Mismatch repair,p53 and beta-catenin proteins in colorectal cancer

BACKGROUND: Mismatch repair (MMR) proteins (MSH2 and MLH1) deficiency is responsible for microsatellite instability (MSI) status. We evaluated p53 and beta-catenin expressions in colorectal cancer specimens with known microsatellite status, previously assessed by means of the polymerase chain reaction (PCR). We also analyzed the MMR proteins immunostaining and compared the results with those ascertained by PCR. MATERIALS AND METHODS: Twenty-five colorectal cancer patients were analyzed for immunohistochemical expression of p53, beta-catenin, MSH2 and MLH1 proteins. RESULTS: The microsatellite status was only significantly correlated with p53 expression and MRR proteins pattern. CONCLUSION: We demonstrated a significantly higher p53 expression in MSI colorectal specimens. The concordance rate between immunohistochemistry and PCR was so high (80%) that the immunohistochemical technique can be proposed as a method to select MSI patients for improved outcome and response to chemotherapy.