Different BAG-1 isoforms have distinct functions in modulating chemotherapeutic-induced apoptosis in breast cancer cells
Different BAG-1 isoforms have distinct functions in modulating chemotherapeutic-induced apoptosis in breast cancer cells
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不同的 BAG-1 亚型在调节化疗诱导的乳腺癌细胞凋亡中具有不同的功能
DOI：
10.1038/aps.2008.21
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发表时间：
2009-02-01
影响因子：
8.2
通讯作者：
Chen, Jun
中科院分区：
文献类型：
--
作者：
Liu, Hong-yu;Wang, Zhuo-min;Chen, Jun
目的：BAG-1是一种多功能的抗凋亡基因，有四种亚型，不同亚型的BAG-1具有不同的抗凋亡功能。本研究将BAG-1亚型分别导入ER阴性的人乳腺癌细胞Hs578T和ER阳性的乳腺癌细胞MCF-7，研究其在雌激素作用下对细胞凋亡的影响。方法：构建携带BAG-1亚型的重组表达载体，分别转染ER阴性的Hs578T和ER阳性的MCF-7细胞。建立稳定的细胞系后，用阿霉素、多西紫杉醇和5-FU等多种诱导细胞凋亡的药物，分别在雌激素和不加雌激素的情况下处理这些细胞系，以检测BAG-1的作用。结果：流式细胞仪分析表明，Bag-1的p50和p46亚型明显增强了两种细胞的抗凋亡能力。BAG-1p33和p29不能保护转染组细胞的凋亡。细胞存活率分析显示，只有Bag-1p50，而不是p46、p33或p29能增加ER阳性细胞系MCF-7的雌激素依赖功能。只有BAG-1p50在雌激素存在下显著增强其抗凋亡能力，而雌激素对其他BAG-1亚型的抗凋亡能力影响很小。Western印迹检测细胞K-ras、Hsp70、细胞色素c、Raf-1、ER-α、BAG-1、BAG-1、BAG-结论：不同亚型的Bag-1在乳腺癌细胞中具有不同的抗凋亡作用，Bag-1的不同亚型可增强雌激素在ER阳性乳腺癌中的作用。
Aim: BAG-1 is a multifunctional anti-apoptotic gene with four isoforms, and different BAG-1 isoforms have different antiapoptotic functions. In this study, we transfected BAG-1 isoforms into the human breast cancer cell lines Hs578T (ER negative) and MCF-7 (ER positive) to study their effect on apoptosis with or without estrogens.Methods: The constructed recombinant expression vectors carrying individual BAG-1 isoforms was used to transfect human breast cancer cell lines Hs578T (ER negative) and MCF-7 (ER positive). After stable cell lines were made, a variety of apoptosis-inducing agents, including doxorubicin, docetaxel, and 5-FU, was used to treat these cell lines with or without estrogen to test the role of BAG-1. The mechanism by which BAG-1 affected the function of Bcl-2 was exploredby using the cycloheximide chase assay.Results: The BAG-1 p50 and p46 isoforms significantly enhanced the resistance to apoptosis in both cell lines according to flow cytometry analysis. BAG-1 p33 and p29 failed to protect the transfected cells from apoptosis. The cell viability assay showed that only BAG-1 p50, but not p46, p33, or p29, increased estrogen-dependent function in ER-positive cell line MCF-7. Only BAG-1 p50 dramatically increased its anti-apoptotic ability in the presence of estrogen, while estrogen has very little effect on the anti-apoptotic ability of other BAG-1 isoforms. In the detection of the expression of K-ras, Hsp70, cytochrome c, Raf-1, ER-alpha, and Bcl-2 in MCF-7 cells by Western blot, only Bcl-2 protein expression was significantly increased in MCF-7 cells transfected with BAG-1 p50 and p46, respectively. Furthermore, the cycloheximide chase assay indicated that the degradation of Bcl-2 protein was extended in the BAG-1 p50 and p46 transfected MCF-7 cells.Conclusion: Distinct isoforms of BAG-1 have different anti-apoptotic functions in breast cancer cells, and that the BAG-1 p50 isoform can potentiate the role of estrogen in ER-positive breast cancer.