Farnesoid X Receptor Agonist GW4064 Inhibits Aromatase and ERβ Expression in Human Endometriotic Stromal Cells

Endometriosis is an estrogen-dependent disease. Farnesoid X receptor (FXR) activation has been shown to inhibit estrogen signaling in breast cancer and testicular tumors. However, the role of FXR in endometriosis is still poorly understood. Here, we aimed to investigate whether FXR activation by its synthetic agonist GW4064 has a therapeutic effect on endometriosis and the underlying molecular mechanisms. We found that the expression of FXR (encoded by the NR1H4 gene) in endometriotic tissues and stromal cells (ESCs) was higher than that in eutopic endometrial tissues and stromal cells. The GW4064 treatment led to a dose-dependent decrease in aromatase and estrogen receptor beta (ER beta) expression and induced ERK1/2, p38, AMPK, and Stat3 activation in ESCs. In contrast, ERK1/2 inhibitor reversed the GW4064-induced reduction in aromatase expression. In addition, treatment with p38, AMPK, and Stat3 inhibitors or small interfering RNAs could also reverse the GW4064-induced reduction of ER beta expression in ESCs. The GW4064 treatment markedly increased Stat3 phosphorylation, enhancing the binding of Stat3 to the ESR2 promoter, which resulted in the downregulation of ER beta. Coimmunoprecipitation assay and chromatin immunoprecipitation analysis revealed that FXR was able to compete with cyclic AMP response element-binding (CREB) protein for binding to a common sequence on the aromatase promoter region after GW4064 treatment in ESCs. Moreover, treatment of endometriosis xenografts with GW4064 suppressed aromatase and ER beta expression in nude mice. Our results suggest that FXR may represent a potential therapeutic target for future therapy.

子宫内膜异位症是一种雌激素依赖性疾病。法尼醇X受体（FXR）的激活已被证明可抑制乳腺癌和睾丸肿瘤中的雌激素信号传导。然而，FXR在子宫内膜异位症中的作用仍知之甚少。在此，我们旨在研究其合成激动剂GW4064激活FXR是否对子宫内膜异位症具有治疗作用以及潜在的分子机制。我们发现FXR（由NR1H4基因编码）在子宫内膜异位组织和基质细胞（ESCs）中的表达高于在位子宫内膜组织和基质细胞。GW4064处理导致芳香化酶和雌激素受体β（ERβ）表达呈剂量依赖性降低，并诱导ESCs中ERK1/2、p38、AMPK和Stat3活化。相反，ERK1/2抑制剂逆转了GW4064诱导的芳香化酶表达降低。此外，用p38、AMPK和Stat3抑制剂或小干扰RNA处理也可逆转GW4064诱导的ESCs中ERβ表达的降低。GW4064处理显著增加Stat3磷酸化，增强Stat3与ESR2启动子的结合，从而导致ERβ下调。免疫共沉淀试验和染色质免疫沉淀分析表明，在ESCs中经GW4064处理后，FXR能够与环磷酸腺苷反应元件结合（CREB）蛋白竞争结合芳香化酶启动子区域上的一个共同序列。此外，用GW4064处理子宫内膜异位症异种移植物可抑制裸鼠中芳香化酶和ERβ的表达。我们的结果表明，FXR可能代表未来治疗的一个潜在治疗靶点。