Effect Of Metformin In Combination Research Articles

Abstract 4126: Synergism of polyamine synthesis inhibition and AMP kinase activation on human melanoma proliferation and migration

Abstract Introduction: Metformin has been shown to inhibit human cancer cell growth via activation of MAP kinase with resultant inhibition of mTOR signaling pathway. We have reported the over-expression of ornithine decarboxylase (ODC) in human melanoma cell lines. ODC is a key enzyme in polyamine biosynthesis. We determined the effect of metformin in combination with DMFO, an ODC inhibitor, on tumor proliferation and migration, and the possible mechanisms, using human melanoma cells. Methods: Human melanoma cells were treated with Metformin, DFMO, or combination. Cell proliferation assay was performed using Cell Titer Blue proliferation assay. Cell migration assay was performed by seeding melanoma cells in 24-well plate. After overnight incubation, an artificial homogenous wound was created onto the monolayer with a plastic micropipette tip. After wounding, the migration of cells into the wound was observed at 0- and 48-hour time points. Quantitative RT-PCR for ODC1 detection was performed using Assay-on-Demand Hs00159739-ml. GAPDH served as housekeeping control. Western blotting was performed to determine the expression of AMP kinase, mTOR, p70S6K and 4E-BP1, Raf-1 and Raf-B. Data were presented as means ± SD for the three separate experiments. For comparison between groups, the student's t test was used and p< 0.05 was considered to be statically significant. Results: There was dose-dependent inhibition of melanoma cell proliferation and migration with either metformin or DFMO. Synergistic inhibition was observed with the combination treatment on both cell migration and proliferation. There was synergistic inhibition of ODC expression with the combined treatment compared with DFMO alone (p<0.01). The combination treatment also lead to significant enhancement of AMPK activation and increased phosphorylation of AMPKΨ at Thr-172 compared with metformin alone (p<0.01). The combination treatment resulted in inhibition of mTOR signaling with decreased phosphorylation of mTOR, p70S6K and 4E-BP1, Raf-1 and Raf-B in treated cancer cells, when compared with individual drug treatments. Conclusion: We have observed a synergistic effect of AMP kinase activation and polyamine synthesis inhibition on suppressing human melanoma proliferation and migration. The synergism is due to enhanced inhibition of both polyamine synthesis and mTOR signaling pathways. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4126. doi:1538-7445.AM2012-4126

Impact of rosiglitazone and metformin on serum pro‐inflammatory molecules and adipocytokines in rats with chronic fructose diet

Metabolic syndrome is a pathological condition involving metabolic abnormalities: abdominal obesity, hyperinsulinemia, dyslipidemia, impaired glucose uptake, all of them linked with increased risk for DM2, and CVD. Those alterations are closely related to a chronic inflammation promoting endothelial dysfunction, and other reactants of acute and chronic phases. Adipose tissue produces adipokines that integrate endocrine, autocrine and paracrine signals, contributing to inflammation. We aimed to explore the in vivo effect of metformin and rosiglitazone in fructose‐fed rats.We evaluated sICAM‐1, TNF‐α, IL‐6, IL‐1β, C‐Reactive Protein, leptin, adiponectin, and glucose, triglycerides, uric acid, HDL‐C and LDL‐C. Drugs were administered alone or combined for 3 mo, in rats fed 30% fructose for 4 mo. At month 6 with fructose diet, altered glucose, triglycerides and uric acid, were observed. Fructose induced changes in IL‐6 and IL‐1β at month 7, not observed in rats treated with metformin. Combined therapy decreased weight and normalized leptin and IL‐1β. Thus, increase in IL‐6 and IL‐1β after fructose intake, evidence inflammation, normalized by the combined effect of metformin and rosiglitazone, and harmonizes with decreased leptin and weight loss.Supported in part by grant PICDS08‐69 from ICyT‐G.D.F., México.

Abstract 4355: Metformin potentiates the efficacy of radiotherapy of tumors by eliminating cancer stem cells

Abstract Metformin, a widely used drug for type II diabetes, possess significant anti-cancer property. In a recent study, metformin was able to selectively kill chemoresistant cancer stem cells (CSCs). It has been known that CSCs are resistant to irradiation and, thus, they are responsible for the recurrence of cancer after radiotherapy. The purpose of the present study was to investigate whether metformin enhances the response of tumors to radiotherapy by eradicating radioresistant CSCs. An incubation with metformin at 0.1 mM – 10 mM for 72 hours caused clonogenic cell death in a dose-dependent manner in MCF-7 human breast cancer cells, MIA PaCa-2 human pancreatic cancer cells, and FSaII mouse fibrosarcoma cells. In addition, the clonogenic cell death was enhanced by using the combination of metformin and irradiation. We then investigated the effect of metformin on CSCs of the three cell lines, which were identified by ALDH-1 activity, CD24low/CD44+ expression, and SP method. Metformin was preferentially cytotoxic to CSCs in all these cell lines. The formation of mammospheres from MCF-7 cells was also markedly inhibited by metformin. Both metformin and irradiation activated AMPK and suppressed the mTOR-S6K signaling pathway. Combined treatment of cells with metformin and irradiation was far more effective in activating AMPK and suppressing the mTOR-S6K pathway. The combined effects of metformin and X-irradiation on the growth of FSaII tumors induced in the hind legs of C3H mice were studied. Metformin treatment at 50 – 100 mg/kg/day, i.p., slightly suppressed the tumor growth, but it strikely potentiated the response of tumors to 20 Gy X-irradiation in a single exposure. It was likely that metformin treatment depleted the radioresistant CSCs in the tumors, thereby markedly enhancing the response of tumors to irradiation. However, in addition to killing CSCs, the possibility that metformin radiosensitized CSCs as well as non-CSCs could not be excluded. Our results demonstrated for the first time that metformin is potentially useful for enhancing the efficacy of radiotherapy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4355. doi:10.1158/1538-7445.AM2011-4355