Metformin May Alter the Metabolic Reprogramming in Cancer Cells by Disrupting the L-Arginine Metabolism: A Preliminary Computational Study

Metabolic reprogramming in cancer is considered to be one of the most important hallmarks to drive proliferation, angiogenesis, and invasion. AMP-activated protein kinase activation is one of the established mechanisms for metformin’s anti-cancer actions. However, it has been suggested that metformin may exert antitumoral effects by the modulation of other master regulators of cellular energy. Here, based on structural and physicochemical criteria, we tested the hypothesis that metformin may act as an antagonist of L-arginine metabolism and other related metabolic pathways. First, we created a database containing different L-arginine-related metabolites and biguanides. After that, comparisons of structural and physicochemical properties were performed employing different cheminformatic tools. Finally, we performed molecular docking simulations using AutoDock 4.2 to compare the affinities and binding modes of biguanides and L-arginine-related metabolites against their corresponding targets. Our results showed that biguanides, especially metformin and buformin, exhibited a moderate-to-high similarity to the metabolites belonging to the urea cycle, polyamine metabolism, and creatine biosynthesis. The predicted affinities and binding modes for biguanides displayed good concordance with those obtained for some L-arginine-related metabolites, including L-arginine and creatine. In conclusion, metabolic reprogramming in cancer cells by metformin and biguanides may be also driven by metabolic disruption of L-arginine and structurally related compounds.

Effect of buformin on splanchnic carbohydrate and substrate metabolism in healthy man

The effect of buformin (100 mg b.i.d. for 5 days) on carbohydrate metabolism, both splanchnic glucose output (SGO) and net substrate exchange were studied in 6 healthy male volunteers in the basal state and following glucose ingestion (100 g). Control studies without buformin were also performed in 5 men. Splanchnic glucose and substrate exchange was determined by means of the hepatic venous catheter technique. SGO was 154 +/- 18 (SEM) mg/min in the postabsorptive state and increased 33.3 +/- 2.8 g above the basal level during the 150 min period following glucose ingestion. Buformin administration did not alter basal SGO (157 +/- 26 mg/min), nor the splanchnic exchange of pyruvate, alanine, glycerol, OH-butyrate and acetoacetate. Splanchnic lactate balance was altered by buformin and net lactate output occurred. Following glucose ingestion the rise in splanchnic lactate output was increased, whereas no change in SGO (32.9 +/- 3.5 g/150 min) and splanchnic exchange of the other substrates was observed. The increase in arterial blood glucose concentration following oral glucose loading was reduced by buformin pretreatment (p less than 0.005). The insulin production rate (basal, 16 +/- 2 mU/min; following oral glucose, 13 +/- 2 U/150 min) as calculated from C-peptide release from the splanchnic area was unchanged by buformin. Except for a marked rise in splanchnic lactate production, buformin did not alter splanchnic carbohydrate metabolism after orally ingested glucose in healthy man. The diminished increase in arterial blood glucose concentration associated with unaltered insulin production suggests that buformin facilitates glucose utilization by peripheral tissues.