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Biology subjects

Roy, S. F.

Publications and source records attributed to Roy, S. F..

2 recordsLinked to original sources

Spatial multi-omics resolve epithelium-fibroblast gradients and highlight NESTIN-NOTCH1-expressing subepithelial fibroblasts during human pancreatic tumorigenesis

Intraductal papillary mucinous neoplasms (IPMNs) are cystic precursors of pancreatic ductal adenocarcinoma undergoing dynamic epithelial and stromal remodeling during progression. In this study, we integrated computational pathology, cyclic immunofluorescence, and Xenium spatial transcriptomics to define the spatial organization of the IPMN microenvironment. We queried cell-based histopathological features and identified stromal patterns strongly associated with epithelium proximity. Cyclic immunofluorescence and Xenium revealed a subepithelial gradient extending from myofibroblasts to inflammatory fibroblasts. Xenium further identified a distinct subepithelial NOTCH1-NESTIN-expressing fibroblast subset in myofibroblasts that expands with tumor progression. By recapitulating the spatial remodeling event using human pancreatic tumor cells and primary myofibroblast co-culture models, we demonstrated the capacity of pancreatic tumor cells to induce a NESTIN-expressing state in neighboring myofibroblasts. These findings reveal new dynamic epithelial-stromal interactions through subepithelial NESTIN+ fibroblasts associated with pancreatic tumorigenesis and immediate microenvironment remodeling by active tumor cells, highlighting the power of computational pathology integrated with spatial transcriptomics.

cancer biology↗

ERK Activation by BRAFV600E suppresses mesenchymal migration and tumorigenesis by inhibiting RAC1.

BRAFV600E mutation occurs in 46% of melanomas and drives high levels of ERK activity and ERK-dependent proliferation. However, BRAFV600E is insufficient to drive melanoma in GEMM models, and 82% of human benign nevi harbor BRAFV600E mutations. We show here that BRAFV600E inhibits mesenchymal migration by causing feedback inhibition of RAC1 activity. ERK pathway inhibition induces RAC1 activation and restores migration and invasion. In cells with BRAFV600E, mutant RAC1, overexpression of PREX1, PREX2, or PTEN inactivation restore RAC1 activity and cell motility. Together, these lesions occur in 48% of BRAFV600E melanomas. Thus, although BRAFV600E activation of ERK deregulates cell proliferation, it prevents full malignant transformation by causing feedback inhibition of cell migration. Secondary mutations are, therefore, required for tumorigenesis. One mechanism underlying tumor evolution may be the selection of lesions that rescue the deleterious effects of oncogenic drivers. Statement of significanceBRAFV600E activation of ERK causes feedback inhibition of cell migration and invasion and thus blocks tumorigenesis. Secondary genetic lesions are required to rescue these processes and enable tumor development. Thus, oncogenic feedback can shape the details of tumor progression and, in doing so, selects for new mutations that may be therapeutic targets.

cancer biology↗