Abstract 587: Loss of colonic claudin-3 expression characterize colon cancer patients and predicts poor patient survival

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA The loss of cell-cell adhesion plays important role in promoting epithelial transformation and malignant cancer phenotype. In this regard, expression of claudin-3, a tight junction-integral protein, is reported to increase in prostate and ovarian cancers which contrast the paradigm. Notably, claudin-3 is highly expressed in the colon however its role in the regulation of colonic epithelial homeostasis or colon cancer remains unclear. In current studies, we have confirmed that claudin-3 is the most abundant claudin family member in the colon, and is present throughout the colonic crypt though it is more concentrated at the crypt top among the terminally differentiated colonocytes. We further found that in spontaneously differentiating Caco-2 cells, claudin-3 expression is markedly increased in terminally differentiated cells and correlates negatively with Vimentin and Smooth muscle actin (SMA) expressions. Dedifferentiation of the epithelial cells underlies colon carcinogenesis. In accordance, in a panel of 14 colon cancer cell lines, claudin-3 expression was either undetectable or low in 10 cell lines. In further analysis, using microarray data from a cohort of 268 {colorectal carcinoma (250) and normal (10)} colon cancer (CRC) specimens combined from the Vanderbilt Medical Center and the Moffitt Cancer Center, we found that claudin-3 expression level is significantly decreased in both colorectal adenoma (p<0.05) and carcinoma (p<0.001) versus normal mucosa. Further, IHC analysis of a colon cancer tissue microarray {TMA; colon tumors (67) and normal (10)} showed 23% of the tumors to be claudin-3 negative. In tumors, when claudin-3 was expressed, it was localized primarily in the cytoplasm compared to the surface expression in normal mucosa and its expression decreased with the increase in tumor grade. Overall, we observed a negative intensity score for claudin-3 with higher tumor grade. Further, based on the median expression levels, we found a significant and positive correlation of the greater levels of claudin-3 expression with patient survival (disease specific, disease free or overall survival; p<0.0008). We found a similar and significant suppression of claudin-3 expression in colon tumors induced in mice either spontaneously (by inactivation of the APC gene; APCmin mice) or pharmacological means [Azoxymethane (AOM) and Dextran sodium sulfate (DSS) administration). Notably, claudin-3 negative tumors retained E-cadherin expression suggesting that claudin-3 loss may be a rather sensitive marker for neoplastic colonic epithelial cells. Taken together, our data support strong correlation between claudin-3 expression, colonic epithelial differentiation and patient survival and highlights the tissue-specific regulation of claudin-3 and its efficacy as a potential colorectal tumor marker. Citation Format: Rizwan Ahmad, Zhimin Chen, Jian Wang, xi chen, Robert D. Beauchamp, Mary Kay Washington, Punita Dhawan, Amar B. Singh. Loss of colonic claudin-3 expression characterize colon cancer patients and predicts poor patient survival. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 587. doi:10.1158/1538-7445.AM2014-587