Expression of the MT1 melatonin receptor in ovarian cancer cells.

Ovarian cancer (OC) is the leading cause of death among women with genital tract disorders. Melatonin exhibits oncostatic properties which it may effect through binding to its membrane receptor, MT1. The aim of this study was to determine the expression of MT1 in OC cells and to correlate this with clinical and pathological data. Immunohistochemistry was performed on 84 cases of OC. Normal ovarian epithelial (IOSE 364) and OC (SK-OV-3, OVCAR-3) cell lines were used to examine the MT1 expression at protein level using the western blot and immunofluorescence technique. The expression of MT1 was observed as cytoplasmic-membrane (MT1(CM)) and membrane (MT1(M)) reactions. A positive correlation between MT1(CM) and MT1(M) was found in all the studied cases. There were no significant differences between the expression of MT1(CM), MT1(M), and histological type, staging, grading, presence of residual disease, or overall survival time. Immunofluorescence showed both MT1(M) and MT1(CM) expression in all the tested cell lines. Western blot illustrated the highest protein level of MT1 in IOSE 364 and the lowest in the OVCAR-3. The results indicate the limited prognostic significance of MT1 in OC cells.