Project description:Rhabdomyosarcoma (RMS) is a pediatric malignancy of mesenchymal origin. Fusion Negative-RMS (FN-RMS) tumors are associated with RAS-pathway activation. RMS tumors express pro-differentiation myogenic transcription factors MYOD and MYOG, yet why they are unable to differentiate is poorly understood. Here we show that SNAI2 is highly expressed in FN-RMS, is regulated by MYOD and blocks myogenic differentiation promoting growth. Molecularly, SNAI2 preferentially binds E-Box-associated enhancer elements and represses expression by dampening enhancer function. SNAI2 inhibits MYOD at a subset of myogenic enhancers associated with terminal differentiation. Functional dissection demonstrates SNAI2 suppresses a MYOG, MEF2 and CDKN1A differentiation program. SNAI2 knockdown transcriptionally mimics a chemical blockade of the mutant RAS signal in FN-RMS, providing new insight connecting the genetic and epigenetic causes of this disease.
Project description:Trametinib-treated rhabdomyosarcoma cells undergo transcriptional reprogramming akin to myogenic differentiation. This reprogramming is induced by loss of ERK-mediated inhibition of MYOG expression. Restoration of MYOG allows establishment of super-enhancers at genes expressed by terminally differentiated myotubes. Our findings demonstrate that aberrant MAP kinase activity blocks differentiation in rhabdomyosarcoma and highlight trametinib as a potential therapeutic for RAS-mutated rhabdomyosarcoma.
Project description:Trametinib-treated rhabdomyosarcoma cells undergo transcriptional reprogramming akin to myogenic differentiation. This reprogramming is induced by loss of ERK-mediated inhibition of MYOG expression. Restoration of MYOG allows establishment of super-enhancers at genes expressed by terminally differentiated myotubes. Our findings demonstrate that aberrant MAP kinase activity blocks differentiation in rhabdomyosarcoma and highlight trametinib as a potential therapeutic for RAS-mutated rhabdomyosarcoma.
Project description:ATAC-seq associates impairment of myogenic differentiation in cells with an IDH2 mutation with differences in chromatin accessibility. Differences are especially apparent in regions flanking binding sites for myogenic regulatory factors and key myogenesis noncoding RNA linc-MD1. Oncogenic IDH1/2 mutations produce 2-hydroxyglutarate (2HG), resulting in competitive inhibition of DNA and protein demethylation. IDH-mutant cancer cells show an inability to differentiate but whether 2HG accumulation is sufficient to perturb differentiation directed by lineage-specifying transcription factors is unknown. A MyoD-driven model was used to study the role of IDH mutations in the differentiation of mesenchymal cells. The presence of 2HG produced by oncogenic IDH2 blocks the ability of MyoD to drive differentiation into myotubes. DNA 5mC hypermethylation is dispensable while H3K9 hypermethylation is required for this differentiation block. IDH2-R172K mutation results in H3K9 hypermethylation and impaired accessibility at myogenic chromatin regions but does not result in genome-wide decrease in accessibility. The results demonstrate the ability of the oncometabolite to 2HG block transcription factor-mediated differentiation in a molecularly defined system.
