Changes in protein expression due to metformin treatment and hyperinsulinemia in a human endometrial cancer cell line.

The incidence of endometrial cancer (EC) has increased over the past years and mainly affects women above the age of 45 years. Metabolic diseases such as obesity and type II diabetes mellitus as well as associated conditions like polycystic ovary syndrome (PCOS), insulin resistance and hyperinsulinemia lead to elevated levels of circulating estrogens. Increased estrogen concentrations, in turn, further trigger the proliferation of endometrial cells and thus promote EC development and progression, especially in the absence of progesterone as seen in postmenopausal women. Elevated blood glucose levels in diabetic patients further contribute to the risk of EC development. Metformin is an insulin-sensitizing biguanide drug, commonly used in the treatment of type II diabetes mellitus, especially in obese patients. Besides its effects on glucose metabolism, metformin displayed anti-cancer effects in various cancer types, including EC. Direct anti-cancer effects of metformin target signaling pathways that are involved in cellular growth and proliferation, e.g. the AKT/PKB/mTOR pathway. Further proteins and pathways have been suggested as potential targets, but the underlying mechanism of action of metformin's anti-cancer activity is still not completely understood. In the present study, the effects of metformin on protein expression were investigated in the human EC cell line HEC-1A using an affinity proteomic approach. Cells were treated with 0.5 mmol/L metformin over a period of 7 days and changes in the expression pattern of 1,300 different proteins were compared to the expression in untreated control cells as well as insulin-treated cells. Insulin treatment (100 ng/mL) was incorporated into the study in order to implement a model for insulin resistance and associated hyperinsulinemia, conditions that are often observed in obese and diabetic patients. Furthermore, the culture medium was supplemented with 10 nmol/L ß-estradiol (E2) during treatments to mimic increased estrogen levels, a common risk factor for EC development. Based on the most prominent and significant changes in expression, a set of 80 proteins was selected and subjected to a more detailed analysis. The data revealed that metformin and insulin targeted similar pathways in the present study and mostly acted on proteins related to proliferation, migration and tumor immune response. These pathways may be affected in a tumor-promoting as well as a tumor-suppressing way by either metformin treatment or insulin supplementation. The consequences for the cells resulting from the detected expression changes were discussed in detail for several proteins. The presented data helps identify potential targets affected by metformin treatment in EC and allows for a better understanding of the mechanism of action of the biguanide drug's anti-cancer activity. However, further investigations are necessary to confirm the observations and conclusions drawn from the presented data after metformin administration, especially for proteins that were regulated in a favorable way, i.e. AKT3, CCND2, CD63, CD81, GFAP, IL5, IL17A, IRF4, PI3, and VTCN1. Further proteins might be of interest, where metformin counteracted unfavorable effects that have been induced by hyperinsulinemia.

GRN, NOTCH3, FN1, and PINK1 expression in eutopic endometrium - potential biomarkers in the detection of endometriosis - a pilot study.

PURPOSE: Endometriosis (EM) is a common gynecological disease affecting 10-15% of women of reproductive age. However, molecular mechanisms and pathogenesis are still not completely understood. Furthermore, due to the absence of a reliable clinical biomarker, the only viable method for the often-delayed definitive diagnosis is laparoscopic surgery. Our objective was to analyze molecular differences of selected endometrial proteins and genes of women suffering from different stages of EM compared with healthy women to evaluate potential clinical biomarkers. METHODS: We analyzed eutopic endometrial tissue samples from women undergoing a laparoscopic surgery (n = 58). mRNA gene expression of progranulin (GRN), neurogenic locus notch homolog protein (NOTCH3), fibronectin (FN1), and PTEN-induced kinase 1 (PINK1) was analyzed using qRT-PCR. Protein expression was determined using ELISA and immunohistochemistry. RESULTS: Significant differences in gene expression between the different stages of the disease were noted for GRN, NOTCH3, FN1, and PINK1 (p < 0.05). The endometrium of women with minimal EM (ASRM I) showed the highest mRNA expression. Protein levels of GRN and FN1 on the other hand were significantly decreased in the endometrium of women with EM compared with those of healthy controls. Furthermore, for GRN and FN1, we could detect a correlation of protein expression with the severity of the disease. CONCLUSION: Our findings suggest a potential use of GRN and FN1 as clinical biomarkers to detect endometriosis. In addition, GRN, NOTCH3, FN1, and PINK1 could potentially be useful to differentiate between the underlying stages of the disease. However, a validation with a larger study population is needed.

Endometrial expression of receptivity markers subject to ovulation induction agents.

PURPOSE: Implantation rates differ according to ovulation induction agents in ART. This study investigates the different local endometrial effects of LH- versus hCG-induced ovulation. METHODS: Endometrial stromal cells from healthy patients were cultured with hCG or LH in different concentrations, supplemented with 250 ng/mL hCG and progesterone after 2 and 5 days. In addition after decidualization induction, cells were treated with hCG (50 or 250 ng/mL) or LH (10 or 50 ng/mL) for 3 days. Receptivity markers expression was evaluated by real-time quantitative PCR on day 3 and 6. RESULTS: On day 3, non-decidualized cells treated with LH showed an increased expression of IGFBP1, IL-8 and CXCL12 compared to hCG. The expression pattern changed on day 6, where cells treated with hCG showed higher expression of implantation markers compared to LH-treated cells. Furthermore, on day 3, decidualized cells treated with hCG250 showed an increased IL8 and CXCL12 expression compared to LH10. CONCLUSIONS: LH seems to modulate the local endometrial expression of receptivity markers earlier compared to hCG; however, the effect is not sustained over time in cells without prior decidualization. Though, in decidualized cells, pattern changed and an earlier positive effect of hCG was shown on IL-8 and CXCL12.