HIF-1α regulates malignant biological behavior and epithelial interstitial transformation of hepatocellular carcinoma through PD-L1 in hypoxia microenvironment
Objective To investigate the mechanism of HIF-1α regulating hepatocellular carcinoma(HCC)cell proliferation,migra-tion,invasion and epithelial mesenchymal transformation through programmed death ligand 1(PD-L1)in hypoxia microenvironment.Methods Fifty-seven patients diagnosed with liver cancer and treated at the Yancheng Clinical College of Xuzhou Medical University from September 2016 and September 2018 were selected as the study objects.The expression of HIF-1α and PD-L1 were detected by immunohistochemistry,and the relationship between HIF-1α,PD-L1 and clinicopathological and overall survival was statistically ana-lyzed.The hypoxia model of HCC was established by Cobalt Chloride(CoCl2),and the survival rate of HCC under different concentra-tions of CoCl2 was detected by Cell Counting Kit-8(CCK-8)method.The changes of migration and invasion ability of hypoxic cells and parental cells were detected by scratch test and transwell invasion test.The expressions of HIF-1α and PD-L1 in hypoxic cells and pa-rental cells were detected by Western blot.Small interfering RNA(siRNA)targeting HIF-1α and PD-L1 plasmid were designed to trans-fect HCC cells with liposome into hypoxic cells.The changes of cell migration and invasion ability before and after transfection were de-tected by scratch assay and Transwell(migration/invasion)invasion assay.The expression levels of HIF-1α,PD-L1 and Epithelial mes-enchymal transformation(EMT)-related proteins before and after transfection were detected by Western blotting.Results HIF-1α and PD-L1 were highly expressed in HCC tissues compared with paracancellular tissues(P<0.05).There were significant differences in tu-mor size,tumor differentiation degree and China liver cancer staging(CNLC)stage between high and low PD-L1 expression groups(P<0.05).There were significant differences in tumor number,AFP expression level,and CNLC stage between high and low PD-L1 expres-sion groups(P<0.05).Kaplan-Meier analysis showed that the survival rate of patients in HIF-1α and PD-L1 high expression groups was significantly lower than that in low expression group(P<0.05).Compared with normoxic cells,the number of cells penetrating the com-partment was significantly increased by hypoxic cells[(429.33±12.01)vs.(244.3±8.14),t=-22.08,P<0.001].The proliferation,migra-tion and invasion ability of CoCl2 anoxic HCC cells were enhanced,and the expression levels of HIF-1α and PD-L1 were significantly increased(P<0.05).Compared with parental cells,the proliferation,migration and invasion ability of hypoxic HCC cells were signifi-cantly decreased after HIF-1α siRNA treatment(P<0.05),and the expressions of PD-L1,Vimentin and Twist1 were significantly de-creased,while the expressions of E-cadherin were significantly increased(P<0.05).After co-transfection of HIF-1α siRNA and PD-L1 plasmid,the changes of HIF-1α siRNA-mediated invasion,migration ability and EMT-related indexes could be reversed.Conclusion HIF-1α and PD-L1 are highly expressed in liver cancer.Liver cancer patients with high HIF-1α and PD-L1 expression have poor prog-nosis.In hypoxia microenvironment,HIF-1α can regulate malignant biological behavior and epithelial interstitial transformation pro-cess through PD-L1 in HCC cells.
Carcinoma,hepatocellularHypoxia microenvironmentHypoxia-inducible factor-1α(HIF-1α)Programmed death ligand 1(PD-L1)Epithelial-mesenchymal transformation(EMT)
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