Brg1 promotes both tumor suppressive and oncogenic activities at distinct stages of Pancreatic cancer formation

Pancreatic Ductal Adenocarcinoma (PDA) develops predominantly through pancreatic intraepithelial neoplasia (PanIN) and intraductal papillary mucinous neoplasm (IPMN) precursor lesions. Pancreatic acinar cells are reprogrammed to a “ductal like” state during PanIN-PDA formation. Here, we demonstrate a parallel mechanism operative in mature duct cells where they undergo “ductal retrogression” to form IPMN-PDA. Brg1, a catalytic subunit of the SWI/SNF complexes, plays a critical antagonistic role in IPMN-PDA development. In mature duct cells Brg1 inhibits the dedifferentiation that precedes neoplastic transformation, thus attenuating tumor initiation. In contrast, Brg1 promotes tumorigenesis in full-blown PDA by supporting a mesenchymal-like transcriptional landscape. We have exploited this duality of Brg1 functions to develop a novel therapeutic approach using an epigenetic drug JQ1. In summary, this study demonstrates the context-dependent roles of Brg1 and points to potential therapeutic treatment options based on epigenetic regulation in PDA. Overall design: Duct cells were isolated from mice of 3 different genotypes and duct cells from 3 mice of each genotype were sequenced. For the put back experiments, control retrovirus and that expressing Brg1 were transdcued in Brg1 null IPMN mouse cell line.

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Roy N, Malik S, Villanueva KE, Urano A, Lu X, Von Figura G, Seeley ES, Dawson DW, Collisson EA, Hebrok M