Shen Yan, Yang Fang, Zhang Wenwen, Song Wei, Liu Yuxiu, Guan Xiaoxiang
Department of Medical Oncology, Jinling Hospital, Medical School of Nanjing University, Nanjing, China.
Department of Medical Oncology, Jinling Hospital, Southern Medical University, Guangzhou, China.
Cell Physiol Biochem. 2017;43(5):2047-2061. doi: 10.1159/000484187. Epub 2017 Oct 23.
BACKGROUND/AIMS: The targeted therapy for triple-negative breast cancer (TNBC) is still challenging due to poor understanding on its molecular etiology. The androgen receptor (AR) has recently emerged as a prognostic and treatment-predictive marker in breast cancer. However, the role of AR in TNBC remained elusive.
Immunohistochemistry (IHC) was used to detect AR and G-protein coupled estrogen receptor (GPER) expression in tissue microarrays of 165 TNBC patients. Microarray analysis of mRNAs was performed to identify downstream regulators of AR. TNBC cells were cultured with dihydrotestosterone (DHT) alone or in combination with AR knockdown performed with AR shRNA. Cell viability and colony formation were assessed. Western blotting and qRT-PCR were used to examine protein and mRNA expression, respectively. The potential mechanism of AR-mediated GPER suppression was identified by Chromatin immunoprecipitation (ChIP) assay. AR and GPER expressions were also assessed in nude mouse xenografts by IHC.
IHC staining showed that the expression of AR was positively associated with tumor size, lymph node metastasis and high-grade tumor in TNBC patients. AR activation triggered by DHT suppressed GPER expression, to promote cell growth of TNBC. G-1, a GPER agonist, inhibited DHT-stimulated proliferation. Further experiments illustrated that AR suppressed GPER activation via binding directly to the promoter of GPER. Moreover, a negative correlation between AR and GPER was observed in MDA-MB-231 tumor cell xenografts and TNBC patient samples.
The suppression of GPER via AR may be involved in the positive actions towards the TNBC progression, making it a promising therapeutic target for TNBC treatment.
背景/目的：由于对三阴性乳腺癌（TNBC）分子病因的了解不足，其靶向治疗仍然具有挑战性。雄激素受体（AR）最近已成为乳腺癌的一种预后和治疗预测标志物。然而，AR在TNBC中的作用仍不明确。
采用免疫组织化学（IHC）检测165例TNBC患者组织芯片中AR和G蛋白偶联雌激素受体（GPER）的表达。进行mRNA微阵列分析以鉴定AR的下游调节因子。TNBC细胞单独用二氢睾酮（DHT）培养或与用AR shRNA进行AR敲低联合培养。评估细胞活力和集落形成。分别使用蛋白质印迹和qRT-PCR检测蛋白质和mRNA表达。通过染色质免疫沉淀（ChIP）试验确定AR介导的GPER抑制的潜在机制。还通过IHC评估裸鼠异种移植瘤中的AR和GPER表达。
IHC染色显示，TNBC患者中AR的表达与肿瘤大小、淋巴结转移和高级别肿瘤呈正相关。DHT触发的AR激活抑制了GPER表达，从而促进TNBC的细胞生长。GPER激动剂G-1抑制了DHT刺激的增殖。进一步的实验表明，AR通过直接结合GPER的启动子抑制GPER激活。此外，在MDA-MB-231肿瘤细胞异种移植瘤和TNBC患者样本中观察到AR和GPER之间呈负相关。
AR对GPER的抑制可能参与了TNBC进展的正向作用，使其成为TNBC治疗的一个有前景的治疗靶点。
