Photodynamic Effect of HMME on Cell Line U-2OS and its Mechanism Analysis

Objective: To evaluate the effect of HMME-mediated photodynamic therapy on human osteosarcoma cell line U-2OS,and to investigate the therapy-related apoptosis mechanism of U-2OS cell in vitro.Methods: Different laser doses(0,3,6,9 J·cm-2) were applied to irradiate the human U-2OS cell after the osteosarcoma cell had been treated with different concentrations of HMME(0,10,20,30,40 μg·ml-1) for 4 hours.MTT was employed to detect the cell survival to yield the EC50 dosage in the study group,control group,drug control group and laser control group.The EC50 corresponding HMME dosage and laser dose were identified as the standard for the study group.The apoptotic morphology of the study group was observed under optical microscopy after processed with Hoechst33342 nuclear staining method,compared with a blank control group.Western blot was applied to analyzed the expression of caspase-7,caspase-9 and PARP-1 protein.Results: U-2OS cell survival rate detected MTT ranged from 96.7 % to 100 %,EC50 for HMME were 40.1 μg·ml-1(6 J·cm-2)and 25.0 μg·ml-1(9 J·cm-2).Western blot of caspase-7,caspase-9 and PARP-1 protein indicated a significant difference between study group and the control group.Conclusion: Human osteosarcoma cell line U-2OS cell can be treated with HMME-mediated photodynamic therapy by inducing the activation of caspase pathway in vitro.