ABSTRACT
Objective To investigate the potential mechanism that melatonin at higher concentrations inhibits the proliferation of human MG-63 osteosarcoma cells,so as to provide a certain experimental basis for the better application of melatonin in the treatment of diseases in Department of Orthopedics. Methods MG-63 cells cultured in vitro were treated with melatonin at a concentration of 4 mmol/L . Western blotting and real-time PCR method were used to analyze the effect of melatonin on the expression of cyclins and CDKs at protein and mRNA levels ,respectively. Results Western blotting and real-time PCR analyses showed that melatonin's inhibitory effect was possibly through the downregulation of cyclin D1 and CDK4 that related to the G1 phase,and downregulation of cyclin B1 and CDK1 that related to the G2/M phase. However,there was no obvious dif-ference of cyclin E,CDK2,and cyclin A,which were related to G1/S transition and S phase. Conclusion Melatonin may significantly inhibit hu-man osteosarcoma cell proliferation by inducing cell cycle arrest in a time-dependent manner,which is related to the downregulation of cyclin D1, CDK4,cyclin B1 and CDK1.