Bicalutamide拮抗AR靶向治疗ER和PR阴性乳腺癌及作用机制研究

Triple-negative breast cancer (TNBC) (Estrogen receptor, ER-negative; Progesterone receptor, PR-negative; Human epidermal growth factor receptor-2, Her2-negative) and Her2 overexpression type breast cancer (ER-negative; PR-negative; Her2-positive) are two high risk breast cancers,which lack the effective and specific therapy. The androgen receptor (AR) is frequently expressed in TNBC and Her2 overexpression breast cancer with the expression rate of 36% and 76% respectively. Bicalutamide is commonly used in prostate cancer treatment. AR inhibitors may antagonize AR therapy which remains largely unknown in breast cancer. We observe that Bicalutamide could not only inhibit MDA-MB-231 and MDA-MB-453 cell proliferation and promote apoptosis, but also inhibit tumor growth and decrease tumor size in vivo and in vitro experiments.According to the close relationship between AR and Wnt/β-catenin,they could constuct a transcription complex,which regulate AR target gene and Wnt downstream gene expression. Therefore,affecting the fomation of the transcription complex with AR inhibitors can in inhibit transcription of AR targeted gene and downstream gene expression of Wnt.If this hypothesis is confirmed, we should provide practical and theoretical basis to targeted AR therapy. AR antagonist may be used in clinic as a therapeutic target for ER-/PR-/AR+ breast cancers.

三阴和Her2过表达型乳腺癌侵袭性高、预后差且治疗方法有限，寻找新的有效治疗方法显得尤为重要。有研究报道AR在三阴和Her2+型乳腺癌中阳性率高，分别为36%和76%。然而，对ER-/PR-/AR+乳腺癌是否可采用拮抗AR治疗是一个值得关注的重要问题。Bicalutamide是治疗前列腺癌的AR拮抗剂，但能否治疗ER-/PR-/AR+乳腺癌及其作用机制还不明确。我们前期在两种乳腺癌细胞系完成了体内和体外一些实验研究，观察到Bicalutamide可以抑制肿瘤细胞增殖、使肿瘤组织体积缩小等现象。鉴于Wnt/β-catenin信号通路与AR关系密切，我们推测β-catenin与AR结合形成转录复合物共同调控AR靶基因转录和Wnt通路下游基因，用AR拮抗剂后影响该转录复合物形成从而抑制AR靶基因转录和Wnt下游基因表达。该假说如被证实，将为实现AR抑制剂靶向治疗此类乳腺癌提供实践基础和理论依据。

目的：Her2过表达型和三阴乳腺癌是ER和PR均为阴性的乳腺癌亚型，此类乳腺癌与ER阳性乳腺癌比较侵袭性高、预后差且无法应用内分泌和（或）靶向治疗，寻找新的有效治疗方法显得尤为重要。方法：研究510例乳腺癌AR不同表达在四种亚型中表发达情况和预后，采用MTT、克隆形成实验和凋亡检测Bicalutamide拮抗AR对MDA-MB-453和MDA-MB-231细胞增殖的抑制作用；裸鼠负荷瘤体内检测Bicalutamide拮抗AR对增殖和凋亡的抑制作用, 肿瘤组织体积缩小；慢病毒转染分别沉默AR和β-catenin采用细胞免疫組化、免疫共沉淀、qRT-PCR和Western-Blot证实Wnt/β-catenin信号通路与AR关系密切，β-catenin与AR结合形成转录复合物共同调控AR靶基因转录和Wnt通路下游基因CMYC。结果：三阴和Her2+型乳腺癌中AR阳性表达率高，分别为39%和76%。无论是ER阴性、ER阳性还是在总体乳腺癌中AR阳性表达患者5年总生存率（5Year-OS rate）较高（ER阴性P=0.007；ER阳性P=0.001；总体患者P=0.001）。Bicalutamide拮抗AR在ER阴性乳腺癌细胞系中抑制增值和促进凋亡，在裸鼠负荷瘤中不但可以抑制肿瘤增殖还可使肿瘤减小,抑制肿瘤组织的生长促进凋亡。并证实形成AR与β-catenin转录复合物，Bicalutamide拮抗AR后影响该转录复合物形成从而抑制AR靶基因转录和Wnt下游基因CMYC表达和转录。结论：该研究项目和实验结果将为实现临床应用Bicalutamide靶向AR抑制剂Her2过表达型和三阴乳腺癌中AR阳性乳腺癌患者提供实践基础和理论依据。