppressor in the mouse colon, but not the small intestine, and that invasive ARID1A-deficient adenocarcinomas resemble human colorectal cancer (CRC). These tumors lack deregulation of APC/beta-catenin, crucial gatekeepers in common forms of intestinal cancer. ARID1A normally targets SWI/SNF complexes to enhancers, where they function in coordination with transcription factors (TFs) to facilitate gene activation. ARID1B preserves SWI/SNF function in ARID1A-deficient cells, but defects in SWI/SNF targeting and control of enhancer activity cause extensive dysregulation of gene expression. These findings represent an advance in colon cancer modeling and implicate enhancer-mediated gene regulation as a principal tumor suppressor function of ARID1A.
Project description:Mutations in genes encoding SWI/SNF chromatin remodeling complexes are found in approximately 20% of all human cancers, with ARID1A being the most frequently mutated subunit. Here, we show that disruption of ARID1A homologs in a zebrafish model accelerates the onset and increases the penetrance of MYCN-driven neuroblastoma by increasing cell proliferation in the sympathoadrenal lineage. Depletion of ARID1A in human NGP neuroblastoma cells promoted the adrenergic-to-mesenchymal transition with changes in enhancer-mediated gene expression due to alterations in the genomic occupancies of distinct SWI/SNF assemblies, BAF and PBAF. Our findings indicate that ARID1A is a haploinsufficient tumor suppressor in MYCN-driven neuroblastoma, whose depletion enhances tumor development and promotes the emergence of the more drug-resistant mesenchymal cell state.
Project description:Nonalcoholic steatohepatitis (NASH) is a rapidly growing cause of chronic liver damage, cirrhosis, and hepatocellular carcinoma. How fatty liver pathogenesis is subject to epigenetic regulation is unknown. We hypothesized that chromatin remodeling is important for the pathogenesis of fatty liver disease. AT-rich interactive domain-containing protein 1A (ARID1A), a DNA-binding component of the SWItch/sucrose nonfermentable adenosine triphosphate-dependent chromatin-remodeling complex, contributes to nucleosome repositioning and access by transcriptional regulators. Liver-specific deletion of Arid1a (Arid1a liver knockout [LKO]) caused the development of age-dependent fatty liver disease in mice. Transcriptome analysis revealed up-regulation of lipogenesis and down-regulation of fatty acid oxidation genes. As evidence of direct regulation, ARID1A demonstrated direct binding to the promoters of many of these differentially regulated genes. Additionally, Arid1a LKO mice were more susceptible to high-fat diet-induced liver steatosis and fibrosis. We deleted Pten in combination with Arid1a to synergistically drive fatty liver progression. Inhibition of lipogenesis using CAT-2003, a potent sterol regulatory element-binding protein inhibitor, mediated improvements in markers of fatty liver disease progression in this Arid1a/Pten double knockout model. Conclusion: ARID1A plays a role in the epigenetic regulation of hepatic lipid homeostasis, and its suppression contributes to fatty liver pathogenesis. Combined Arid1a and Pten deletion shows accelerated fatty liver disease progression and is a useful mouse model for studying therapeutic strategies for NASH.
Project description:Background & aimsEpigenetic processes regulating gene expression contribute markedly to epithelial cell plasticity in colorectal carcinogenesis. The lysine methyltransferase SUV420H2 comprises an important regulator of epithelial plasticity and is primarily responsible for trimethylation of H4K20 (H4K20me3). Loss of H4K20me3 has been suggested as a hallmark of human cancer due to its interaction with DNMT1. However, the role of Suv4-20h2 in colorectal cancer is unknown.MethodsWe examined the alterations in histone modifications in patient-derived colorectal cancer organoids. Patient-derived colorectal cancer organoids and mouse intestinal organoids were genetically manipulated for functional studies in patient-derived xenograft and orthotopic transplantation. Gene expression profiling, micrococcal nuclease assay, and chromatin immunoprecipitation were performed to understand epigenetic regulation of chromatin states and gene expression in patient-derived and mouse intestinal organoids.ResultsWe found that reduced H4K20me3 levels occurred predominantly in right-sided patient-derived colorectal cancer organoids, which were associated with increased chromatin accessibility. Re-compaction of chromatin by methylstat, a histone demethylase inhibitor, resulted in reduced growth selectively in subcutaneously grown tumors derived from right-sided cancers. Using mouse intestinal organoids, we confirmed that Suv4-20h2-mediated H4K20me3 is required for maintaining heterochromatin compaction and to prevent R-loop formation. Cross-species comparison of Suv4-20h2-depleted murine organoids with right-sided colorectal cancer organoids revealed a large overlap of gene signatures involved in chromatin silencing, DNA methylation, and stemness/Wnt signaling.ConclusionsLoss of Suv4-20h2-mediated H4K20me3 drives right-sided colorectal tumorigenesis through an epigenetically controlled mechanism of chromatin compaction. Our findings unravel a conceptually novel approach for subtype-specific therapy of this aggressive form of colorectal cancer.
Project description:DNMT3A, the gene encoding the de novo DNA methyltransferase 3A, is among the most frequently mutated genes in hematologic malignancies. However, the mechanisms through which DNMT3A normally suppresses malignancy development are unknown. Here, we show that DNMT3A loss synergizes with the FLT3 internal tandem duplication in a dose-influenced fashion to generate rapid lethal lymphoid or myeloid leukemias similar to their human counterparts. Loss of DNMT3A leads to reduced DNA methylation, predominantly at hematopoietic enhancer regions in both mouse and human samples. Myeloid and lymphoid diseases arise from transformed murine hematopoietic stem cells. Broadly, our findings support a role for DNMT3A as a guardian of the epigenetic state at enhancer regions, critical for inhibition of leukemic transformation.