Project description:Small cell carcinoma of the ovary-hypercalcemic type (SCCOHT) is a rare and aggressive form of ovarian cancer afflicting young women at a median age of 24 years. SCCOHTs are characterized by loss of protein expression of SWI/SNF chromatin remodeling ATPases SMARCA4 and SMARCA2 through mutation and epigenetic silencing, respectively. This study aims to establish gene expression profiles of this cancer through RNA-Seq of four pathologically confirmed cases of SCCOHT tumors.
Project description:<p>Small cell carcinoma of the ovary-hypercalcemic type (SCCOHT) is a rare and aggressive form of ovarian cancer afflicting young women at a median age of 24 years. SCCOHTs are characterized by loss of protein expression of SWI/SNF chromatin remodeling ATPases SMARCA4 and SMARCA2 through mutation and epigenetic silencing, respectively. This study aims to establish gene expression profiles of this cancer through RNA-Seq of four pathologically confirmed cases of SCCOHT tumors.</p>
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 BRG1 loss plays in SCCOHT tumorigenesis, we performed integrative multi-omic analyses in SCCOHT cell lines +/- BRG1 re-expression. BRG1 re-expression induced a gene and protein signature similar to an epithelial cell and gained chromatin accessibility sites correlated with other epithelial originating TCGA tumors. Furthermore, AP-1 motifs were enriched at the promoters of highly upregulated epithelial genes. Using a dominant negative AP-1 cell line, we found that both AP-1 DNA binding activity and BRG1 re-expression are necessary for the gene and protein expression of epithelial genes. Our study demonstrates that BRG1 re-expression drives an epithelial-like gene and protein signature in SCCOHT cells that depends upon AP-1 activity.
Project description:Inactivating mutations in SMARCA4 (BRG1), a key SWI/SNF chromatin remodelling gene, underlie small cell carcinoma of the ovary, hypercalcemic type (SCCOHT). To reveal its druggable vulnerabilities, we perform kinase-focused RNAi screens and uncover that SMARCA4-deficient SCCOHT cells are highly sensitive to the inhibition of cyclin-dependent kinase 4/6 (CDK4/6). SMARCA4 loss causes profound downregulation of cyclin D1, which limits CDK4/6 kinase activity in SCCOHT cells and leads to in vitro and in vivo susceptibility to CDK4/6 inhibitors. SCCOHT patient tumors are deficient in cyclin D1 yet retain the retinoblastoma-proficient/p16INK4a-deficient profile associated with positive responses to CDK4/6 inhibitors. Thus, our findings indicate that CDK4/6 inhibitors, approved for a breast cancer subtype addicted to CDK4/6 activation, could be repurposed to treat SCCOHT. Moreover, our study suggests a novel paradigm whereby critically low oncogene levels, caused by loss of a driver tumor suppressor, may also be exploited therapeutically.
Project description:Inactivating mutations in SMARCA4 (BRG1), a key SWI/SNF chromatin remodelling gene, underlie small cell carcinoma of the ovary, hypercalcemic type (SCCOHT). To reveal its druggable vulnerabilities, we perform kinase-focused RNAi screens and uncover that SMARCA4-deficient SCCOHT cells are highly sensitive to the inhibition of cyclin-dependent kinase 4/6 (CDK4/6). SMARCA4 loss causes profound downregulation of cyclin D1, which limits CDK4/6 kinase activity in SCCOHT cells and leads to in vitro and in vivo susceptibility to CDK4/6 inhibitors. SCCOHT patient tumors are deficient in cyclin D1 yet retain the retinoblastoma-proficient/p16INK4a-deficient profile associated with positive responses to CDK4/6 inhibitors. Thus, our findings indicate that CDK4/6 inhibitors, approved for a breast cancer subtype addicted to CDK4/6 activation, could be repurposed to treat SCCOHT. Moreover, our study suggests a novel paradigm whereby critically low oncogene levels, caused by loss of a driver tumor suppressor, may also be exploited therapeutically.
Project description:Small cell carcinoma of the ovary of hypercalcemic type (SCCOHT) is an extremely rare, aggressive cancer affecting children and young women. We identified germline and somatic inactivating mutations in the SWI/SNF chromatin-remodeling gene SMARCA4 in 75% (9/12) of SCCOHT patients in addition to SMARCA4 protein loss in 82% (14/17) of SCCOHT tumors, but in only 0.4% (2/485) of other primary ovarian tumors. These data implicate SMARCA4 in SCCOHT oncogenesis.
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 BRG1 loss plays in SCCOHT tumorigenesis, we performed integrative multi-omic analyses in a SCCOHT cell line +/- BRG1 re-expression. BRG1 re-expression induced a gene and protein signature similar to an epithelial cell and gained chromatin accessibility sites correlated with other epithelial originating TCGA tumors. Gained chromatin accessibility and BRG1 recruited sites were strongly enriched for transcription factor binding motifs of AP-1 family members. Furthermore, AP-1 motifs were enriched at the promoters of highly upregulated epithelial genes. Using a dominant negative AP-1 cell line, we found that both AP-1 DNA binding activity and BRG1 re-expression are necessary for the gene and protein expression of epithelial genes. Our study demonstrates that the BRG1 re-expression drives an epithelial-like gene and protein signature in SCCOHT cells that depends upon by AP-1 activity.
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 BRG1 loss plays in SCCOHT tumorigenesis, we performed integrative multi-omic analyses in a SCCOHT cell line +/- BRG1 re-expression. BRG1 re-expression induced a gene and protein signature similar to an epithelial cell and gained chromatin accessibility sites correlated with other epithelial originating TCGA tumors. Gained chromatin accessibility and BRG1 recruited sites were strongly enriched for transcription factor binding motifs of AP-1 family members. Furthermore, AP-1 motifs were enriched at the promoters of highly upregulated epithelial genes. Using a dominant negative AP-1 cell line, we found that both AP-1 DNA binding activity and BRG1 re-expression are necessary for the gene and protein expression of epithelial genes. Our study demonstrates that the BRG1 re-expression drives an epithelial-like gene and protein signature in SCCOHT cells that depends upon by AP-1 activity.
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 BRG1 loss plays in SCCOHT tumorigenesis, we performed integrative multi-omic analyses in a SCCOHT cell line +/- BRG1 re-expression. BRG1 re-expression induced a gene and protein signature similar to an epithelial cell and gained chromatin accessibility sites correlated with other epithelial originating TCGA tumors. Gained chromatin accessibility and BRG1 recruited sites were strongly enriched for transcription factor binding motifs of AP-1 family members. Furthermore, AP-1 motifs were enriched at the promoters of highly upregulated epithelial genes. Using a dominant negative AP-1 cell line, we found that both AP-1 DNA binding activity and BRG1 re-expression are necessary for the gene and protein expression of epithelial genes. Our study demonstrates that the BRG1 re-expression drives an epithelial-like gene and protein signature in SCCOHT cells that depends upon by AP-1 activity.