Bag-1 stimulates Bad phosphorylation through activation of Akt and Raf kinases to mediate cell survival in breast cancer
Bag-1 stimulates Bad phosphorylation through activation of Akt and Raf kinases to mediate cell survival in breast cancer
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DOI：
10.1186/s12885-019-6477-4
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发表时间：
2019-12-28
期刊：
影响因子：
3.8
通讯作者：
Dinler-Doganay, Gizem
中科院分区：
文献类型：
--
作者：
Kizilboga, Tugba;Baskale, Emine Arzu;Dinler-Doganay, Gizem
背景：Bag-1（Bcl-2相关的凋亡基因）是一种多功能的抗凋亡蛋白，经常在癌症中过度表达。Bag-1与多种细胞靶点相互作用，包括Hsp 70/Hsc 70分子伴侣、Bcl-2、核激素受体、Akt和Raf激酶。在这项研究中，我们详细研究了Bag-1对与乳腺癌相关的主要细胞存活途径的影响。方法：使用免疫印迹分析，我们研究了Bag-1在不同受体状态的乳腺癌患者的肿瘤和正常组织中的表达谱。我们通过在MCF-7、BT-474、MDA-MB-231和MCF-10A乳腺细胞系中实施Bag-1的异位表达或敲低，研究了Bag-1对细胞增殖、凋亡、Akt和Raf激酶通路以及Bad磷酸化的影响。我们还在乳腺癌患者的肿瘤和正常组织中测试了这些。我们通过免疫共沉淀研究了Bag-1、Akt和Raf激酶在细胞系和肿瘤组织中的相互作用，并通过免疫细胞化学和免疫组织化学研究了它们的亚细胞定位。而不管它们的ER、PR和Her 2表达谱如何。Bag-1在乳腺癌细胞系中的异位表达导致B-Raf、C-Raf和Akt激酶的激活，这些激酶在乳腺肿瘤中也上调。Bag-1在乳腺癌细胞中与B-Raf、C-Raf和Akt形成复合物，增强它们的磷酸化和活化，并最终导致促凋亡Bad蛋白在Ser 112和Ser 136处的磷酸化。这导致坏的重新定位到细胞核，并抑制细胞凋亡，有利于细胞survival.Conclusions：总体而言，坏的抑制袋-1通过激活Raf和Akt激酶是一种有效的生存和生长策略，利用乳腺癌细胞。因此，靶向Bag-1和这些激酶之间的分子相互作用可能被证明是一种有效的抗癌疗法。
Background: Bag-1 (Bcl-2-associated athanogene) is a multifunctional anti-apoptotic protein frequently overexpressed in cancer. Bag-1 interacts with a variety of cellular targets including Hsp70/Hsc70 chaperones, Bcl-2, nuclear hormone receptors, Akt and Raf kinases. In this study, we investigated in detail the effects of Bag-1 on major cell survival pathways associated with breast cancer.Methods: Using immunoblot analysis, we examined Bag-1 expression profiles in tumor and normal tissues of breast cancer patients with different receptor status. We investigated the effects of Bag-1 on cell proliferation, apoptosis, Akt and Raf kinase pathways, and Bad phosphorylation by implementing ectopic expression or knockdown of Bag-1 in MCF-7, BT-474, MDA-MB-231 and MCF-10A breast cell lines. We also tested these in tumor and normal tissues from breast cancer patients. We investigated the interactions between Bag-1, Akt and Raf kinases in cell lines and tumor tissues by co-immunoprecipitation, and their subcellular localization by immunocytochemistry and immunohistochemistry.Results: We observed that Bag-1 is overexpressed in breast tumors in all molecular subtypes, i.e., regardless of their ER, PR and Her2 expression profile. Ectopic expression of Bag-1 in breast cancer cell lines results in the activation of B-Raf, C-Raf and Akt kinases, which are also upregulated in breast tumors. Bag-1 forms complexes with B-Raf, C-Raf and Akt in breast cancer cells, enhancing their phosphorylation and activation, and ultimately leading to phosphorylation of the pro-apoptotic Bad protein at Ser112 and Ser136. This causes Bad's re-localization to the nucleus, and inhibits apoptosis in favor of cell survival.Conclusions: Overall, Bad inhibition by Bag-1 through activation of Raf and Akt kinases is an effective survival and growth strategy exploited by breast cancer cells. Therefore, targeting the molecular interactions between Bag-1 and these kinases might prove an effective anticancer therapy.