ID1 mediates escape from TGF-β tumor suppression in pancreatic cancer

Abstract

TGF-β is an important tumor suppressor in pancreatic ductal adenocarcinoma (PDA), yet inactivation of TGF-β pathway components occurs in only half of PDA cases. TGF-β cooperates with oncogenic RAS signaling to trigger epithelial-mesenchymal transition (EMT) in pre-malignant pancreatic epithelial progenitors, which is coupled to apoptosis owing to an imbalance of SOX4 and KLF5 transcription factors. We report that PDAs that develop with the TGF-β pathway intact avert this apoptotic effect via Inhibitor of Differentiation 1 (ID1). ID1 family members are expressed in PDA progenitor cells and are components of a set of core transcriptional regulators shared by PDAs. PDA progression selects against TGF-β-mediated repression of ID1. The sustained expression of ID1 uncouples EMT from apoptosis in PDA progenitors. AKT signaling and mechanisms linked to low-frequency genetic events converge on ID1 to preserve its expression in PDA. Our results identify ID1 as a crucial node and potential therapeutic target in PDA.