目的:探讨乙型肝炎病毒X蛋白(hepatitis B virus X protein,HBx)参与人肝癌细胞hsp90α基因表达的调控机制。方法:采用半定量RT-PCR、蛋白质印迹法及荧光素酶活性检测技术,检测不同剂量HBx表达载体转染的HepG2细胞中hsp90α基因mRNA和蛋白表达及启动子活性的变化,并观察转录因子c-Myc阻断剂10058-F4对上述效应的影响。采用启动子实验分析c-Myc对hsp90α基因启动子的激活作用。RT-PCR和蛋白质印迹法检测表达HBx的HepG2细胞中c-Myc mRNA和蛋白表达情况;蛋白质印迹法及ELISA分析细胞外信号调节激酶1/2(ERK1/2)和磷酸化ERK1/2(p-ERK1/2)表达水平及内源性ERK的活性。结果:HBx基因转染HepG2细胞中hsp90α基因的mRNA和蛋白表达水平以及启动子活性呈剂量-依赖性增强,P=0.006 1;c-Myc阻断剂抑制了HBx对hsp90α基因表达的上调效应。c-Myc通过与c-Myc位点(-1094/-1088)结合转录激活hsp90α基因启动子活性。HBx使HepG2细胞中c-Myc mRNA和蛋白表达增强,并伴有ERK1/2蛋白磷酸化水平增加,ERK活性明显提高,P=0.032。结论:HBx通过ERK信号通路反式激活肝癌细胞c-Myc介导的hsp90α基因启动子活性,从而上调hsp90α基因表达。
Objective To study the chemical constituents from Millettia speciosa. Methods The compounds were isolated and purified by silica gel, Sephadex LH-20, ODS column chromatography, and recrystallization. The structures were identified using physicochemical and spectral data. Results Thirteen compounds were isolated from M. speciosa and identified as docosanoic acid （1）, tetracosane （2）, octadecane （3）, hexacosanoic acid （4）, β-sitosteroi acetate （5）, β-sitosterol （6）, syringin （7）, maackiain （8）, formononetin （9）, ψ-baptigenin （10）, rotundic acid （11）, pedunculoside （12）, and daucosterol （13）. Conclusion Compounds 5, 7, and 10-12 are obtained from this plant for the first time.
