Biology subjects

Somaiah, N.

Publications and source records attributed to Somaiah, N..

4 recordsLinked to original sources

bioRxiv2026

Spatially-Resolved Multiomic Atlas of Leiomyosarcoma Identifies Two Clinically Relevant Epigenetically-Driven Cell States

Leiomyosarcoma is a smooth muscle-derived malignancy marked by significant clinical heterogeneity. The extent and nature of cellular heterogeneity and molecular underpinnings remain poorly understood. To address this at transcriptomic and epigenomic levels, we performed single-nucleus multiome sequencing on untreated primary leiomyosarcoma tissues. Malignant cells segregated almost exclusively into two previously unrecognized and epigenetically distinct states: a dedifferentiated, mesenchymal-like subtype (MES) and a differentiated smooth muscle-enriched subtype (SMC). Chromatin accessibility profiling revealed strong enrichment of nuclear factor I (NFI) transcription factor motifs in MES cells, whereas AP-1 family motifs--most prominently FOSL2--were selectively accessible in SMC cells. Established leiomyosarcoma cell lines faithfully recapitulated these subtypes, and targeted depletion of NFI or AP-1 factors suppressed proliferation, invasion, and in vivo tumor growth, demonstrating functional dependency on these transcriptional programs. Spatial transcriptomics across 328 tissue cores from 128 leiomyosarcomas showed that immunosuppressive macrophages preferentially cluster around MES regions, revealing a subtype-specific tumor-immune niche. Clinically, MES-dominant tumors were associated with significantly worse patient outcomes. Through an epigenetic inhibitor screen, we identify and validate SMARCA4/2 inhibition as a promising therapeutic vulnerability for MES leiomyosarcomas. Together, this work defines two epigenetically driven, transcription factor-regulated, and clinically relevant states of leiomyosarcoma, revealing mechanistic underpinnings of tumor heterogeneity and uncovering actionable therapeutic strategies. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=93 HEIGHT=200 SRC="FIGDIR/small/726988v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@132928eorg.highwire.dtl.DTLVardef@133e3b7org.highwire.dtl.DTLVardef@1ab4398org.highwire.dtl.DTLVardef@e2de25_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2026

Spatially-resolved single cell atlas of liposarcoma reveals lineage hierarchies, immune niches, and regulatory circuits

Well-differentiated and dedifferentiated liposarcoma (WDLPS and DDLPS) exhibit markedly different clinical behaviors, with DDLPS showing greater aggressiveness, higher recurrence and metastasis rates, and worse outcomes. Using single-nucleus multiome sequencing, epigenomic profiling, and spatial transcriptomics, we characterized cellular and epigenetic heterogeneity between these subtypes at single-cell and spatial resolution. We found distinct phenotypic states reflecting altered lineage differentiation and plasticity: DDLPS is dominated by early-differentiated progenitor-like cells, sclerotic WDLPS displays broader mesenchymal lineage plasticity, and adipocytic WDLPS contains abundant committed adipocytes. The DDLPS immune microenvironment was dominated by immunosuppressive macrophages, whereas WDLPS harbored more T cells and inflammatory macrophages. Notably, sclerotic WDLPS displayed intermediate cellular and molecular features, suggesting it may represent a distinct WDLPS subtype. Importantly, we identified novel gene regulatory circuits underlying each state, including FABP4/PPARG programs in adipocytic WDLPS, GLI2/TCF7L2/RBPJ/KLF7 programs in sclerotic WDLPS, and KLF7/FOSL2/SP3/GLI2/RBPJ programs in DDLPS. H3K27ac-marked enhancers were enriched near adipocytic marker genes in WDLPS and mesenchymal markers in DDLPS. Together, these findings reveal the cellular heterogeneity of tumor and immune compartments across liposarcoma subtypes and identify regulatory programs driving their differentiation states. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=155 SRC="FIGDIR/small/713651v1_ufig1.gif" ALT="Figure 1"> View larger version (73K): org.highwire.dtl.DTLVardef@1c84ee1org.highwire.dtl.DTLVardef@1b2ad42org.highwire.dtl.DTLVardef@18ce5a6org.highwire.dtl.DTLVardef@138f615_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2025

ATRX Loss Predicts Poor Outcomes and Reveals a Therapeutic Vulnerability to TEAD Inhibition in Soft Tissue Sarcomas

ATRX is one of the most frequently altered genes in sarcoma and encodes an ATP-dependent chromatin remodeler implicated in maintaining heterochromatin. However, ATRX alterations have not been leveraged for sarcoma treatment. We observed loss of ATRX protein in 14% of soft tissue leiomyosarcoma (STLMS, n =127), 53% of uterine leiomyosarcoma (ULMS, n = 95), 37% of undifferentiated pleomorphic sarcoma (UPS, n = 82), and 8% of dedifferentiated liposarcoma (DDLPS, n = 84). ATRX loss was associated with significantly worse outcomes in ULMS, UPS, and DDLPS. ATRX knockout in sarcoma cells increased proliferation in cooperation with TP53 deletion. ATRX knockout led to chromatin de-repression and enrichment of PRDM4 and NFIX transcription factor (TF) motifs. PRDM4 and NFIX knockdown in ATRX-mutant sarcoma lines resulted in reduced proliferation and invasion suggesting epistatic relationship. Consistent with the known functional relationship between PRMD4 and YAP1, we observed that ATRX/TP53 KO cells were more sensitive to the TEAD inhibitor VT103 compared to TP53 KO and ATRX WT controls. Overall, our results identify ATRX loss as a prognostic factor of worse outcomes, implicate the ATRX-PRDM4-YAP1 axis as a novel underlying mechanism, and suggest use of TEAD inhibition as a potential therapeutic strategy for ATRX-deficient sarcomas. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=45 SRC="FIGDIR/small/689992v1_ufig1.gif" ALT="Figure 1"> View larger version (13K): org.highwire.dtl.DTLVardef@a759ecorg.highwire.dtl.DTLVardef@100c580org.highwire.dtl.DTLVardef@1a675c9org.highwire.dtl.DTLVardef@17f1f91_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2025

Rapid expansion of podoplanin-positive fibroblasts following radiation limits the anti-tumour CD8+ T-cell response to radiotherapy.

Radiotherapy is known to cause changes in the tumour stroma which can undermine treatment efficacy. Our understanding of this process has historically centred around effects driven by Transforming Growth Factor-beta (TGF-{beta}) and alpha-smooth muscle actin (-SMA)+ fibroblasts. Here, we identified a rapid expansion of podoplanin (PDPN)+ fibroblasts following radiotherapy in breast, head and neck and melanoma tumours. This fibrosis was not dependent on TGF-{beta}, but was downstream of a radiotherapy-induced adaptive immune response. CD8+ T-cells entering the tumour after radiation were sequestered at the interface between residual tumour cells and PDPN+ fibroblasts and failed to enter the tumour core. Genetic deletion of PDPN in fibroblasts impacted their cytoskeleton and ability to organise extracellular matrix. This was associated with increased CD8+ T-cell entry and spontaneous tumour regression. Overall, we identify a mechanism whereby PDPN+ fibrosis limits immune-mediated radiation cell kill and demonstrate that disruption of PDPN signalling favours tumour control. SignificanceIn this study we show that rapid podoplanin (PDPN)+ fibroblast expansion following radiotherapy limits immune-mediated radiation cell kill. Targeting PDPN and associated downstream signalling improves tumour control and is a promising strategy in combination with radiotherapy. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=175 SRC="FIGDIR/small/680949v1_ufig1.gif" ALT="Figure 1"> View larger version (61K): org.highwire.dtl.DTLVardef@1711bb0org.highwire.dtl.DTLVardef@d0c3a1org.highwire.dtl.DTLVardef@1db88adorg.highwire.dtl.DTLVardef@1ea3ab6_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗