THE INHIBITORY EFFECT OF MELATONIN ON THE GROWTH OF HUMAN BLADDER CARCINOMA T24 CELL LINE

Objective: To study the inhibitory effects of melatonin and its inhibitory mechanism on the growth of human bladder carcinoma T24. Methods: The inhibitory effects of melatonin with various concentrations on the human bladder carcinoma T24 lines in vitro were determined by MTT assay. The mechanism of the inhibition was observed by flow cytometry (FCM) and transmission electron microscopy (TEM). Results: The 30% inhibition concentration (IC 30) value was 0.71 mmol · L -1 and the 50% inhibition concentration (IC 50) value was 1.20 mmol · L -1. The population doubling time of T24 cells treated with melatonin at 0.71 mmol · L -1 was 43.2 hours, which was significant different from that of 34.6 hours of the control group. Using FCM, we found that the cell percentage increased during the G 1 phase, but decreased during the S stage. The degenerated ultra-structure of the cell treated with melatonin was also observed by TEM. Conclusion: The results suggest that melatonin can inhibit the growth of human bladder carcinoma T24. The inhibitory effects of melatonin might be the prolonging of the staging from G 1 to S in the cell cycle.