Cucurbitacin E induces apoptosis and attenuates activation of hepatic stellate cells via PI3K/Akt-AMPK-mTOR signaling pathway

OBJECTIVE Hepatic fibrosis is a wound-healing response for injury.Activated hepatic stellate cells(HSCs)are the preferred targets of anti-hepatic fibrotic therapies.cucurbitacin E(CuE)is,one well-known natural compound derived from traditional Chinese medicine,used in Asian countries for the prevention and treatment of hepatic disease.Therefore,the present study elucidated the mechanism of CuE on inducing apoptosis and attenuating hepatic fibrosis towards activated HSCs.METHODS The murine HSC(tHSC/Cl-6)cell line were incubated in 96-well plates and treated with TNF-αand CuE at various concentrations and indicated times.Cell viability was assessed with MTT assay.Another,t-HSC/Cl-6 were incubated in 6-well plates and also treated with TNF-α,CuE,AICAR or metformin for the indicated time and concentration.Cell protein and mRNA were prepared using kit and relevant signaling were detected by Western blotting and RT-PCR.RESULTS CuE inhibited cell proliferation of activated HSC/T-6cells in concentration-and time-dependent manner.CuE triggered the activation of caspase-3,cleaved the PARP,ration of bcl-2/bax,and cytochrom c protein in a time-and concentration-dependent manner.CuE decreased p-Erk/MAPK without effects on p-p38 and p-JNK.CuE inhibited the protein and mRNA expressions ofα-SMA,TIMP-1 and collagenⅠ in activated HSC-T6.CuE broadly blocked p-PI3 K,p-Akt,p-mTOR and p-p70S6 Kexpressions.CuE significantly increased phosphorylated AMPK expression as well as AICAR and metoformin.And metformin showed significantly higher activation of AMPK than AICAR.Ability of CuE on activation of AMPK was between AICAR and metformin.It′s also found that CuE significantly decreased p-mTOR as well as AICAR and metformin.CONCLUSION CuE could modulate HSC survival and activation as a potential anti-fibrotic agent for liver fibrosis treatment.The findings demonstrate that CuE induced HSC apoptosis via ERK/MAPK and PI3K/Akt-AMPK-mTOR signaling.