mTOR激酶抑制剂依赖Bim诱导MDA-MB-453乳腺癌细胞死亡

mTOR kinase inhibitor inducing MDA-MB-453 breast cancer cell death by depending on Bim

目的研究哺乳动物雷帕霉素靶蛋白(mTOR)激酶抑制剂MTI-31诱导乳腺癌细胞凋亡的作用与机制。方法分别构建MDA-MB-453和HCC1806异种移植瘤模型,通过灌胃和尾静脉注射分别给予MTI-31和多西他赛,监测肿瘤体积与小鼠体重;利用蛋白免疫印迹(Western blot)检测给药后凋亡相关生物标志蛋白Cleaved PARP和Bim的水平;利用shRNA特异性敲减Bim,随后应用细胞计数法研究药物对细胞生存的影响;采用免疫组织化学观察皮下瘤中Bim的表达情况。结果MTI-31可使MDA-MB-453异种移植瘤消退,但仅抑制HCC1806异种移植瘤的生长,其疗效与多西他赛相近。在体外,敲减MDA-MB-453中的Bim后,MTI-31、拉帕替尼和多西他赛的药效明显降低,雷帕霉素只是抑制了肿瘤生长;敲减Bim后的MDA-MB-453中,MTI-31处理的shBim 2组Cleaved PARP和Bim的表达水平较shNT组明显减少(P<0.01)。在MDA-MB-453皮下瘤中,MTI-31处理组的Bim表达较溶剂处理组显著增加。结论mTOR激酶抑制剂MTI-31可诱导MDA-MB-453乳腺癌细胞凋亡性死亡且依赖于Bim。

Objective To investigate the effect and mechanism of cell apoptosis of breast cancer induced by mTOR kinase inhibitor MTI-31.Methods The xenograft models of MDA-MB-453 and HCC1806 were constructed respectively.MTI-31 and docetaxel were administrated via gavage and tail vein accordingly.Meanwhile,the tumor volume and body weight of mice were monitored.Western blot assay was employed to examine the apoptosis related biomarkers Cleaved PARP and Bim levels.Then,Bim was knocked down by using shRNA.Then,the cell counting method was used to study the effect of drugs on cell survival.The expression level of Bim was determined by using the immunohistochemistry assay.Results MTI-31 could cause the MDA-MB-453 heterograft regression,but only inhibited the growth of HCC1806 xenograft,its effect was similar to docetaxel.In vitro,when knocking down the expression of Bim in MDA-MB-453,the pharmaceutical effects of MTI-31,lapatinib and docetaxel were significantly decreased.In the MDA-MB-453 cells after knocking down Bim,the expression levels of Cleaved PARP and Bim in the shBim 2 group treated with MTI-31 was remarkably reduced when compared with the shNT group which also treated with MTI-31(P<0.01).In MDA-MB-453 subcutaneous tumors,the Bim expression in the MTI-31 treatment group was significantly increased when compared with the solvent treatment group.Conclusion The mTOR kinase inhibitor MTI-31 could induce the Bim-dependent apoptotic death in breast cancer cell of MDA-MB-453.