Diabetes is associated with an increased risk of developing and dying from cancer. This increased risk may be due to hyperglycemia, hyperinsulinemia, and insulin resistance or other factors. Metformin has recently gained much attention as it appears to reduce cancer incidence and improve prognosis of patients with diabetes. In vitro data and animal studies support these findings from human epidemiological studies. Metformin has multiple potential mechanisms by which it inhibits cancer development and growth. For example, metaformin inhibits hepatic gluconeogenesis, thus decreasing circulating glucose levels, and it increases insulin sensitivity, thus reducing circulating insulin levels. Intracellularly, metformin activates AMPK, which decreases protein synthesis and cell proliferation. Metaformin also reduces aromatase activity in the stromal cells of the mammary gland. Finally, metformin may diminish the recurrence and aggressiveness of tumors by reducing the stem cell population and inhibiting epithelial to mesenchymal transition. Here, we discuss the metabolic abnormalities that occur in tumor development and some of the mechanisms through which metformin may alter these pathways and reduce tumor growth.
"Studies have increasingly focused on the association between metformin and cancer (4) due to data showing that metformin may reduce the risk of cancer in and improve the prognosis of type II diabetes (5,6). The inhibitory effect of metformin on cancer development and tumor growth is not yet clearly understood, but it may be due to the induction of reductions in systemic glucose and insulin levels (4). Conversely, numerous studies have demonstrated that metformin causes apoptosis and may directly inhibit cell proliferation and induce cell death (7–9). "
[Show abstract][Hide abstract] ABSTRACT: Metformin is a guanidine derivative found in Galega officinalis that is commonly used to treat diabetes mellitus. The mechanism of action of metformin involves regulation of the adenosine monophosphate-activated protein kinase/mammalian target of rapamycin signaling pathway, which is implicated in the control of protein synthesis and cell proliferation. This led to the hypothesis that metformin reduces the risk of cancer and slows tumor growth. Thus, in the present study, the effectiveness of metformin as an antiglioma agent was evaluated using the human T98G glioblastoma multiforme cell line. The viability of the T98G cells was assessed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Apoptosis was monitored by measuring caspase-3 levels, as well as by terminal deoxynucleotidyl transferase dUTP nick end labeling and staining with acridine orange and ethidium bromide. The results demonstrate that metformin reduced cell viability and caused apoptotic morphological changes in the T98G cells. Furthermore, the caspase-3 levels in the metformin-treated T98G cells were higher than those in the control cells. Metformin induced apoptosis in the T98G cell line in a concentration-dependent manner. Metformin may provide an important contribution to the treatment of glioblastoma multiforme.
Experimental and therapeutic medicine 05/2014; 7(5):1285-1290. DOI:10.3892/etm.2014.1597 · 1.27 Impact Factor
"Type 2 diabetes is a major health problem reaching epidemic proportions in developed countries, and its incidence is rapidly increasing in developing countries as well (1). It is a significant cause of mortality and is strongly associated with an increase in the risk of cardiovascular disease and cancer (2,3). Extensive research has shown that such clinical complications of type 2 diabetes could be attributed, in part, to low-grade chronic inflammation (4,5). "
[Show abstract][Hide abstract] ABSTRACT: Obesity and type 2 diabetes are emerging global epidemics associated with chronic, low-grade inflammation. A characteristic feature of type 2 diabetes is delayed wound healing, which increases the risk of recurrent infections, tissue necrosis, and limb amputation. In health, inflammation is actively resolved by endogenous mediators, such as the resolvins. d-Series resolvins are generated from docosahexaenoic acid (DHA) and promote macrophage-mediated clearance of microbes and apoptotic cells. However, it is not clear how type 2 diabetes affects the resolution of inflammation. Here, we report that resolution of acute peritonitis is delayed in obese diabetic (db/db) mice. Altered resolution was associated with decreased apoptotic cell and Fc receptor-mediated macrophage clearance. Treatment with resolvin D1 (RvD1) enhanced resolution of peritonitis, decreased accumulation of apoptotic thymocytes in diabetic mice, and stimulated diabetic macrophage phagocytosis. Conversion of DHA to monohydroxydocosanoids, markers of resolvin biosynthesis, was attenuated in diabetic wounds, and local application of RvD1 accelerated wound closure and decreased accumulation of apoptotic cells and macrophages in the wounds. These findings support the notion that diabetes impairs resolution of wound healing and demonstrate that stimulating resolution with proresolving lipid mediators could be a novel approach to treating chronic, nonhealing wounds in patients with diabetes.
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