Mutant SF3B1 promotes malignancy in PDAC.

Simmler, Patrik; Ioannidi, Eleonora I; Mengis, Tamara; Marquart, Kim Fabiano; Asawa, Simran; Van-Lehmann, Kjong; Kahles, Andre; Thomas, Tinu et al. · Elife · 2023

basic_science · Level V

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Abstract

The splicing factor SF3B1 is recurrently mutated in various tumors, including pancreatic ductal adenocarcinoma (PDAC). The impact of the hotspot mutation SF3B1<sup>K700E</sup> on the PDAC pathogenesis, however, remains elusive. Here, we demonstrate that Sf3b1<sup>K700E</sup> alone is insufficient to induce malignant transformation of the murine pancreas, but that it increases aggressiveness of PDAC if it co-occurs with mutated KRAS and p53. We further show that Sf3b1<sup>K700E</sup> already plays a role during early stages of pancreatic tumor progression and reduces the expression of TGF-β1-responsive epithelial-mesenchymal transition (EMT) genes. Moreover, we found that SF3B1<sup>K700E</sup> confers resistance to TGF-β1-induced cell death in pancreatic organoids and cell lines, partly mediated through aberrant splicing of <i>Map3k7</i>. Overall, our findings demonstrate that SF3B1<sup>K700E</sup> acts as an oncogenic driver in PDAC, and suggest that it promotes the progression of early stage tumors by impeding the cellular response to tumor suppressive effects of TGF-β.

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