藤黄酸调节肺腺癌A549细胞甾体类受体共激活因子3表达的意义

Effects of gambogic acid on the regulation of steroid receptor coactivator-3 in A549 cells

目的观察藤黄酸对人肺腺癌细胞株A549增殖和凋亡的影响，及其对甾体类受体共激活因子3（SRC-3）表达的调控作用。方法以不同浓度的藤黄酸处理人肺腺癌A549细胞，采用四甲基偶氮唑蓝（MTT）法检测细胞的增殖活性，Hoechst 33258染色法分析细胞凋亡的改变，共聚焦显微镜观察A549细胞中SRC-3蛋白的分布情况，Western blot和逆转录聚合酶链反应（RT-PCR）法检测藤黄酸对A549细胞中SRC-3 mRNA和蛋白表达的影响。结果藤黄酸能明显抑制A549细胞的增殖，其抑制作用呈时间和浓度依赖性，24和48h的半数抑制浓度（IC90）分别为（3．17±0．13）μmol／L和（1．85±0．08）μmol／L。藤黄酸能使A549细胞出现典型的细胞凋亡形态改变。空白对照组的A549细胞中，SRC-3 mRNA和蛋白均呈高表达，且主要分布于细胞核；经藤黄酸处理后，A549细胞中SRC-3 mRNA和蛋白的表达水平均明显下降。结论藤黄酸能明显抑制人肺腺癌细胞A549的增殖，并可能通过下调SRC-3 mRNA和蛋白的表达量而诱导A549细胞产生凋亡。藤黄酸有望成为治疗肺癌的新型靶点药物。

Objective To investigate the effects of gambogic acid （GA） on the proliferation inhibition and apoptosis induction in Human lung adenocarcinoma A549 cells in vitro, as well as the regulation of steroid receptor coactivator-3 （SRC-3） to explore the relationship between them. Methods The effect of GA on the growth of A549 ceils was studied by MTT assay. Apoptosis was detected by Hoechst 33258 staining. The localization of SRC-3 was determined by confocal laser scanning microscopy. Western blot and RT-PCR technique were applied to assess the expression of SRC-3. Results GA presented a striking proliferation inhibition potency on A549 cells in vitro, as well as apoptosis induction activity in a time- and dose-dependent manner. The IC50 value for 24 h was （3.17±0.13）μmol/L. Overexpression of SRC-3 was found in A549 ceils, whereas the SRC-3 protein and mRNA expression levels were significantly downregnlated in A549 ceils induced by GA in a dose-dependent manner. The location of SRC-3 was situated mainly in the cell nuclei. Conclusion GA exhibits a potent proliferation inhibition and apoptosis induction in human lung adenocarcinoma A549 cells ,which might correspond to the downregulation of the expression of SRC-3. Thus, it promises to be a new target drug for lung cancer treatment.