Metformin inhibits 17β-estradiol-induced epithelial-to-mesenchymal transition via βKlotho-related ERK1/2 signaling and AMPKα signaling in endometrial adenocarcinoma cells.

Zhao Liu,Jiaju Lu,Hui Zhang,Mingjiang Li,Xingbo Zhao,Shasha Qi,Sentai Ding

doi:10.18632/oncotarget.7040

Abstract

The potential role of metformin in treating endometrial cancer remains to be explored. The current study investigated the role of metformin in 17β-estradiol-induced epithelial-mesenchymal transition (EMT) in endometrial adenocarcinoma cells. We found that 17β-estradiol promoted proliferation and migration, attenuated apoptosis in both estrogen receptor (ER) positive and ER negative endometrial adenocarcinoma cells (Ishikawa and KLE cells, respectively). Metformin abolished 17β-estradiol-induced cell proliferation and reversed 17β-estradiol-induced EMT in Ishikawa cells. In addition, metformin increased the expression of βKlotho, a fibroblast growth factors (FGFs) coreceptor, and decreased ERK1/2 phosphorylation in both Ishikawa and KLE cells. Decreased expression of βKlotho was noted in human endometrial adenocarcinomas, and plasmid-driven expression of βKlotho in Ishikawa cells abolished 17β-estradiol-induced EMT via inhibiting ERK1/2 signaling. βKlotho expression and metformin show synergetic effects on the proliferation and the EMT in Ishikawa cells. Furthermore, we demonstrated that the anti-EMT effects of metformin could be partly abolished by introducing Compound C, a specific AMPKα signaling inhibitor. In conclusion, metformin abolishes 17β-estradiol-induced cell proliferation and EMT in endometrial adenocarcinoma cells by upregulating βKlotho expression, inhibiting ERK1/2 signaling, and activating AMPKα signaling. Our study provides novel mechanistic insight into the anti-tumor effects of metformin.

Highlights

Endometrial adenocarcinoma is the most common gynecological cancer worldwide [1], and one-half of patients died for advanced disease [2]
The Cell Counting Kit-8 (CCK-8) assays were performed to determine the effects of metformin and 17β-estradiol on the proliferation of endometrial adenocarcinoma cell lines, Ishikawa and KLE cells
To determine whether 17β-estradiol and metformin are involved in the epithelialmesenchymal transition (EMT) regulation of endometrial cancer, we examined the expression of EMT-related markers in Ishikawa and KLE cell lines using western blot analysis. 17β-estradiol significantly decreased the expression of E-cadherin and increased the expressions of N-cadherin, Vimentin, and Slug in Ishikawa cells (Figure 4A)

Summary

Introduction

Endometrial adenocarcinoma is the most common gynecological cancer worldwide [1], and one-half of patients died for advanced disease [2]. The loss of E-cadherin is generally accepted as a hallmark of the EMT [8], which reduces cell-cell adhesion and destabilizes the epithelial architecture This process is accompanied by increased expression of mesenchymal-related proteins, including N-cadherin, Vimentin, and fibronectin, which bestow a motile phenotype on cancer cells through changes in cellular architecture and cell-matrix interactions [9, 10]. Many transcription factors, such as Snail and Slug, act as repressors of E-cadherin in response to TGF-β [11]

Methods

Results

Conclusion