The Mecchanism And Significance Of Sorafenib-induced Autophagy In HepG2Cells

Autophagy is a highly conserved metabolic process in cell. Recentresearches indicated that autophagy plays an important role in cancerinitiation, progression and treatment. But the role of autophagy in cancertherapy is contradictory. Therefore, researches on the mechanisms ofautophagy induction and its functions in cancer therapy have attractedmuch attention. Sorafenib, the first FDA approved targeted therapy for livercancer, has been shown to induce autophagy in liver cancer cells. Thismaybe result in the therapy-resistance of sorafenib in liver cancer. On thebasis of our previous data, we further explore the mechanisms ofsorafenib-induced autophagy and it’s role in sorafenib-treated HepG2cells.This work may provide experimental evidences and new insights forimprovement of the sorafenib therapy effect on liver cancer.Obsjective:To investigate significance and the mechanism of sorafenib-inducedautophagy in HepG2cell line.Methods:HepG2cells were transfected with GFP-LC3plasmid, and observedthe autophagosome formation under fluorosence microscopy after treatment with sorafenib. The interaction of Mcl-1and Beclin1were testedby co-immunoprecipitation (Co-IP) in HepG2cells. The anti-tumor effectof sorafenib was detected in presence of autophagy inhibitor chloroquine(CQ) or knockdown of autophagy-related gene Atg5by siRNA. Total celldeath was tested by trypan blue and Hoechst33258staining. The Changesof autophagic and apoptotic proteins Atg5, Beclin1, LC3, Mcl-1, P-ERKand PARP were detected by Western Blot.Results:（1）In HepG2cells, Sorafenib upregulated LC3-Ⅱ protein expressionin dose-dependent manner. HepG2cells transfected with GFP-LC3plasmid showed autophogosome-like dot fluorescence when treated withsorafenib.（2）Mcl-1protein level was downregulated while Beclin1remainedunchaged after treatment with sorafenib.（3）The interaction between Mcl-1and Beclin1were reduced bysorafenib treatment.（4）Finally，the anti-tumor effect of sorafenib was enhanced whenautophagy was inhibited.Conclusions:Sorafenib may induce autophagy by down-regulating Mcl-1expression and reducing the interaction between Mcl-1and Beclin1.Autophagy inhibition can enhance the antitumor effect of sorafenib.