Biology subjects

Chudasama, P.

Publications and source records attributed to Chudasama, P..

4 recordsLinked to original sources

bioRxiv2026

EWSR1::ATF1 hyperactivation via TRIM11 depletion triggers lethal metabolic rewiring in clear cell sarcoma

Clear cell sarcoma (CCS) is an ultra-rare and aggressive soft tissue sarcoma driven by the EWSR1::ATF1 fusion oncoprotein. Currently, no effective and well-tolerated treatment options are available to CCS patients. Direct inhibition of fusion transcription factors is precluded by the absence of defined ligand-binding pockets, whereas their abundance is under the control of the ubiquitin-proteasome system (UPS), offering an alternative avenue for biology-guided treatment. Here we show the abundance of EWSR1::ATF1 is tightly regulated by the UPS, and that release of this constraint is lethal to CCS cells. A reporter-based CRISPR/Cas9 knockout screen of UPS components identified TRIM11 as an E3 ligase that regulates turnover of EWSR1::ATF1, which it recognises as a neosubstrate without altering wild-type EWSR1 or ATF1. Depletion of TRIM11 increased nuclear fusion protein abundance, amplified the fusion-driven transcriptional programs and reduced viability. Proteomic analysis identified the cataplerotic enzyme phosphoenolpyruvate carboxykinase 1 (PCK1), a direct EWSR1::ATF1 target, as the key mediator of lethal effects of fusion hyperactivation. Extracellular flux analysis, isotope tracing and quantitative metabolomics revealed excessive cataplerotic carbon withdrawal and impaired oxidative phosphorylation as the underlying mechanism. In patient tumors, high PCK1 expression associated with metastatic transcriptome programs and disease presentation, as well as shorter survival. Taken together, we report that hyperactivation of EWSR1::ATF1 opens a metabolic vulnerability, establishing TRIM11 as an actionable dependency and PCK1 as a candidate prognostic biomarker in CCS.

cancer biology↗

bioRxiv2026

Alternative lengthening of telomeres stratifies complex karyotype sarcomas into distinct genomic and transcriptomic states

Complex karyotype sarcomas (CKS) are heterogeneous mesenchymal malignancies that typically lack recurrent actionable oncogenic drivers and remain therapeutically challenging. Loss of ATRX is a recurrent feature of CKS and defines a particularly high-risk subgroup. ATRX loss is also associated with activation of the alternative lengthening of telomeres (ALT) pathway, and ALT-positive sarcomas have been linked to poor clinical outcomes. However, the molecular underpinnings underlying ALT-status-dependent differences in CKS, as well as the therapeutic vulnerabilities associated with ALT, remain poorly defined. By integrating C-circle-based ALT detection across 776 sarcoma samples with multi-modal sequencing of five CKS subtypes, we find that ALT activity is associated with enriched hallmarks of genomic instability. ALT-positive transcriptomes are dominated by a coordinated DNA damage response and mitotic program, in contrast to oncogenic signaling pathways that drive TERT activation in ALT-negative tumors. Long-read sequencing reveals telomere repeat clusters and telomere-mediated healing at structural breakpoints in ALT-positive tumors. These events also occur on extrachromosomal DNA (ecDNA), linking ALT activity to ecDNA biology. Together, our findings position ALT status as an important stratifying feature of CKS and identify ALT-associated transcriptional programs as potential therapeutic targets.

cancer biology↗

bioRxiv2024

Somatic gene delivery for flexible in vivo modeling of high-risk sarcoma

A particular challenge hampering therapeutic advancements for high-risk sarcoma patients is the broad spectrum of molecularly distinct sarcoma entities and the corresponding lack of suitable model systems to recapitulate and study these diseases. To overcome this predicament, we developed a novel genetically-controlled, yet versatile mouse modeling platform allowing delivery of different genetic lesions by electroporation (EPO) of the thigh muscle wildtype mice. This optimized sarcoma EPO-GEMM (EPO-based genetically engineered mouse model) platform allowed the generation of ten biologically distinct sarcoma entities, including Synovial Sarcoma (SS), fusion-positive and fusion-negative Rhabdomyosarcoma (RMS), Alveolar Soft Part Sarcoma (ASPS), Undifferentiated Pleomorphic Sarcoma (UPS) and Infantile Fibrosarcoma (IFS). Comprehensive molecular profiling and cross-species analyses confirmed faithful recapitulation of the human disease, including the expression of relevant immunotherapy targets. Syngeneic allografting enabled reliable preservation and scalability of Sarcoma-EPO-GEMMs for treatment trials, such as B7-H3-directed CAR-T cell therapy in an immunocompetent background.

cancer biology↗

bioRxiv2022

Heterogeneity in the gene regulatory landscape of leiomyosarcoma.

Soft-tissue sarcomas are group of rare, tremendously heterogeneous, and highly aggressive malignancies. Characterizing inter-tumor heterogeneity is crucial for selecting suitable sarcoma therapy, as the presence of diverse molecular subgroups of patients can be associated with disease outcome or response to treatment. While cancer subtypes are often characterized by differences in gene expression, the mechanisms that drive these differences are generally unknown. We therefore set out to model the regulatory mechanisms driving sarcoma heterogeneity. We subtyped soft-tissue sarcomas based on patient-specific, genome-wide gene regulatory networks and found pronounced regulatory heterogeneity in leiomyosarcoma--one of the most common soft-tissue sarcomas subtypes that arises in smooth muscle tissue. To characterize this regulatory heterogeneity, we developed a new computational framework. This method, PORCUPINE, combines knowledge on biological pathways with permutation-based network analysis to identify pathways that exhibit significant regulatory heterogeneity across a patient population. We applied PORCUPINE to patient-specific leiomyosarcoma networks modeled on data from The Cancer Genome Atlas and validated our results in an independent dataset from the German Cancer Research Center. PORCUPINE identified 37 heterogeneously regulated pathways, including pathways that represent potential targets for treatment of subgroups of leiomyosarcoma patients, such as FGFR and CTLA4 inhibitory signaling. We validated the detected regulatory heterogeneity through analysis of networks and chromatin states in leiomyosarcoma cell lines. In addition, we showed that the heterogeneity identified with PORCUPINE is not associated with methylation profiles or clinical features, thereby suggesting an independent mechanism of patient heterogeneity driven by the complex landscape of gene regulatory interactions.

bioinformatics↗