Myc instructs and maintains pancreatic adenocarcinoma phenotype

Pancreatic ductal adenocarcinoma (PDAC) is characterized by its dismal prognosis and its signature fibroinflammatory phenotype. We show that activation of Myc in PanIn epithelial cells is alone sufficient to instruct and maintain immediate transition of indolent PanIN to PDACs phenotypically identical to the spontaneous human disease. Myc does this by inducing a distinct, tissue-specific ensemble of instructive signals that, together, coordinate changes in multiple, stromal and inflammatory cell types to generate the signature PDAC stroma. We also demonstrate that the Myc PDAC switch is completely reversible and that Myc deactivation immediately triggers meticulous disassembly of both PDAC tumor and stroma. Hence, both the formation and deconstruction of the complex PDAC phenotype may be mediated by a single, reversible molecular switch.