Objective      To investigate the effect of pyropheophorbide-a methyl ester-mediated photodynamic therapy (MPPa-PDT) on the autophagy of human bone giant cell tumor cell line SGC-0404 and the relationship between autophagy and apoptosis.       Methods      After SGC-0404 cells were treated with MPPa-PDT

cell apoptosis was analyzed by Hochest33258 nuclear staining

and the level of reactive oxygen species (ROS) was detected by dichlorofluorescin diacetate (DCFH-DA) staining. Cell autophagy was observed by monodansylcadaverine (MDC) staining and electron microscopy. The expression of LC3-Ⅱ/LC3-Ⅰ and Beclin-1 was assayed by Western blotting. Meanwhile

cell apoptosis was detected by flow cytometry.       Results      After SGC-0404 cells were treated with MPPa-PDT

nuclear condensation

fragmentation and other typical apoptotic morphological changes were observed

and the level of ROS in the MPPa-PDT group was 21.07 times

18.68 times

and 19.66 times higher than that in the control group

the MPPa group

and the LED group

respectively (P0.05). MDC staining and electron microscopy results showed that MPPa-PDT resulted in formation of typical autophagosome. Western blotting indicated that LC3-Ⅱ/LC3-Ⅰ and Beclin-1 expression in the MPPa-PDT group was higher than those in the other 3 groups (P0.05).After autography was inhibited with 3-methyladenine

the cell apoptosis rate was remarkably increased (27.69±2.23 vs 43.17±2.87

P0.05).       Conclusion      MPPa-PDT can induce cell apoptosis and autophagy in SGC-0404 cells. And at the early stage of MPPa-PDT treatment

autophagy can delay apoptosis

thus exerting protective effect against apoptosis.