All of these risk factors are also tightly linked to the initiation and progression of EC [23–25]. The anti-cancer effects of metformin Metformin (N,N-dimethylbiguanide), an oral biguanide insulin-sensitizing drug, is the most widely used first-line treatment for type 2 diabetes mellitus worldwide [26, 27]. The primary functions of this drug are to inhibit OSI-027 price hepatic gluconeogenesis and glucose release in the liver (which check details causes decreased circulating glucose and insulin levels), to improve insulin sensitivity, and to enhance glucose uptake and utilization in

peripheral tissues such as skeletal muscle and adipocytes [28–30]. In recent years, multiple lines of evidence have provided support for the hypothesis that treatment with metformin results in decreased incidence, progression, and mortality Epoxomicin in vitro of different human cancers [29, 31, 32] including EC [33, 34]. Although a number of in vitro studies have demonstrated the antiproliferative, anti-invasive, and antimetastatic

effects of metformin in multiple cancer cell types [28], including type I EC-like cancer cells [35–39], its cellular and molecular mechanisms of anti-cancer action in the endometrium of women with PCOS have not yet been fully elucidated [40]. In this review, we will first provide an overview of the beneficial effects that treatment with metformin has on the endometrium of women with both PCOS and associated endometrial

hyperplasia and early-stage EC. We will also address some questions that are relevant to treatment with metformin. Alanine-glyoxylate transaminase The main part of this review will then focus on the diverse expression and regulation of metformin carrier proteins in the endometrium as well as the underlying molecular mechanisms behind the effects of metformin. These mechanisms will be discussed in terms of their potential to contribute to the reversion of early-stage EC to normal endometria in women with PCOS. Review The effects of metformin in endometrial cells The human endometrium undergoes extraordinary growth in a cyclical manner during the childbearing years [41] and is responsive to ovarian steroid hormones (estrogen and progesterone) that are essential for controlling epithelial and stromal cell proliferation, differentiation, secretion, and apoptosis [42]. Because estrogens act as proliferative factors in the endometrial tissue and can lead to endometrial overgrowth and hyperplasia [43], it is presumed that the primary cause of EC is the continuous exposure of the endometrium to estrogens [9, 12]. In fact, endogenous estrogen levels have been shown to be increased up to three fold in women with type I EC compared to healthy women [44].