Zhu Aiyu, Li Yan, Song Wei, Xu Yumei, Yang Fang, Zhang Wenwen, Yin Yongmei, Guan Xiaoxiang
Cell Physiol Biochem. 2016;38(3):1003-14. doi: 10.1159/000443052. Epub 2016 Mar 4.
BACKGROUND/AIMS: Androgen receptor (AR), a steroid hormone receptor, has recently emerged as prognostic and treatment-predictive marker in breast cancer. Previous studies have shown that AR is widely expressed in up to one-third of triple-negative breast cancer (TNBC). However, the role of AR in TNBC is still not fully understood, especially in mesenchymal stem-like (MSL) TNBC cells.
MSL TNBC MDA-MB-231 and Hs578T breast cancer cells were exposed to various concentration of agonist 5-α-dihydrotestosterone (DHT) or nonsteroidal antagonist bicalutamide or untreated. The effects of AR on cell viability and apoptosis were determined by MTT assay, cell counting, flow cytometry analysis and protein expression of p53, p73, p21 and Cyclin D1 were analyzed by western blotting. The bindings of AR to p73 and p21 promoter were detected by ChIP assay. MDA-MB-231 cells were transplanted into nude mice and the tumor growth curves were determined and expression of AR, p73 and p21 were detected by Immunohistochemistry (IHC) staining after treatment of DHT or bicalutamide.
We demonstrate that AR agonist DHT induces MSL TNBC breast cancer cells proliferation and inhibits apoptosis in vitro. Similarly, activated AR significantly increases viability of MDA-MB-231 xenografts in vivo. On the contrary, AR antagonist, bicalutamide, causes apoptosis and exerts inhibitory effects on the growth of breast cancer. Moreover, DHT-dependent activation of AR involves regulation in the cell cycle related genes, including p73, p21 and Cyclin D1. Further investigations indicate the modulation of AR on p73 and p21 mediated by direct binding of AR to their promoters, and DHT could make these binding more effectively.
Our study demonstrates the tumorigenesis role of AR and the inhibitory effect of bicalutamide in AR-positive MSL TNBC both in vitro and in vivo, suggesting that AR inhibition could be a potential therapeutic approach for AR-positive TNBC patients.
背景/目的：雄激素受体（AR）作为一种类固醇激素受体，最近已成为乳腺癌的预后和治疗预测标志物。先前的研究表明，AR在高达三分之一的三阴性乳腺癌（TNBC）中广泛表达。然而，AR在TNBC中的作用仍未完全了解，尤其是在间充质干细胞样（MSL）TNBC细胞中。
将MSL TNBC MDA-MB-231和Hs578T乳腺癌细胞暴露于不同浓度的激动剂5-α-二氢睾酮（DHT）或非甾体拮抗剂比卡鲁胺中，或不进行处理。通过MTT法、细胞计数、流式细胞术分析确定AR对细胞活力和凋亡的影响，并通过蛋白质印迹法分析p53、p73、p21和细胞周期蛋白D1的蛋白质表达。通过染色质免疫沉淀（ChIP）试验检测AR与p73和p21启动子的结合。将MDA-MB-231细胞移植到裸鼠体内，测定肿瘤生长曲线，并在DHT或比卡鲁胺处理后通过免疫组织化学（IHC）染色检测AR、p73和p21的表达。
我们证明AR激动剂DHT在体外诱导MSL TNBC乳腺癌细胞增殖并抑制凋亡。同样，激活的AR在体内显著增加MDA-MB-231异种移植瘤的活力。相反，AR拮抗剂比卡鲁胺可导致凋亡并对乳腺癌生长产生抑制作用。此外，DHT依赖的AR激活涉及细胞周期相关基因的调控，包括p73、p21和细胞周期蛋白D1。进一步研究表明，AR通过直接结合p73和p21的启动子来调节它们，并且DHT可使这些结合更有效。
我们的研究证明了AR在体外和体内对AR阳性MSL TNBC的肿瘤发生作用以及比卡鲁胺的抑制作用，表明抑制AR可能是AR阳性TNBC患者的一种潜在治疗方法。
