Background and purpose:Previous studies have suggested Na+-Ca2+ exchanger isoform 1 (NCX1) as a key component of calcium homeostasis was involved in the tumorigenesis. However, the role of NCX1 and calcium signal in tumorigenesis of hepatocellular carcinoma (HCC) has not been explored. This study aimed to investigate the effect of NCX1 on cell proliferation and migration of HCC HepG2 cells in vitro and the possible mechanism.Methods:Both the real-time fluorescent quantitative polymerase chain reaction (RTFQ-PCR) and Western blot were applied to assess the expression of NCX1 mRNA and protein in normal hepatic cells (LO2), HCC cell line (HepG2), human normal hepatic tissues and hepatocellular carcinoma tissues. The change of intracellular calcium signal in LO2 and HepG2 cells via acti-vated NCX1 channel in the presence or absence of Na+ was examined by a confocal laser scanning microscope. The effects of NCX1 special inhibitor KB-R7943 on cell proliferation and migration of HepG2 cells were measured by MTT and cellscratch test.Results:Both mRNA and protein expression of NCX1 were higher in HCC tissues and cell line HepG2 than in the normal tissues and cell line LO2 (P<0.05). The activation of NCX1 channel induced a slight rise in cytoplasmic Ca2+concentration ([Ca2+]cyt) in normal cells, but caused a marked increase in cancer cells. And the NCX1 activation induced intracellular calcium increase was significantly reversed by NCX1 inhibitor KB-R7943 (P<0.05). Both NCX1-mediated proliferation and migration of HepG2 were also significantly attenuated by the KB-R7943 (P<0.05).Conclusion:NCX1 is up-regulated in HCC cells and tissues. The activation of NCX1 mediates intracellular calcium homeostasis. The inhibition of NCX1 activity can suppress the proliferation and migration of HepG2 cells. It is suggested that NCX1 may be involved in the development and progression of HCC.

Objective:To discuss the effect of the small ubiquitin-like modifier-specific protease 1(SENP-1)/hypoxia-inducible factor 1α(HIF-1α)pathway on chronic intermittent hypoxia(CIH)-induced vascular endothelial injury in the rats,and to clarify the related mechanism.Methods:The SD rats were randomly divided into control group and CIH group,and then the rats in each group were further divided into 2,4,and 6-week subgroups,and there were 8 rats in each subgroup.The rats in CIH group were exposed to CIH in a CIH chamber to induce CIH and create the obstructive sleep apnea hypopnea syndrome(OSAHS)models,while the rats in control group were exposed to normoxic conditions.The serum and thoracic aorta tissue of the rats in various groups were collected at each time point.HE staining was used to observe the thoracic aorta vascular injury of the rats in various groups;ELISA method was used to detect the levels of nitric oxide(NO),endothelin-1(ET-1),von Willebrand factor(vWF),and thrombomodulin(TM)in serum of the rats in various groups;Western blotting method was used to detect the expression levels of SENP-1,HIF-1α,and vascular endothelial growth factor A(VEGFA)proteins in thoracic aorta tissue of the rats in various groups.In vitro,the aortic endothelial cells(rAECs)of the rats were cultured and infected with SENP-1 shRNA adenovirus(sh-SENP-1)to construct the cell line with low expression of SENP-1.The CIH was used to induce the vascular endothelial cell injury,and the cells were divided into CIH group,CIH+sh-NC group,and CIH+sh-SENP-1 group;control group was set up separately.CCK-8 method was used to detect the proliferation activities of the cells in various groups;ELISA method was used to detect the activities of lactate dehydrogenase(LDH)in the supernatant and the levels of NO,ET-1,malondialdehyde(MDA),and activities of superoxide dismutase(SOD)in the cells in various groups;flow cytometry was used to detect the apoptotic rates of the cells in various groups;Western blotting method was used to detect the expression levels of SENP-1,HIF-1α,and VEGFA proteins in the cells in various groups.Results:With the extension of CIH induction time,compared with control group,the thoracic aorta endothelium in CIH group gradually became rough and significantly thickened,the level of serum NO of the rats in CIH group was decreased(P＜0.05),and the levels of serum ET-1,vWF,and TM,and the expression levels of SENP-1,HIF-1α,and VEGFA proteins in thoracic aorta tissue were increased(P＜0.05).Compared with control group,the proliferation activity of the cells in CIH group was decreased(P＜0.05),the LDH activity in the supernatant,the levels of ET-1,MDA,and the apoptotic rate in the cells were increased(P＜0.05),while the levels of NO and activity of SOD in the cells were decreased(P＜0.05),and the expression levels of SENP-1,HIF-1α,and VEGFA proteins in the cells were increased(P＜0.05).Compared with CIH group,the proliferation activity of cells in CIH+sh-SENP-1 group was increased(P＜0.05),the activity of LDH in the supernatant,the levels of ET-1,MDA,and the apoptotic rate of the cells were decreased(P＜0.05),while the level of NO and activity of SOD in the cells were increased(P＜0.05),and the expression levels of SENP-1,HIF-1α,and VEGFA proteins were decreased(P＜0.05).Conclusion:The SENP-1/HIF-1α pathway is highly activated in the thoracic aorta injury tissue of the rats induced by CIH.Silencing SENP-1 expression can reduce CIH-induced vascular endothelial cell injury,and its mechanism may be related to downregulating the activation level of SENP-1/HIF-1α pathway.