– Melatonin has been described to possess cell protecting activity in normal cells but was shown to induce apoptotic cell death in cancer cells. It potentiates apoptosis induced by the flavonoid flavone significantly. A combination of flavone and melatonin increased caspase-3-like activity 30-fold and 80% of cells exhibited fragmentation of DNA when compared to untreated controls. Melatonin caused an increase in cytosolic lactate levels that most likely allows the flavone-induced activation of the mitochondrial pyruvate/lactate importer to deliver more substrates to mitochondrial respiration.
– Melatonin is a hormone identified in plants and pineal glands of mammals and possesses diverse physiological functions. Fisetin is a bio-flavonoid widely found in plants and exerts antitumor activity in several types of human cancers. However, the combinational effect of melatonin and fisetin on antitumor activity, especially in melanoma treatment, remains unclear. Here, we tested the hypothesis that melatonin could enhance the antitumor activity of fisetin in melanoma cells and identified the underlying molecular mechanisms. The combinational treatment of melanoma cells with fisetin and melatonin significantly enhanced the inhibitions of cell viability, cell migration and clone formation, and the induction of apoptosis when compared with the treatment of fisetin alone. Moreover, such enhancement of antitumor effect by melatonin was found to be mediated through the modulation of the multiply signaling pathways in melanoma cells.