【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.
Objective To research the expressions of miR-196b and HoxB8 mRNA in colorectal cancer and theircorrelation with clinicopathologic features，and to explore the relationship between miR-196b and HoxB8 in vivo. Methods Expressions of RNA （including miR-196b and HoxB8 mRNA） and HoxB8 protein were detected respectively by using quantitative real-time reverse transcriptase PCR and Western blot in 30 cases of colorectal cancer and corresponding normalmucous membrane tissues. Results In colorectal cancer tissues，expressions of miR-196b and HoxB8 mRNA were higher than those of the corresponding normal mucous membrane tissues （P＜0.05）. Expression of miR196b mRNA was assoc-iated with lymph node metastasis，neoplasm stages （Ⅰ＋ⅡandⅢ＋Ⅳ），and distant metastasis （P＜0.05），on the otherhand，no significant differences were observed regarding tumor site，size，gross type，depth of invasion，tissue differentiation，age，and sex （P＞0.05）. Expression of HoxB8 mRNA was no significant differences concerning lymph node metastasis，tumor stages （Ⅰ＋Ⅱ，Ⅲ＋Ⅳ），distant metastasis，tumor site，size，gross type，depth of invasion，tissue differentiation，age，and sex （P＞0.05）. The expression of miR-196b mRNA was negatively correlated with HoxB8 mRNA expression （r=-0.458，P＜0.05），and HoxB8 protein expression with no obvious correlation （r=-0.236，P＞0.05） in colorectal cancer tissues. Conclusions The expressions of miR-196b and HoxB8 mRNA in colorectal cancer tissues are higher，the high expression of miR-196b mRNA is related to the tumorigenesis and progression of colorectal cancer as well as correlated with prognosis in colorectal cancer. The miR-196b inhibits the expression of HoxB8 mRNA by binding to the3′-UTR of target HoxB8 mRNA.