Objective: Agomelatine is an antidepressant drug which recently started to be used in our country. Agomelatine is described as a potent agonist of melatonin receptor, which has an important physiological role especially in the regulation of human circadian rhythms. This study was conducted to investigate the effects of melatonin and agomelatine on human ovarian (A2780) and prostate (PC-3) cancer cell viability.

Materials and Methods: A2780 and PC-3 cell lines were used in the study. The 0.1 mM, 1 mM, 5 mM ve 10 mM concentrations of melatonin and agomelatine were administered to all cell lines for 24 h. Changes in cell viability were determined by the MTT (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) assay. The 50% inhibitory concentration (LogIC50) was calculated according to MTT assay results.

Results: It was determined that all concentrations (0.1 mM, 1 mM, 5 mM ve 10 mM) of melatonin and agomelatine administered to human cancer cells (A2780 and PC-3) for 24 h reduced % cell viability (P<0.05).

Conclusion: The results of this study demonstrate that melatonin and agomelatine have strong cytotoxic and antitumor effects against human prostate and ovarian cancer cell lines.