Prox1 haploinsufficiency sensitizes the pancreas to KrasG12D-induced transformation

Oncogenic mutations in Kras initiate neoplastic transformation in the pancreas through a process that hijacks the activity of developmental regulators and induces an inflammatory microenvironment. We report that the homeodomain transcription factor Prox1 is a novel component of a progenitor signature that is activated in acinar cells undergoing dedifferentiation and ductal metaplasia conversion. Also, the conditional deletion of a single Prox1 allele markedly accelerates early transformation and significantly enhances features of inflammation in pancreatic tissues carrying a Kras oncogene. By using in vitro and in silico approaches, we demonstrate that Prox1 negatively regulates the expression of proinflammatory genes and genes implicated in malignant transformation in pancreatic cells. Microrrays were used to identify gene expression profiles and pathways that are differentially activated after enforced expression of PROX1 in the PROX1-negative human pancreatic ductal adenocarcinoma (PDAC) cell line Capan1. MSCV retroviral transduction was used to generate Capan1 cells that ectopically express PROX1 and selected for puromycin resistance. Three independent transductions with control virus (MSCV_puro) and 3 independent transductions with Prox1-cDNA virus (MSCV_PROX1_puro) were conducted for these experiments.