白屈菜红碱逆转人乳腺癌多药耐药的机制

Mechanism Governing Reversal of Multidrug Resistance in Human Breast Carcinoma Cells by Chelerythrine

目的研究蛋白激酶Cα(PKCα)抑制剂白屈菜红碱(CH)逆转人乳腺癌细胞多药耐药的机制。方法应用RT-PCR和Western blot方法,检测CH和佛波醇酯(PMA)作用于乳腺癌耐药细胞系MCF-7Taxol后,细胞中多药耐药相关基因ABCG2、ABCC1、MDR1和P糖蛋白表达的变化。采用MTT方法,分析给予低剂量CH和PMA(<IC20)后,MCF-7Taxol细胞对紫杉醇以及阿霉素耐药性的变化。结果 RT-PCR和Western blot结果表明:CH可以下调MDR1转录水平(P<0.05),降低P糖蛋白的表达(P<0.05);PMA在提高MDR1转录水平(P<0.05)同时增加P糖蛋白的含量(P<0.05)。MTT分析发现:0.1μmol/L的CH预处理的MCF-7Taxol对紫杉醇和阿霉素耐药性分别降低为加药前的0.17和0.27倍(P<0.01);而使用0.1μmol/L的PMA预处理后,MCF-7Taxol对紫杉醇和阿霉素耐药性分别增加了3.37和2.92倍(P<0.01)。使用CH和PMA处理对MCF-7的作用却不显著(P>0.05)。结论 CH可以逆转人乳腺癌细胞的多药耐药性,其机制可能与抑制PKCα活性,下调MDR1基因转录水平,降低其表达产物P-gp的水平有关。

Objective To explore the mechanism governing the reversal of multidrug resistance in human breast carcinoma cells by chelerythrine.Methods Reverse transcription-polymerase chain reaction（RT-PCR） and Western blot were used to determine the expressions of protein kinase Cα（PKCα） and multidrug resistance-related genes ABCG2,ABCC1,MDR1,and P-glycoprotein（P-gp） in MCF-7Taxol cells after treatment with chelerythrine and phorbol-12-myristate-13-acetate（PMA）.Also,the antitumor effect of PMA or chelerythrine and effects of PKCα activator or inhibitor in combination with paclitaxel or adriamycin on multidrug resistance in MCF-7Taxol cells were evaluated by MTT.Results RT-PCR or Western blot showed that the expressions of MDR1 and P-gp were significantly higher in MCF-7Taxol cells exposed to PMA stimuli（both P0.05）,while chelerythrine significantly down-regulated the expressions of MDR1 and P-gp（both P0.05）.The reversal effectiveness of PKC inhibitors in combination with paclitaxel or adriamycin was apparently favorable.The resistance of MCF-7Taxol cells to paclitaxel or adriamycin was significantly enhanced up by 3.37 or 2.92 folds exposed to 0.1 μmol/L PMA（P0.01）,which was significantly decreased by 0.17 or 0.27 folds exposed to 0.1 μmol/L chelerythrine（P0.01）.After chelerythrine or PMA pre-treating,there was no significant difference in the reversal effectiveness of MCF-7 cells（P0.05）.Conclusion PKCα inhibitor chelerythrine can reverse multidrug resistance in breast carcinoma cells by inhibiting the expressions of MDR1 and P-gp expression in vitro.