Growing evidence suggests that epithelial-mesenchymal transition (EMT) and its regulator mitogen-activated protein kinase (MAPK) contribute to endometria-related reproductive disorders. However, the regulation of EMT and MAPK signalling components in the endometrium from polycystic ovary syndrome (PCOS) patients has not been systematically investigated and remains elusive. In humans, how metformin induces molecular alterations in the endometrial tissues under PCOS conditions is not completely clear. Here, we recruited 7 non-PCOS patients during the proliferative phase (nPCOS), 7 non-PCOS patients with endometrial hyperplasia (nPCOSEH), 14 PCOS patients during the proliferative phase (PCOS) and 3 PCOS patients with endometrial hyperplasia (PCOSEH). Our studies demonstrated that compared with nPCOS, PCOS patients showed decreased Claudin 1 and increased Vimentin and Slug proteins. Similar to increased Slug protein, nPCOSEH and PCOSEH patients showed increased N-cadherin protein. Western blot and immunostaining revealed increased epithelial phosphorylated Cytokeratin 8 (p-CK 8) expression and an increased p-CK 8:CK 8 ratio in PCOS, nPCOSEH and PCOSEH patients compared to nPCOS patients. Although nPCOSEH and PCOSEH patients showed increased p-ERK1/2 and/or p38 protein levels, the significant increase in p-ERK1/2 expression and p-ERK1/2:ERK1/2 ratio was only found in PCOS patients compared to nPCOS patients. A significant induction of the membrane ERβ immunostaining was observed in the epithelial cells of PCOS and PCOSEH patients compared to nPCOS and nPCOSEH patients. While in vitro treatment with metformin alone increased Snail and decreased Claudin 1, N-cadherin and α-SMA proteins, concomitant treatment with metformin and E2 increased the expression of CK 8 and Snail proteins and decreased the expression of Claudin 1, ZO-1, Slug and α-SMA proteins. Our findings suggest that the EMT contributes to the switch from a healthy state to a PCOS state in the endometrium, which might subsequently drive endometrial injury and dysfunction. We also provide evidence that metformin differentially modulates EMT protein expression in PCOS patients depending on oestrogenic stimulation.

中文翻译：

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二甲双胍在体外可部分抑制PCOS妇女子宫内膜上皮-间质转化和MAPK信号转导成分的变化。

越来越多的证据表明，上皮-间质转化（EMT）及其调节性丝裂原活化蛋白激酶（MAPK）与子宫内膜相关的生殖疾病有关。但是，尚未对系统性研究多囊卵巢综合征（PCOS）患者子宫内膜中EMT和MAPK信号转导成分的调控进行研究。在人类中，二甲双胍如何在PCOS条件下诱导子宫内膜组织分子改变尚不清楚。在这里，我们招募了7个非PCOS增生期（nPCOS），7个非PCOS子宫内膜增生（nPCOSEH），14个PCOS增生期（PCOS）和3个PCOS子宫内膜增生（PCOSEH）患者。我们的研究表明，与nPCOS相比，PCOS患者显示克劳丁1减少，波形蛋白和Slug蛋白增加。与Slug蛋白增加相似，nPCOSEH和PCOSEH患者显示N-钙粘蛋白增加。Western印迹和免疫染色显示，与nPCOS患者相比，PCOS，nPCOSEH和PCOSEH患者的上皮磷酸化细胞角蛋白8（p-CK 8）表达增加，并且p-CK 8：CK 8比值增加。尽管nPCOSEH和PCOSEH患者显示p-ERK1 / 2和/或p38蛋白水平升高，但与nPCOS患者相比，仅在PCOS患者中发现p-ERK1 / 2表达和p-ERK1 / 2：ERK1 / 2比率显着增加。与nPCOS和nPCOSEH患者相比，在PCOS和PCOSEH患者的上皮细胞中观察到膜ERβ免疫染色的显着诱导。单独使用二甲双胍的体外治疗可增加Snail并降低Claudin 1，N-钙粘着蛋白和α-SMA蛋白，但同时进行二甲双胍和E2处理可增加CK 8和Snail蛋白的表达，并降低Claudin 1，ZO-1，弹头和α-SMA蛋白。我们的发现表明，EMT有助于子宫内膜从健康状态转换为PCOS状态，这可能随后导致子宫内膜损伤和功能障碍。我们还提供证据表明二甲双胍可根据雌激素刺激差异调节PCOS患者的EMT蛋白表达。我们的发现表明，EMT有助于子宫内膜从健康状态转换为PCOS状态，这可能随后导致子宫内膜损伤和功能障碍。我们还提供证据表明二甲双胍可根据雌激素刺激差异调节PCOS患者的EMT蛋白表达。我们的发现表明，EMT有助于子宫内膜从健康状态转换为PCOS状态，这可能随后导致子宫内膜损伤和功能障碍。我们还提供证据表明二甲双胍可根据雌激素刺激差异调节PCOS患者的EMT蛋白表达。