Analysis of the DNA mismatch repair proteins expression in malignant melanomas.

The importance of properly functioning DNA mismatch repair has been shown in several tumour types both hereditary and sporadic, but not yet in malignant melanomas. The aim of this study was to examine the expression of DNA mismatch repair genes (MLH1, MSH2, PMS1 and PMS2) in primary melanomas and to define their possible prognostic impact in 106 primary melanomas. MLH1 was found in 64 and MSH2 in 61 out of 106 melanomas. PMS1 and PMS2 proteins were present in 69 and 67 tumours, respectively. Loss of the expression of DNA mismatch repair proteins correlated with the increase of Clark levels. Cox regression analysis demonstrated some prognostic significance for PMS1 (forward p = 0.0018 and backward selections p = 0.0277), MLH1 (only forward selection p = 0.0081) and MSH2 (only backward selection p = 0.0115).