Proliferation and metastatic potential of endometrial cancer cells in response to metformin treatment in a high versus normal glucose environment.

In order to improve our understanding of the potential preventive and therapeutic role of metformin, the present study aimed to investigate the capability of low-dose metformin in the efficient inhibition of cancer development and the reduction of the metastasis of endometrial adenocarcinoma type I and primary endometrial epithelial cells (eEPs), with the drug acting as a treatment in a hyperinsulinemic environment exposed to high and normal glucose conditions. The Ishikawa endometrial adenocarcinoma cell line and primary eEPs were exposed to an environment with high (17 mM) or normal glucose (5 mM) and treated with insulin, low-dose metformin (0.1 mM) or a combined treatment. Metastatic potential was assessed by migration and invasion assays, and relative cell proliferation was determined. Metformin at a low dose potently inhibited the insulin action, decreasing the ability of the endometrial cancer (EC) cell line to migrate and invade in a high and normal glucose environment, and decreasing the migration ability of the primary eEPs. In the EC cell line, the insulin treatment increased the proliferation, without any subsequent reduction of proliferation by the addition of 0.1 mM metformin; however, relative cell proliferation sensitivity to metformin was observed in the range between 1 and 5 mM regardless of the glucose concentration present. Overall, metformin at 0.1 mM is not efficient enough to decrease the proliferation in an EC cell line. However, at this concentration, metformin can inhibit the insulin action in endometrial epithelial cancer cells, demonstrating an anti-metastatic effect in high and normal glucose environments.

Are growth factor receptors modulated by metformin in human endometrial stromal cells after stimulation with androgen and insulin?

OBJECTIVE: To assess the effect of metformin on gene and protein expression of insulin receptor (IR) and IGF-1 (IGF-1R) receptor in human endometrial stromal cells after stimulation with androgen and insulin. STUDY DESIGN: Primary culture of endometrial stromal cells stimulated with estrogen, progesterone with or without androgen or insulin, and treated with metformin for 24 and 48 h, followed by RNA (qRT-PCR) and protein (Western blot) extraction and analysis. RESULTS: IR gene expression was increased after treatment with insulin (2.9-fold change, p = 0.027) and further after metformin treatment (4.7-fold change, p < 0.001), and in IGF-1R, the group treated with insulin (1.83-fold change) and metformin (1.78-fold change) showed more expression, than control group (p < 0.001). Similarly, IR protein expression was increased after addition of metformin and insulin (249,869 ± 15,878) in relation to the other groups (p < 0.001). Furthermore, cells treated with insulin (153,634 ± 29,123) and androgen plus insulin (162,854 ± 86,258) had a higher IR protein expression compared to control (104,654 ± 5,634) and androgen group (71,595 ± 3,439, (p = 0.045 and 0.021). In groups treated with insulin (127,711 ± 4,591) and androgen plus insulin (151,098 ± 5,194) the protein IGF-1R was increased compared to control (79,355 ± 3,470) and the androgen-only group (79,326 ± 3,114) (p < 0.001). CONCLUSION: Metformin in combination with insulin increased IR protein and gene expressions, while it had no influence on the protein expression of IGF-1R in endometrial stromal cells.

Metformin modulates PI3K and GLUT4 expression and Akt/PKB phosphorylation in human endometrial stromal cells after stimulation with androgen and insulin.

OBJECTIVE: To assess the effect of metformin on expression of Akt, ERK, PI3K and GLUT4, proteins associated with the growth factor signaling cascade, in human endometrial stromal cells after stimulation with androgen and insulin. STUDY DESIGN: Primary culture of endometrial stromal cells were stimulated in different groups with estrogen, progesterone, androgen and insulin and treated with metformin for 10min, 24h and 48h. After 14 days, proteins were extracted for Western blot analysis. RESULTS: PI3K and GLUT4 expression were increased in the insulin-treated group and further attenuated when metformin was added. The ERK protein was not affected, whereas the Akt phosphorylation was significantly decreased by the action of metformin. CONCLUSION: Metformin affects human endometrial stromal cells by acting on proteins related to growth factors, usually increasing their expression when combined with insulin. Akt phosphorylation was inhibited by metformin, possibly due to its anti-proliferative action.