ABSTRACT: Sarcomas are derailed in pathways that specify mesenchymal lineages during embryogenesis, causing tumor cells to stall at early stages of differentiation. Among them, rhabdomyosarcoma (RMS) is a pediatric soft tissue sarcoma of skeletal muscle origin. A key feature of RMS is their inability to terminally differentiate despite the high expression of master myogenic regulator MYOD. The bHLH transcription factor TWIST2, which governs mesenchymal stem cell identity and restricts myogenesis, is overexpressed in patient fusion-negative RMS (FN-RMS) tumors. We show that knockdown of TWIST2 enables FN-RMS cells to exit the cell cycle and undergo myogenic differentiation, thereby reducing the growth of FN-RMS xenograft tumors. ChIP-seq analysis revealed that most TWIST2-mediated gene regulation occurs independent of changes in MYOD binding in FN-RMS cells. Instead, TWIST2 controls the deposition of H3K27 acetylation at distal enhancers by interacting with the chromatin remodelers, SMARCA4 and CHD3, to activate growth-related and repress myogenesis-related TWIST2 target genes. Our findings provide new insights into the role of TWIST2 in maintaining an undifferentiated and tumorigenic state of FN-RMS and highlight the clinical potential of reversing the TWIST2-regulated phenotype.
Project description:Sarcomas are derailed in pathways that specify mesenchymal lineages during embryogenesis, causing tumor cells to stall at early stages of differentiation. Among them, rhabdomyosarcoma (RMS) is a pediatric soft tissue sarcoma of skeletal muscle origin. A key feature of RMS is their inability to terminally differentiate despite the high expression of master myogenic regulator MYOD. The bHLH transcription factor TWIST2, which governs mesenchymal stem cell identity and restricts myogenesis, is overexpressed in patient fusion-negative RMS (FN-RMS) tumors. We show that knockdown of TWIST2 enables FN-RMS cells to exit the cell cycle and undergo myogenic differentiation, thereby reducing the growth of FN-RMS xenograft tumors. ChIP-seq analysis revealed that most TWIST2-mediated gene regulation occurs independent of changes in MYOD binding in FN-RMS cells. Instead, TWIST2 controls the deposition of H3K27 acetylation at distal enhancers by interacting with the chromatin remodelers, SMARCA4 and CHD3, to activate growth-related and repress myogenesis-related TWIST2 target genes. Our findings provide new insights into the role of TWIST2 in maintaining an undifferentiated and tumorigenic state of FN-RMS and highlight the clinical potential of reversing the TWIST2-regulated phenotype.
Project description:Sarcomas are derailed in pathways that specify mesenchymal lineages during embryogenesis, causing tumor cells to stall at early stages of differentiation. Among them, rhabdomyosarcoma (RMS) is a pediatric soft tissue sarcoma of skeletal muscle origin. A key feature of RMS is their inability to terminally differentiate despite the high expression of master myogenic regulator MYOD. The bHLH transcription factor TWIST2, which governs mesenchymal stem cell identity and restricts myogenesis, is overexpressed in patient fusion-negative RMS (FN-RMS) tumors. We show that knockdown of TWIST2 enables FN-RMS cells to exit the cell cycle and undergo myogenic differentiation, thereby reducing the growth of FN-RMS xenograft tumors. ChIP-seq analysis revealed that most TWIST2-mediated gene regulation occurs independent of changes in MYOD binding in FN-RMS cells. Instead, TWIST2 controls the deposition of H3K27 acetylation at distal enhancers by interacting with the chromatin remodelers, SMARCA4 and CHD3, to activate growth-related and repress myogenesis-related TWIST2 target genes. Our findings provide new insights into the role of TWIST2 in maintaining an undifferentiated and tumorigenic state of FN-RMS and highlight the clinical potential of reversing the TWIST2-regulated phenotype.
Project description:Integrated analysis of genome-wide ChIP-Seq and RNA-Seq data revealed the first dynamic chromatin and transcriptional landscape of Twist2 binding during myogenic differentiation. During differentiation, Twist2 competes with MyoD at shared DNA motifs to direct global gene transcription and repression of the myogenic program. Additionally, TWIST2 shapes the epigenetic landscape to drive chromatin opening at oncogenic loci and chromatin closing at myogenic loci. These epigenetic changes redirect MyoD binding from myogenic genes towards oncogenic, metabolic, and growth genes.
Project description:DBX1 is a transcriptional repressor whose role in human cancer is poorly understood. DBX1 is highly expressed in FN-RMS. Here, we depleted DBX1 expression with 2 shRNAs targeting DBX1 in a human FN-RMS cell line we derived from a PDX - SJRHB015721_X1. We determined the transcriptional changes using a Clariom S human microarray.
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:Rhabdomyosarcoma (RMS) is a pediatric mesenchymal-derived malignancy encompassing Fusion Positive (FP)-RMS expressing PAX3/7-FOXO1 and Fusion Negative (FN)-RMS often mutated in the RAS pathway. RMS expresses the master myogenic transcription factor MYOD that, paradoxically, is unable to support differentiation while essential for tumor cell survival. We identify here SKP2, an oncogenic E3-ubiquitin ligase, as a critical driver of tumorigenesis in FN-RMS. SKP2 is overexpressed in RMS at the highest levels among several adult and pediatric cancers and its expression is maintained by MYOD through an intronic enhancer within the gene. In FN-RMS SKP2 promotes cell cycle progression and prevents differentiation directly targeting p27Kip1 and p57Kip2, respectively, unlocking a transcriptional myogenic program, partly MYOD-dependent, resulting in de novo expression of terminal muscle differentiation markers. SKP2 depletion strongly affects stemness and tumorigenic features in vitro and prevents in vivo tumor growth. The in vitro effects are mirrored by the SKP2 inhibitor SMIP004. Moreover, the investigational NEDDylation inhibitor MLN4924 hampers SKP2 functions restraining FN-RMS cell survival and tumor growth. Our results uncover a MYOD-SKP2 axis crucial for the crosstalk between transcriptional and post-translational mechanisms that contribute to FN-RMS tumorigenesis and broaden the understanding of MYOD function. Furthermore, they suggest inhibition of NEDDylation as a potential therapeutic approach in this tumor.
Project description:Rhabdomyosarcoma (RMS) is a pediatric mesenchymal-derived malignancy encompassing Fusion Positive (FP)-RMS expressing PAX3/7-FOXO1 and Fusion Negative (FN)-RMS often mutated in the RAS pathway. RMS expresses the master myogenic transcription factor MYOD that, paradoxically, is unable to support differentiation while essential for tumor cell survival. We identify here SKP2, an oncogenic E3-ubiquitin ligase, as a critical driver of tumorigenesis in FN-RMS. SKP2 is overexpressed in RMS at the highest levels among several adult and pediatric cancers and its expression is maintained by MYOD through an intronic enhancer within the gene. In FN-RMS SKP2 promotes cell cycle progression and prevents differentiation directly targeting p27Kip1 and p57Kip2, respectively, unlocking a transcriptional myogenic program, partly MYOD-dependent, resulting in de novo expression of terminal muscle differentiation markers. SKP2 depletion strongly affects stemness and tumorigenic features in vitro and prevents in vivo tumor growth. The in vitro effects are mirrored by the SKP2 inhibitor SMIP004. Moreover, the investigational NEDDylation inhibitor MLN4924 hampers SKP2 functions restraining FN-RMS cell survival and tumor growth. Our results uncover a MYOD-SKP2 axis crucial for the crosstalk between transcriptional and post-translational mechanisms that contribute to FN-RMS tumorigenesis and broaden the understanding of MYOD function. Furthermore, they suggest inhibition of NEDDylation as a potential therapeutic approach in this tumor.
Project description:Rhabdomyosarcoma (RMS) is a pediatric mesenchymal-derived malignancy encompassing Fusion Positive (FP)-RMS expressing PAX3/7-FOXO1 and Fusion Negative (FN)-RMS often mutated in the RAS pathway. RMS expresses the master myogenic transcription factor MYOD that, paradoxically, is unable to support differentiation while essential for tumor cell survival. We identify here SKP2, an oncogenic E3-ubiquitin ligase, as a critical driver of tumorigenesis in FN-RMS. SKP2 is overexpressed in RMS at the highest levels among several adult and pediatric cancers and its expression is maintained by MYOD through an intronic enhancer within the gene. In FN-RMS SKP2 promotes cell cycle progression and prevents differentiation directly targeting p27Kip1 and p57Kip2, respectively, unlocking a transcriptional myogenic program, partly MYOD-dependent, resulting in de novo expression of terminal muscle differentiation markers. SKP2 depletion strongly affects stemness and tumorigenic features in vitro and prevents in vivo tumor growth. The in vitro effects are mirrored by the SKP2 inhibitor SMIP004. Moreover, the investigational NEDDylation inhibitor MLN4924 hampers SKP2 functions restraining FN-RMS cell survival and tumor growth. Our results uncover a MYOD-SKP2 axis crucial for the crosstalk between transcriptional and post-translational mechanisms that contribute to FN-RMS tumorigenesis and broaden the understanding of MYOD function. Furthermore, they suggest inhibition of NEDDylation as a potential therapeutic approach in this tumor.
Project description:Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children. Prognosis for patients with high grade and metastatic disease is still very poor, and survivors are burdened with long-lasting side effects. Therefore, more effective and less toxic therapies are needed. Surface proteins are ideal targets for antibody-based therapies, like bispecific antibodies, antibody drug conjugates, or chimeric antigen receptor (CAR) T cell. Specific surface targets for RMS are scarce. Here, we performed a surfaceome profiling based on differential centrifugation enrichment of surface/membrane proteins and detection by LC-MS on six fusion-positive (FP) RMS cell lines, five fusion-negative (FN) RMS cell lines, and three RMS patient-derived xenografts (PDXs). 699 proteins were detected in the three RMS groups. Ranking based on expression levels and comparison to expression in normal MRC-5 fibroblasts and myoblasts, followed by statistical analysis, highlighted known RMS targets such as FGFR4, NCAM1, and CD276/B7-H3, and revealed AGRL2, JAM3, MEGF10, GPC4, CADM2, as potential targets for immunotherapies of RMS. L1CAM expression was investigated in RMS tissues and strong L1CAM expression was observed in more than 80% of alveolar RMS tumors, making it a practicable target for antibody-based therapies of alveolar RMS.