Gong Wei, Qin Yi-yu, Li Song-gang, Quan Zhi-wei, Li Ji-yu, Zhuang Peng-yuan, Wan Zi-wei
Department of General Surgery, Xinhua Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200092, China.
Zhonghua Yi Xue Za Zhi. 2010 Oct 19;90(38):2718-22.
To investigate the possible mechanisms by which Somatostatin (SST) enhances the anti-tumor effect of doxorubicin (DOX) on gallbladder cancer cells.
GBC-SD cells were grouped into 4 groups: SST-treated group, DOX-treated group, SST+DOX co-treated group and control group. The concentrations of SST and DOX were 75 µg/ml and 5 µg/ml based on our previous studies. In control group, cells were cultivated with phosphate buffered saline (PBS). In experimental groups, cells were cultivated with medium and the corresponding drugs. After drug treatment, cell viability was examined by MTT assay at 6, 12, 24 and 36 h respectively. Meanwhile, intracellular concentrations of doxorubicin in each group was determined by microspectrofluorimetry; Real-time polymerase chain reaction (RT-PCR) was used to determine the expressions of MDR1 mRNA in the cells at different time points and the expressions of P-gp protein, a product of MDR1 mRNA, were determined by Western blot analysis.
SST did not exhibit significant inhibitory effect on the proliferation of GBC-SD cells as compared to that of control group (P>0.05). SST+DOX co-treatment group and DOX showed significantly inhibitory effect on the growth of GBC-SD cells at Hour 12 post-treatment. However no statistical difference was found between SST+DOX and DOX groups. Interestingly, at Hour 24 post-treatment, SST+DOX group showed more robust inhibitory effect on GBC-SD cells as compared to DOX alone group. Moreover, SST could significantly down-regulate the expressions of MDR1 mRNA and P-gp protein. SST could increase intracellular DOX concentration. And the difference of intracellular DOX concentration between SST+DOX group and DOX group at Hour 24 was statistically significant.
In our experiment, SST decreases the expression of MDR1 mRNA and P-gp protein so as to reduce the efflux of DOX and elevate DOX concentrations in GBC-SD cells. This eventually leads to enhanced cytotoxic effects of DOX on GBC-SD cells.
探讨生长抑素（SST）增强阿霉素（DOX）对胆囊癌细胞抗肿瘤作用的可能机制。
将GBC-SD细胞分为4组：SST处理组、DOX处理组、SST+DOX联合处理组和对照组。根据我们之前的研究，SST和DOX的浓度分别为75μg/ml和5μg/ml。对照组细胞用磷酸盐缓冲盐水（PBS）培养。在实验组中，细胞用培养基和相应药物培养。药物处理后，分别在6、12、24和36小时通过MTT法检测细胞活力。同时，用显微分光荧光法测定每组细胞内阿霉素的浓度；采用实时聚合酶链反应（RT-PCR）测定不同时间点细胞中MDR1 mRNA的表达，并通过蛋白质免疫印迹分析测定MDR1 mRNA产物P-糖蛋白（P-gp）的表达。
与对照组相比，SST对GBC-SD细胞的增殖未表现出显著抑制作用（P>0.05）。SST+DOX联合处理组和DOX在处理后12小时对GBC-SD细胞的生长均表现出显著抑制作用，但SST+DOX组与DOX组之间无统计学差异。有趣的是，在处理后24小时，SST+DOX组对GBC-SD细胞的抑制作用比单独使用DOX组更强。此外，SST可显著下调MDR1 mRNA和P-gp蛋白的表达。SST可增加细胞内DOX浓度。SST+DOX组与DOX组在24小时时细胞内DOX浓度的差异具有统计学意义。
在我们的实验中，SST降低MDR1 mRNA和P-gp蛋白的表达，从而减少DOX的外排并提高GBC-SD细胞内DOX的浓度。这最终导致DOX对GBC-SD细胞的细胞毒性作用增强。
