Sharifi Simin, Barar Jaleh, Hejazi Mohammad Saeid, Samadi Nasser
Department of Pharmaceutical Biotechnology, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran E-mail :
Asian Pac J Cancer Prev. 2014;15(20):8617-22. doi: 10.7314/apjcp.2014.15.20.8617.
The goal of this study was to establish paclitaxel resistant MCF-7 cells, as in vitro model, to identify the molecular mechanisms leading to acquired chemoresistance in breast cancer cells. Resistant cells were developed by stepwise increasing exposure to paclitaxel. Gene expression levels of Bax and Bcl-2 along with protein levels of caspase-8 and caspase-9 were evaluated in two resistant cell lines (MCF -7/Pac64 and MCF -7/Pac5 nM). Morphological modifications in paclitaxel resistance cells were examined by light microscopy and fluorescence activated cell sorting (FACS). As an important indicator of resistance to chemotheraputic agents, the Bcl-2/Bax ratio showed a significant increase in both MCF-7/Pac5nM and MCF-7/Pac 64nM cells (p<0.001), while caspase-9 levels were decreased (p<0.001) and caspase-8 was increased (p<0.001). FACS analysis demonstrated that MCF -7/Pac64 cells were smaller than MCF-7 cells with no difference in their granularity. Our results support the idea that paclitaxel induces apoptosis in a mitochondrial-dependent manner. Identifying breast cancer patients with a higher Bcl-2/Bax ratio and caspase 9 level and then inhibiting the activity of these proteins may improve the efficacy of chemotheraputic agents.
本研究的目的是建立耐紫杉醇的MCF-7细胞作为体外模型，以确定乳腺癌细胞获得性化疗耐药的分子机制。通过逐步增加对紫杉醇的暴露来培养耐药细胞。在两种耐药细胞系（MCF-7/Pac64和MCF-7/Pac5 nM）中评估Bax和Bcl-2的基因表达水平以及caspase-8和caspase-9的蛋白水平。通过光学显微镜和荧光激活细胞分选（FACS）检查紫杉醇耐药细胞的形态学改变。作为对化疗药物耐药的重要指标，Bcl-2/Bax比值在MCF-7/Pac5nM和MCF-7/Pac 64nM细胞中均显著升高（p<0.001），而caspase-9水平降低（p<0.001），caspase-8升高（p<0.001）。FACS分析表明，MCF-7/Pac64细胞比MCF-7细胞小，其颗粒度无差异。我们的结果支持紫杉醇以线粒体依赖性方式诱导细胞凋亡的观点。识别具有较高Bcl-2/Bax比值和caspase 9水平的乳腺癌患者，然后抑制这些蛋白的活性可能会提高化疗药物的疗效。
