Antiproliferative activity of melatonin by transcriptional inhibition of cyclin D1 expression: a molecular basis for melatonin-induced oncostatic effects.

Melatonin is endowed with a growth inhibitory effect in MCF-7 breast cancer cells whose mechanism has been related to an antiestrogenic activity exerted by inhibition of binding of the estradiol-estrogen receptor complex to its DNA responsive element. Looking for downstream gene determinants of this effect, we performed a transcriptome profiling by high-density microarrays of estrogen-treated MCF-7 cells exposed or not to melatonin. We found that cyclin D1 was one of the main downregulated genes by melatonin.