藤黄酸逆转人结肠癌细胞株SW480奥沙利铂耐药性的作用及机制研究

目的探讨藤黄酸对多药耐药人结肠癌细胞株SW480/L—OHP的耐药逆转及其对多药耐药基因（MDR1）和P-糖蛋白（P—gP）表达的影响。方法采用逐步增加药物浓度的方法建立奥沙利铂耐药结肠癌细胞株SW480/L—OHP。噻唑蓝（MTT）法测定SW480/L-OHP细胞株的耐药指数和藤黄酸在无细胞毒浓度下对结肠癌细胞耐受奥沙利铂的逆转作用，流式细胞术检测细胞凋亡、周期变化，RT—PCR检测各组细胞MDRlmRNA表达水平，Westernblot检测各组细胞P—gP蛋白的表达水平。结果藤黄酸对结肠癌SW480及SW480/LOHP细胞增殖均具有抑制作用，且呈量效关系。奥沙利铂与低毒剂量藤黄酸共同作用SW480/L-OHP细胞，其Ic50显著降低（P〈0．05），耐药逆转倍数为3．72。与奥沙利铂单药组相比，加入低毒剂量藤黄酸后，细胞凋亡率明显增加，差异有统计学意义（P〈0．05）。藤黄酸作用后MDRlmRNA转录水平降低，同时下调了P—gp蛋白表达。结论藤黄酸部分逆转SW480/L—OHP细胞对奥沙利铂的耐药性，其机制与增加细胞内奥沙利铂的蓄积，抑制MDRl基因的表达及降低P—gp的表达有关。

Reversal of resistance to Oxaliplatin in human colon cancer by gambogic acid

Objective To explore the effect of gambogic acid on the reversal of multi-drug resistance and the expressions of the poly multi-drug resistance protein 1 （MDR1） and P-glycopmtein （P-gp） in SW480/ L-OHP cells. Methods Oxaliplatin resistant SW480/L-OHP cells were established by gradually increasing the concentration of L-OHP and intermittent treatment with high-dose concentration on parental cells （SW480）. Methyl thiazolyl tetrazollum （MTF） method was used to detect the reversal index （RI） of SW480/L-OHP cells and the reversal effect of gambogic acid. The cell cycle, apoptosis of cells were determined by flow cytometry assay. Expression of MDR1 mRNA was detected by RT-PCR. Expressions of P-gp proteins were detected by Western blot. All experimental data were dealt with by SPSS13.0 software. Results The inhibitory effect of gambogic acid on both SW480 and SW480/L-OHP was detected in a dose-dependent manner. Low-cytotoxic dose of gambogic acid could obviously decrease the ICs0 value of SW480/L-OHP cells to Oxaliplatin （P 〈 0.05）. The reversing fold was 3.72. Low-cytotoxic dose of gambogic acid could increase the apoptotic rate evidently and remarkably reduce the expression of MDR1 mRNA and decrease the P-gp expression in SW480/L-OHP cells. Conclusion Gambogic acid could partially reverse the multi-drug resistance to Oxaliplatin in SW480/ L-OHP ceils, which is related to the increased accumulation of intracellular Oxaliplatin, the inhibition ofMDR1 gene expression and the decreased expression of P-gp.