Abstract 4126: Validation of hypoglycosylated MUC1-CIN85 protein-protein interaction as a new therapeutic target for prevention of cancer invasion and metastasis

Overexpression and abnormal glycosylation of the epithelial glycoprotein MUC1 in cancer cells promotes metastasis. We have identified CIN85 (Cbl-interacting protein 85 KDa), as a binding partner of MUC1 in tumors. MUC1/CIN85 complex is found in early as well as advanced clinical stages of breast, ovarian, colon and prostate cancers among others. Co-localization of MUC1 and CIN85 on invadopodia structures enhances invasion and migration of cancer cells. Our hypothesis is that preventing the formation or dissociating existing CIN85/MUC1 complexes may result in a less aggressive tumor by decreasing local invasion and preventing distant metastases. To test this hypothesis, we have already identified and tested two novel compounds that significantly reduce the association between hypoglycosylated form of MUC1 and CIN85, and at 10μM concentration drastically reduce the migratory activity of mouse and human epithelial cancer cells. Our preliminary data also suggest that dissociation of the MUC1 and CIN85 complex decreases expression of hypoglycosylated MUC1, restoring the expression of its normal, fully glycosylated form. We are currently investigating the MUC1/CIN85-dependent signaling pathway with a particular focus on the ability of CIN85 to modulate MUC1 glycosylation by controlling its plasma membrane-Golgi trafficking. Ongoing experiments in an in vivo mouse model will confirm the ability of these drug compounds to decrease tumor growth and metastasis and validate CIN85/MUC1 complex as a viable therapeutic target and support development and testing of more potent antagonists.

Citation Format: Sandra Cascio, Jacque Faylo, Raahul Sriram, Anda Vlad, Carlos Camacho, Olivera J. Finn. Validation of hypoglycosylated MUC1-CIN85 protein-protein interaction as a new therapeutic target for prevention of cancer invasion and metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4126. doi:10.1158/1538-7445.AM2017-4126

Abstract 4153: Abnormal expression of MUC1 mucin on colon epithelia stimulates production of pro-inflammatory cytokines promoting colitis-associated colon cancer in a murine model

MUC1 is a transmembrane glycoprotein aberrantly expressed in human adenocarcinoma as well as chronic inflammatory conditions. We have previously demonstrated that the tumor form of MUC1, in association with p65, upregulates the expression of pro-inflammatory cytokines in the tumor microenvironment, including IL-6 and TNF-alpha, by modulating their transcriptional activity in epithelial cancer cells. Here, we explored the mechanism underlying MUC1/p65-induced transcription of IL-6 and TNF-alpha in colon cancer cells and its significance for the microenviroment of colitis that is known to be the precursor to cancer. We used a mouse model of colitis-associated colon cancer where wild type (WT) and human MUC1 transgenic (MUC1.Tg) mice are given carcinogen azoxymethane (AOM), followed by three cycles of 1.2% dextran sodium sulfate (DSS) in drinking water to induce colitis. MUC1.Tg showed higher tumor incidence, decreased survival, increased body weight loss and shorter colon length. These features accelerated the severity of inflammation-induced colon cancer. Consistent with our previous in vitro data, expression of NF-kB family members was higher in MUC1.Tg mice compared to WT. We previously showed that in tumors, MUC1/p65 complex modulated the expression of histone methyltransferase Enhancer of Zeste protein-2 (EZH2) and interaction with pro-inflammatory cytokine promoters. In order to understand the significance of MUC1/p65-modulated cytokines in progressive colitis that gives rise to colon cancer, we analyzed infiltration of inflammatory cells into the inflamed colon tissues. The number of infiltrating macrophages was much higher in AOM/DSS-treated MUC1.Tg mice compared to WT. ELISA assay and gene expression analyses demonstrated that the treatment with AOM/DSS in the presence of human MUC1 on the colonic epithelia resulted in a significant increase in M1 type macrophage-associated genes, including IL-6, TNF-alpha and iNOS, whereas M2 type macrophage markers such as Arginase 1, Ym1, and IL-10 were drastically reduced when compared to colon tissues of treated WT mice. Taken together, our findings reveal a pro-inflammatory role for MUC1 in colitis-related carcinogenesis. Our study also provides a mechanism by which MUC1 accelerates tumor initiation and progression.

Citation Format: Sandra Cascio, Jacque Faylo, Jia Xue, Olivera Finn. Abnormal expression of MUC1 mucin on colon epithelia stimulates production of pro-inflammatory cytokines promoting colitis-associated colon cancer in a murine model. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4153.

MUC1 promotes an inflammatory microenvironment aggravating colitis-associated tumorigenesis in mice through up-regulation of pro-inflammatory cytokines

MUC1 is a transmembrane glycoprotein aberrantly expressed in human adenocarcinoma as well as chronic inflammatory conditions. We previously demonstrated that the tumor form of MUC1, in association with p65, upregulates expression of pro-inflammatory cytokines, including IL-6 and TNF-alpha, by modulating their transcription in epithelial cancer cells. Using azoxymethane/dextran sulfate sodium (AOM/DSS) murine model of inflammation driven colon carcinogenesis, we explored mechanism underlying MUC1/p65-induced transcription of IL-6 and TNF-alpha and its significance for the microenvironment of colitis-associated cancer. MUC1.Tg mice showed higher tumor incidence, decreased survival, greater body weight loss and shorter colon length. Consistent with our previous in vitro data, expression of NF-kB-dependent cytokines was higher in MUC1.Tg mice compared to WT. Moreover, we discovered that MUC1/p65 complex modulates IL-6 and TNF gene expression by regulating the crosstalk of post-translational modifications on their promoters. To understand the significance of MUC1/p65-modulated cytokines in progressive colitis that gives rise to colon cancer, we analyzed infiltration of inflammatory cells into the inflamed colon tissues. ELISA assay and gene expression analyses demonstrated that the treatment with AOM/DSS in the presence of human MUC1 on the colonic epithelia resulted in a significant upregulation of M1 type macrophage-associated genes, including IL-6, TNF-alpha and iNOS, whereas expression of M2 type macrophage markers, such as Arginase 1, Ym1 and IL-10, were drastically reduced compared to WT mice. Thus our findings reveal a pro-inflammatory role for MUC1 in colitis-related carcinogenesis.