Hesperetin Induces Apoptosis Of Human Lung Carcinoma Cell PC9 Through Endoplasmic Reticulum(ER) Stress

Introduction and Aim: Most deaths caused by cancer are arisen from Lung carcinoma in China due to the difficultly diagnosis at early stage.About 70% of patients already developed progressed-disease at the time of diagnosis.Latinum-based compounds are widely used in the treatment of lung cancer;however,with severe side effects include nephrotoxicity,myelosuppression and gastrointestinal reactions.Therefore,it is very important to find new drugs for lung cancer therapy.Hesperetin is a kind of flavonoids extracted from citrus plants,which has numerous biological functions,especially cancer chemopreventive and anti-tumor effects.The chemoprevention of cancer is concerned about anti-inflammatory and antioxidant effects.Hesperetin also induces tumor cell apoptosis,inhibits tumor metastasis and angiogenesis by targeting multiple proteins simultaneously so as to effectively killing tumor cells.However,in lung cancer,the molecular mechanisms of hesperetin's anticancer effects are still need to research.Therefore,this study was conducted to observe the effect of Hesperetin on the proliferation and apoptosis of lung adenocarcinoma cell line PC9,and to explore the correlation between ER stress response induced by hesperetin and apoptosis of PC9 cells.Material and methods: LDH Cytotoxicity Assay Kit was used to monitor the cytotoxic effect of hesperetin on PC9 cells.Fluorescence-activated cell sorting(FACS)was utilized for determining the apoptosis of PC9 cells pretreated with different dosages of hesperetin.Proteins implicated in mitochondrial apoptosis and ER stress,including Caspase-3,Caspase-9,Apaf-1,Bcl-2,cytochrome C,CHOP,Caspase-4,Bip,p-JNK,p-Perk,IRE1 and ATF6 were measured by western-blotting.Results: 1)Cytotoxic effect of hesperetin on PC9 cells was conspicuously aggrandized with either the increase of hesperetin concentration or prolongation of incubation time.2)Apoptosis,especially early apoptosis among PC9 cells were intensified by the increasing doses of hesperetin.3)By hesperetin administration,Caspase-3,Caspase-9,Apaf-1 and cytochrome C were upregulated and Bcl-2 downregulated.4)Hesperetin also induced the expression of ER stress-related proteins or receptors,such as CHOP,Caspase-4,Bip,p-JNK,p-Perk,IRE1 and ATF6.Conclusions: Hesperetin exhibited cytotoxic and pro-apoptotic efficacies on PC9 cells,which may implicate ER stress.