// Sandra Cascio 1, 2 , Jacque L. Faylo 3 , Joshua C. Sciurba 1 , Jia Xue 1 , Sarangarajan Ranganathan 4 , Jason J. Lohmueller 1 , Pamela L. Beatty 1 and Olivera J. Finn 1 1 Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA 2 Fondazione Ri.Med, Palermo, 90133, Italy 3 Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA 4 Division of Pediatric Pathology, Children's Hospital of Pittsburgh, Pittsburgh, PA 15224, USA Correspondence to: Sandra Cascio, email: firstname.lastname@example.org Keywords: colitis-associated cancer; Mucin 1; altered glycosylation; EzH2; pro-inflammatory cytokines Received: June 14, 2017 Accepted: September 08, 2017 Published: October 27, 2017 ABSTRACT The abnormal hypoglycosylated form of the epithelial mucin MUC1 is over-expressed in chronic inflammation and on human adenocarcinomas, suggesting its potential role in inflammation-driven tumorigenesis. The presence of human MUC1 aggravates colonic inflammation and increases tumor initiation and progression in an in vivo AOM/DSS mouse model of colitis-associated cancer (CAC). High expression levels of pro-inflammatory cytokines, including TNF-α and IL-6, were found in MUC1+ inflamed colon tissues. Exogenous TNF-α promoted the transcriptional activity of MUC1 as well as over-expression of its hypoglycosylated form in intestinal epithelial cells (IECs). In turn, hypoglycosylated MUC1 in IECs associated with p65 and up-regulated the expression of NF-κB-target genes encoding pro-inflammatory cytokines. Intestinal chronic inflammation also increased the expression of histone methyltransferase Enhancer of Zeste protein-2 (EzH2) and its interaction with cytokine promoters. Consequently, EzH2 was a positive regulator of MUC1 and p65-mediated IL-6 and TNF-α gene expression, and this function was not dependent on its canonical histone H3K27 methyltransferase activity. Our findings provide a mechanistic basis for already known tumorigenic role of the hypoglycosylated MUC1 in CAC, involving a transcriptional positive feedback loop of pro-inflammatory cytokines.