Abstract
Obesity increases the risk of developing cancers for both males and females. This study investigated potential crosstalk between estradiol and leptin signaling pathways within the endometrium of high-fat-diet-induced obese ovariectomized mice to gain insight into possible links between obesity and endometrial cancer. We administered 17-β estradiol (0.2 μg/mouse subcutaneously) and/or recombinant mouse leptin (1 μg/g Bwt intraperitoneally.,) for 20 h to high-fat-diet-induced obese ovariectomized mice. The uterine tissues of experimental animals after treatments were studied by histological, immunohistochemical, quantitative real-time PCR (gene/miRNAs), and methylation-specific PCR analyses. Quantitative real-time PCR analysis revealed significantly increased expression of Cyclin d1, Esr1, Igf1, Igfbp2, Vegf, Oct4, and Pgr after estradiol and leptin co-treatment. Methylation-specific PCR results indicated that the hormonal dependent transcriptional regulation of Vegf, Igf1, and Pgr is independent of promoter methylation. The decreased expression of mmu- miR-204-5p after estradiol and leptin treatments correlated with the increased expression of long non-coding RNA Neat1. Insilico analysis confirmed the interaction of Neat1 and mmu- miR-204-5p and gene targets of mmu-miR-204-5p, including Igf1 were analyzed in this study. Immunohistochemical analyses revealed subcellular localization and increased expression of ESR, VEGF, phospho-Estrogen Receptor-α (pTyr537), and LEPR proteins following estradiol and leptin exposure. Overall, the data from our in vivo studies suggest the regulation of Neat1-mmu-miR-204-5p- Igf1 axis and associated gene expression changes in uterine tissue after estradiol and leptin co-treatment. In humans, long-term exposure to estradiol and leptin can alter endometrial homeostasis through the NEAT1-miR-204-5p-Igf1 axis and favor carcinogenic pathways, which provide mechanistic insight into the obesity-associated endometrial cancer.