【Abstract】Objective To investigate whether SUMO-1 enhances the apoptosis induced by wild-type p53 plasmid transfection in HepG2 cells. Methods The HepG2 cells were transfected respectively or simultaneouly with the following expressional plasmids as pcDNA3-wtp53（pwtp53，including human wild-type p53 gene），pCMV-HDM1B（pMDM2，including HDM2 gene， homologous gene as murine double minute gene 2），pcDNA3-His6-SUMO-1（pSUMO-1 ，including small ubiquitin-like modifier1 gene）and plasmid pcDNA3.The proteins expressed in cells were detected by means of Western blotting and the apoptosis rates of cells were measured by flow cytometry. Results The protein bands of p53 and MDM2 could be seen in cells transfected with pwtp53 and pMDM2. Meanwhile，the relative larger molecular weight bands were also seen in cells transfected with pSUMO-1 which represented the p53 and MDM2 protein modification by SUMO-1. Merely the trace of p53 protein was detected in cells not transfected with any plasmid or only transfected with empty plasmid and pSUMO-1. In cells transfected with pwtp53 and pwtp53+pSUMO-1，the apoptosis rates were (16.79±1.62)%and (18.15±1.36)%. When transfected with pwtp53+pMDM2，the rate decreased to (5.17±1.23)%. The apoptosis rate would come up again to (14.06±1.84)% after transfected with pwtp53+pMDM2+pSUMO-1 and the difference of rates were significant compared to the cells transfected with pwtp53+pMDM2 (PH＜0.01）. The apoptosis rates in other cells were less than 2% and had no significant difference. Conclusion SUMO-1 could increase the apoptosis induced by wild-type p53 plasmid transfection in HepG2 cells through combining to p53 protein or its post-translational modification and inhibiting p53 degradation by MDM2.
【Abstract】Objective To investigate the change of vascular endothelial growth factor (VEGF) expression in HepG2 cells under hypoxia. Methods HepG2 cells were cultured under hypoxia（hypoxia group） and normal condition (control group). VEGF expression of HepG2 cells was examined by immunohistochemical staining. The growth of HepG2 cells was examined by MTT colorimetry and cell count. VEGF level in the culture medium was measured by ELISA.Results After 48 h and 72 h of culture, the growth rate of HepG2 cells in hypoxia group was lower than that in control group (P＜0.05). The cell count in hypoxia group (2.51×104/μl and 2.69×104/μl, respectively) was much lower than that in control group(3.01×104/μl and 3.52×104/μl) after 48h and 72h of culture (P＜0.05). In hypoxia group, VEGF level in the culture medium after 24 h and 48 h was higher than that in control group (P＜0.05, P＜0.01). Conclusion Hypoxia may enhance the VEGF expression in HepG2 cells and this could be the reason of high expression of VEGF after transcatheterized hepatic arterial chemoembolization.