Activating mutations in Kras are nearly ubiquitous in human pancreatic cancer and initiate precancerous pancreatic intraepithelial neoplasia (PanINs) when induced in mouse acinar cells. PanINs normally take months to form but are accelerated by deletion of acinar cell differentiation factors such as Ptf1a, suggesting that loss of cell identity is rate limiting for pancreatic tumor initiation. Using a genetic mouse model that allows for independent control of oncogenic Kras and Ptf1a expression, we demonstrate that sustained Ptf1a is sufficient to prevent Kras-driven tumorigenesis, even in the presence of tumor-promoting inflammation. Furthermore, reintroducing Ptf1a into established PanINs reverts them to quiescent acinar cells in vivo. Similarly, Ptf1a re-expression in human pancreatic cancer cells inhibits their growth and colony-forming ability. Our results suggest that reactivation of an endogenous differentiation program can prevent and reverse oncogene-driven transformation in cells harboring tumor-driving mutations, introducing a potential paradigm for solid tumor prevention and treatment.
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