Prognostic Significance of Nuclear βCatenin Expression in Patients with Colorectal Cancer from Iran

Background: Beta catenin plays a key role in cancer tumorigenesis. However, its prognostic significance in patients with colorectal cancer (CRC) remains controversial. It has been demonstrated that 90% of all tumors have a mutation in individual components of multiple oncogenes in Wnt/β-catenin pathway. Accumulation of nuclear β-catenin in cytoplasm leads to uncontrolled cell proliferation. Thus, nuclear β-catenin accumulation may be a valuable biomarker associated with invasion, metastasis and poor prognosis of CRC. Objectives: In this study the prognostic value of beta catenin expression in 165 Iranian CRC patients was evaluated. Patients and Methods: In this cross sectional retrospective study immunohistochemistry analyses of formalin-fixed paraffin-embedded (FFPE) tumor tissues were performed to characterize the expression of nuclear β-catenin in a series of 165 Iranian patients with colorectal carcinoma. Heat-induced antigen retrieval using the microwave method was applied for all staining procedures. Staining was scored independently by two observers, and a high level of concordance (90%) was achieved. Statistical analysis was done using the SPSS software for Windows, version 13.0.0 (SPSS Inc., Chicago, IL). Two-tailed P 0.05 was considered statistically significant. Results: The patients consisted of 85 males and 80 females. Eighty-eight patients had primary tumor of the rectum and sigmoid, while 77 patients had primary tumor of the colon. The mean period of follow-up was 47.2 ± 10 months and the median period of follow-up was 38 months (range 6 - 58) for each patient. Of 165 tumors, 32 tumors (19.39 %) showed expression of β-catenin and 133 (80.6 %) were negative for β-catenin expression. Based on our findings the distribution of Microsatellite Instability (MSI) status differed between patients with nuclear β-catenin positive and negative tumors and this difference was significant (P = 0.001). Patients with nuclear β-catenin positive expression profile were found to be younger than patients with negative nuclear β-catenin expression (P = 0.010). Univariate and multivariate analysis showed that tumors with β-catenin expression had a poorer prognosis compared to tumors without β-catenin expression. Conclusions: According to our findings, the distribution of nuclear b-catenin expression is a poor prognostic marker in patients with colon cancer.