Bone Morphogenetic Protein (BMP) signaling upregulates expression of the E protein repressors, ID1 and ID3, in pancreatitis and pancreatic ductal adenocarcinoma

Identification of biological modulators of pancreatic ductal adenocarcinoma (PDAC) initiation and progression is of critical importance as it remains one of the deadliest cancers. We have previously shown that ID1 and ID3 are highly expressed in human PDAC and function to repress expression of E47 target genes involved in acinar cell differentiation and quiescence. Here, mining of large bulk RNA-seq and single cell RNA-seq (scRNA-seq) datasets has associated high expression of ID1 and ID3 with poor PDAC patient survival. We show that upregulated expression of ID1 and ID3 in human PDAC cells occurs in response to canonical BMP signaling through pSMAD1/5/9. Conversely, treatment with Noggin, an endogenous BMP antagonist, or with DMH1 and LDN193189, small molecule inhibitors of BMP receptors, reduced expression of ID1, ID3 and cell cycle control genes. Based on our RNA-seq and immunohistochemical analyses, upregulation of BMP signaling to ID1 and ID3 is an early event that occurs in human pancreatic intraepithelial neoplasia (PanIN) and murine models of pre-neoplastic lesions induced by mutant Kras. Strikingly, the same result was observed in a murine model of pancreatitis induced by the cholecystokinin (CCK) analog caerulein. Moreover, we show that caerulein is sufficient to induce BMP signaling and expression of ID1 and ID3 in a cell-autonomous manner in non-transformed rodent exocrine pancreas cells. Together, the data suggest that canonical BMP signaling upregulates expression of ID1 and ID3 early in pancreas pathogenesis and that pancreatic cancer cells remain addicted to this important signaling circuit as the disease progresses. Future exploration of druggable targets within this pathway could be of therapeutic benefit in the treatment of pancreatitis and PDAC.