Background: Loss of DNA mismatch repair may result in resistance to platinum- based anticancer drugs. The hMLH1 and hMSH2 proteins play a critical role in the maintenance of genome integrity and are involved in resistance to platinum-based therapy in colorectal cancer, which is deficient in hMLH1 protein and endometrial cancer, as well as in hMSH2 protein. However, the predictive value of MLH1 and MSH2 expression in ovarian cancer cisplatin-resistance is still to be determined.
Objective: The aim of this study was to investigate the expression of hMLH1 and hMSH2 proteins in ovarian carcinoma specimens and to evaluate their prognostic significance by means of overall survival (OS) and progression-free survival rates (PSF).
Material: Ovarian cancer tissues were obtained from 61 patients: 45 platinum-sensitive and 16 platinum-resistant. hMLH1 and hMSH2 proteins expression was evaluated by immunohistochemistry, with the use of mouse monoclonal antibodies clone 14 for hMLH1 and clone FE11 for hMSH2. The log-rank test and Kaplan-Meier statistics were used to analyze the relationship between proteins expression and progression free survival, as well as the overall survival.
Result: No significant correlation was found between hMLH1 and hMSH2 expression and overall survival and progression free survival in the group of patients sensitive and resistant to cisplatin. No significant difference was found in proteins expression intensity between the two compared groups of patients. Age of patients, type of cancer histology, FIGO staging, grading, clinical response and CA 125 did not reveal correlation with the expression of the analyzed proteins.
Conclusion: The immunohistochemical expression of hMLH1 and hMSH2 proteins in ovarian cancer has no predictive value in resistance to cisplatin.