Pancreatic cancers with aberrant expression of macrophage migration inhibitory factor (MIF) are particularly aggressive. To identify key signaling pathways that drive disease aggressiveness in tumors with high MIF expression, we analyzed the expression of coding and non-coding genes in high and low MIF-expressing tumors in multiple cohorts of pancreatic ductal adenocarcinoma (PDAC) patients. The key genes and pathways identified were linked to patient survival and were mechanistically, functionally and clinically characterized using cell lines, a genetically engineered mouse model and PDAC patient cohorts. Here we report evidence of a novel MIF-driven signaling pathway that inhibits the orphan nuclear receptor NR3C2, a previously undescribed tumor suppressor that impacts aggressiveness and survival in PDAC. Mechanistically, MIF upregulated miR-301b which targeted NR3C2 and suppressed its expression. PDAC tumors expressing high levels of MIF displayed elevated levels of miR-301b and reduced levels of NR3C2. Additionally, reduced levels of NR3C2 expression correlated with poorer survival in multiple independent cohorts of PDAC patients. Functional analysis showed that NR3C2 inhibited epithelial-to-mesenchymal transition and enhanced sensitivity to the gemcitabine, a chemotherapeutic drug used in PDAC standard of care. Furthermore, genetic deletion of MIF disrupted a MIF-mir-301b-NR3C2 signaling axis, reducing metastasis and prolonging survival in a genetically engineered mouse model of PDAC. Taken together, our results offer a preclinical proof-of-principle for candidate therapies to target a newly described MIF-miR-301b-NR3C2 signaling axis for PDAC management.

Free radical-induced cellular stress contributes to cancer during chronic inflammation. Here, we investigated mechanisms of p53 activation by the free radical, NO. NO from donor drugs induced both ataxia-telangiectasia mutated (ATM)-and ataxiatelangiectasia mutated and Rad3-related-dependent p53 posttranslational modifications, leading to an increase in p53 transcriptional targets and a G2͞M cell cycle checkpoint. Such modifications were also identified in cells cocultured with NO-releasing macrophages. In noncancerous colon tissues from patients with ulcerative colitis (a cancer-prone chronic inflammatory disease), inducible NO synthase protein levels were positively correlated with p53 serine 15 phosphorylation levels. Immunostaining of HDM-2 and p21 WAF1 was consistent with transcriptionally active p53. Our study highlights a pivotal role of NO in the induction of cellular stress and the activation of a p53 response pathway during chronic inflammation.posttranslational modification ͉ phosphorylation