藤黄酸增强人胃癌SGC7901/DDP细胞对顺铂的敏感性

目的 探讨藤黄酸（GA）对人胃癌SGC7901/DDP细胞顺铂敏感性的影响及其分子机制。方法 采用顺铂（DDP）浓度梯度递增法构建人胃癌顺铂耐药株SGC7901/DDP细胞，采用细胞计数盒-8（CCK-8）法检测藤黄酸和顺铂对SGC7901/DDP细胞的毒性作用，采用Chou-Talalay中效分析法定量评价藤黄酸和顺铂的联合作用效果，采用流式细胞术检测细胞凋亡，采用Western blotting方法检测Bcl-2、Bax、Survivin、多药耐药相关蛋白2（MRP2）、磷酸化氨基末端蛋白激酶（p-JNK）（Thr183/Tyr185）和JNK的蛋白水平。结果 藤黄酸与顺铂各自单独作用48 h的IC₅₀分别为2.94 μmmol/L和39.76 μmmol/L；当抑制率超过20%时，两者联合应用呈协同效应；藤黄酸可协同增强顺铂诱导的细胞凋亡（P<0.05），下调Survivin和MRP2蛋白水平（P<0.05），上调Bax蛋白水平（P<0.05），抑制JNK磷酸化（P<0.05）；JNK特异性抑制剂SP600125可下调MRP2蛋白水平（P<0.05）。结论 藤黄酸可增强人胃癌SGC7901/DDP细胞对顺铂的敏感性，这可能与藤黄酸通过抑制JNK信号通路下调MRP2蛋白表达，以及上调Bax蛋白表达和下调Survivin蛋白表达有关。

Enhancing effect of gambogic acid on the sensibility of human gastric carcinoma SGC7901/DDP cells to cisplatin

Objective The aim of this study is to investigate the effect of gambogic acid (GA) on the sensibility of human gastric carcinoma SGC7901/DDP cells to cisplatin (DDP) and its possible mechanism. Methods The drug-resistant SGC7901/DDP cells were established by stepwise exposure to DDP. CCK-8 assay was employed to detect the cytotoxic effect of GA and DDP on SGC7901/DDP cells, and the combined effect of GA and DDP was analyzed by Chou-Talalay method . The cell apoptosis was studied by flow cytometry. Western blotting was performed to detect the protein levels of Bcl-2, Bax, Survivin, multidrug resistance-associated protein 2 (MRP2), phosphorylated c-Jun N-terminal kinase (p-JNK) (Thr183/Tyr185) and JNK. Results The IC₅₀ values of GA and DDP were 2.94 μmol/L and 39.76 μmol/L after 48 hours treatment respectively, and the combined both drugs improved the antitumor effects on SGC7901/DDP cells. GA enhanced cisplatin-induced apoptosis (P<0.05), down-regulated Survivin and MRP2 and up-regulated Bax at the protein level (P<0.05), and inhibited phosphorylation of JNK in SGC7901/DDP cells (P<0.05). SP600125, a specific inhibitor of JNK, declined the protein level of MRP2 (P<0.05). Conclusion GA may enhance the sensibility of SGC7901/DDP cells to cisplatin by down-regulating MRP2 as a result of inactivation of the JNK signaling pathway, and up-regulating Bax and down-regulating Survivin.