Inhibitors of Apoptosis Proteins Expression and Their Prognostic Significance in Colorectal Carcinoma

Background: The expression of the inhibitor of apoptosis proteins (IAPs) family has not been fully investigated in colorectal carcinomas. This study investigated IAP expression in colorectal carcinomas and assessed their prognostic significance. Methods: Livin, XIAP, and SMAC/DIABLO expression was assessed by immunohistochemistry in 159 colorectal carcinomas. Correlations between protein expression and clinicopathological features were evaluated. The survival data analysis was estimated according to the Kaplan-Meier method. Result: Increased expression of IAPs in cancer tissues compared to surrounding nonneoplastic counterparts was observed in 67 cases (42.1%) for Livin, 50 cases (31.4%) for XIAP, and 68 cases (42.8%) for SMAC. A significant correlation was found between Livin expression and tumor differentiation, and SMAC expression and tumor location. The recurrence-free and overall survival of patients with low Livin expression were inferior to those of patients with high Livin expression (p=0.054 and 0.095, respectively). High XIAP expression was significantly associated with shorter progression-free survival (p=0.041). Conclusions: Our study demonstrated that altered expression of IAP family members, including Livin, XIAP, and SMAC, is frequent in colorectal carcinoma. This result suggests that high Livin expression and low XIAP expression may be a favorable prognostic implication related to patient survival.