Study On The Cisplatin-resistant Reversal Effects Of Emetine In Human Hepatocellular Carcinoma HepG2/DDP Cells And Its Mechanism

BackgroundNatural products are a huge treasure house for the discovery of new drugs.Natural products and their derivatives play an increasingly important role in the development of new anticancer drugs because of their diverse structures,diverse biological activities,low toxic and side effects and wide sources.Emetine is an isoquinoline alkaloid from Rubiaceae plants.Many studies have found that oxyphylline can induce apoptosis of a variety of tumor cell lines in combination with chemotherapeutic drugs,but the specific mechanism is not clear.The in-depth study of its active mechanism can provide a new strategy for tumor treatment.ObjectiveThis study aims to investigate the reversal of cisplatin resistance of drug-resistant hepatoma cell line HepG2/DDP by emetine and its mechanism.MethodThe drug-resistant hepatoma cell line HepG2/DDP was established by high-dose cisplatin（DDP）shock combined with low-dose continuous induction.Reverse virtual screening,molecular docking,surface plasmon resonance（SPR）and western blot assays were employed to explore the target of emetine and its interaction with PARP-1.The target was validated by transfection assay in vivo.The inhibitory effect of emetine combined with DDP on the proliferation of HepG2/DDP cells was detected by cytotoxicity assay.The sensitization effect of emetine was verified by flow cytometry,and the expression of the apoptosis related proteins BCL2,Bax and Cleaved-caspase-3were analyzed by Western blot.ResultEmetine enhanced the sensitivity of HepG2/DDP cells to DDP and reduced the resistance index（RI）from 3.69 to 0.93.Reverse virtual screening,molecule docking,SPR results showed that emetine can stably bind to PARP-1.Western blot assays showed that emetine had a potent enzymatic inhibitory activity against PARP-1 in vivo.Furthermore,emetine’s potentiation of DDP in HEPG2/DDP cells nearly disappeared when the cells were transfected with si RNAs against PARP-1.Flow cytometry showed that emetine could enhance the proapoptotic effect of DDP on HepG2/DDP cells.ConclusionEmetine can enhance the sensitivity of HepG2/DDP cells to DDP,and its mechanism may be related to its inhibition of PARP-1.Therefore,we believed that emetine could be used to be a lead compound to for drug-resistant tumor treatment.