The Effect And Mechanisms Of Celastrol On Apoptosis Of Osteosarcoma HOS Cells

Purpose:This study is to mainly explore the effect of celastrol on HOS cells line of human osteosarcoma and the related mechanisms(especially Endoplasmic reticulum stress(ERS),mitochondrial pathway and autophagy).We further explored the effect of PERK signaling on ERS and its relationship with apoptosis and autophagy.Methods:HOS was subjected to celastrol and the proliferation of HOS cells was detected by CCK-8 assay.The cell morphology was observed by inverted phase contrast microscopy,and the apoptotic morphology was detected by fluorescence microscopy after Hoechst33258 staining.The apoptotic rate and Ca2+ concentration were analyzed by flow cytometry.Transmission electron microscope was used to observe cell ultrastructure.The expression of p-PERK was measured by immunofluorescent staining The protein expression was test by Western blotting.Results:The results showed that various concentrations of celastrol could inhibit the proliferation of HOS cells in a dose-dependent manner.The celastrol has the capability to induce the apoptosis of HOS cells and ERS pathway and mitochondrial pathway were involved in apoptosis induced by celastrol in HOS cells.Pretreatment with the inhibitor of PERK signaling pathway GSK2656157 could promote apoptosis.Conclusion:ERS pathway,mitochondrial related pathway and autophagy were involved in the apoptosis of the HOS cells induced by celastrol.The ERS pathway not only protected HOS cells from apoptosis but also mediated apoptosis.Further research had found that the expression of p-PERK increased,while ERS was induced,which contributed to the resistance of celastrol.These results will enrich our understanding of the mechanisms mediating celastrol-induced tumor cells death and the relationships among ERS,autophagy and apoptosis.Further researches are required to focus on how to regulate the relationships of ERS,apoptosis and autophagy to enhance anti-osteosarcoma effect of celastrol.