14-3-3sigma expression is an independent prognostic parameter for poor survival in colorectal carcinoma patients

14-3-3sigma is an intracellular, dimeric, phosphoserine binding protein that is expressed in epithelial cells and involved in cancer development. In this study, we examined the expression of 14-3-3sigma and evaluated its clinical significance in colorectal carcinoma.

Expression of 14-3-3sigma was analyzed by Western blot in nine colorectal carcinoma cell lines, eight paired colorectal carcinoma tissues, and normal mucosas. Immunohistochemistry was used to evaluate expression of 14-3-3sigma in tissues of 121 colorectal carcinoma patients and to correlate it with clinical parameters.

Western blot analysis of colorectal carcinoma cell lines and tissues revealed strong 14-3-3sigma expression in four of eight cell lines and 14-3-3sigma overexpression in carcinomas compared with normal mucosa in six of eight colorectal carcinoma tissue pairs. Immunohistochemical analysis revealed 14-3-3sigma overexpression in 38.8% of colorectal carcinoma samples. Furthermore, highly positive immunoreactivity was significantly correlated with tumor differentiation (P < 0.001) and pT stage (P < 0.003). In Kaplan-Meier analysis, 14-3-3sigma overexpression was associated with a significantly decreased survival time compared with negatively stained or low stained cases (P < 0.0096). In multivariate regression analysis, 14-3-3sigma expression emerged as a significant independent parameter (P < 0.037).

These results provide evidence that 14-3-3sigma expression increases during carcinoma progression in a subset of colorectal carcinoma. The overexpression of this antigen identifies patients at high risk. It is tempting to suggest that 14-3-3sigma overexpression either promotes tumor proliferation and/or prevents apoptotic signal transduction in colorectal carcinoma. Thus, targeting 14-3-3sigma might be a new therapeutic strategy in colorectal carcinoma.