Fatty acid synthase inhibitor orlistat impairs cell growth and down-regulates PD-L1 expression of a human T-cell leukemia line.

Fatty Acid Synthase (FASN) is responsible for the de novo synthesis of fatty acids, which are involved in the preservation of biological membrane structure, energy storage and assembly of factors involved in signal transduction. FASN plays a critical role in supporting tumor cell growth, thus representing a potential target for anti-cancer therapies. Moreover, this enzyme has been recently associated with increased PD-L1 expression, suggesting a role for fatty acids in the impairment of the immune response in the tumor microenvironment. Orlistat, a tetrahydrolipstatin used for the treatment of obesity, has been reported to reduce FASN activity, while inducing a sensible reduction of the growth potential in different cancer models. We have analyzed the effect of orlistat on different features involved in the tumor cell biology of the T-ALL Jurkat cell line. In particular, we have observed that orlistat inhibits Jurkat cell growth and induces a perturbation of cell cycle along with a decline of FASN activity and protein levels. Moreover, the drug produces a remarkable impairment of PD-L1 expression. These findings suggest that orlistat interferes with different mechanisms involved in the control of tumor cell growth and can potentially contribute to decrease the tumor-associated immune-pathogenesis.

Thymoquinone, a bioactive component of Nigella sativa, normalizes insulin secretion from pancreatic ß-cells under glucose overload via regulation of malonyl-CoA.

Thymoquinone (2-isopropyl-5-methylbenzo-1,4-quinone) is a major bioactive component of Nigella sativa, a plant used in traditional medicine to treat a variety of symptoms, including elevated blood glucose levels in type 2 diabetic patients. Normalization of elevated blood glucose depends on both glucose disposal by peripheral tissues and glucose-stimulated insulin secretion (GSIS) from pancreatic ß-cells. We employed clonal ß-cells and rodent islets to investigate the effects of thymoquinone (TQ) and Nigella sativa extracts (NSEs) on GSIS and cataplerotic metabolic pathways implicated in the regulation of GSIS. TQ and NSE regulated NAD(P)H/NAD(P)(+) ratios via a quinone-dependent redox cycling mechanism. TQ content was positively correlated with the degree of redox cycling activity of NSE extracts, suggesting that TQ is a major component engaged in mediating NSE-dependent redox cycling. Both acute and chronic exposure to TQ and NSE enhanced GSIS and were associated with the ability of TQ and NSE to increase the ATP/ADP ratio. Furthermore, TQ ameliorated the impairment of GSIS following chronic exposure of ß-cells to glucose overload. This protective action was associated with the TQ-dependent normalization of chronic accumulation of malonyl-CoA, elevation of acetyl-CoA carboxylase (ACC), fatty acid synthase, and fatty acid-binding proteins following chronic glucose overload. Together, these data suggest that TQ modulates the ß-cell redox circuitry and enhances the sensitivity of ß-cell metabolic pathways to glucose and GSIS under normal conditions as well as under hyperglycemia. This action is associated with the ability of TQ to regulate carbohydrate-to-lipid flux via downregulation of ACC and malonyl-CoA.

Effects of dietary phosphate on glucose and lipid metabolism.

Recent epidemiological and animal studies have suggested that excess intake of phosphate (Pi) is a risk factor for the progression of chronic kidney disease and its cardiovascular complications. However, little is known about the impact of dietary high Pi intake on the development of metabolic disorders such as obesity and type 2 diabetes. In this study, we investigated the effects of dietary Pi on glucose and lipid metabolism in healthy rats. Male 8-wk-old Sprague-Dawley rats were divided into three groups and given experimental diets containing varying amounts of Pi, i.e., 0.2 [low Pi(LP)], 0.6 [control Pi(CP)], and 1.2% [high Pi(HP)]. After 4 wk, the HP group showed lower visceral fat accumulation compared with other groups, accompanied by a low respiratory exchange ratio (V̇CO2/V̇O2) without alteration of locomotive activity. The HP group had lower levels of plasma insulin and nonesterified fatty acids. In addition, the HP group also showed suppressed expression of hepatic lipogenic genes, including sterol regulatory element-binding protein-1c, fatty acid synthase, and acetyl-CoA carboxylase, whereas there was no difference in hepatic fat oxidation among the groups. On the other hand, uncoupling protein (UCP) 1 and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) expression were significantly increased in the brown adipose tissue (BAT) of the HP group. Our data demonstrated that a high-Pi diet can negatively regulate lipid synthesis in the liver and increase mRNA expression related to lipid oxidation and UCP1 in BAT, thereby preventing visceral fat accumulation. Thus, dietary Pi is a novel metabolic regulator.

The effect of early-life stress and chronic high-sucrose diet on metabolic outcomes in female rats.

Early-life stress affects metabolic outcomes and choice of diet influences the development of metabolic disease. Here we tested the hypothesis that chronic sugar intake exacerbates metabolic deficits induced by early-life stress. Early-life stress was induced in Sprague-Dawley rats using limited nesting material in early lactation (LN, postnatal days 2-9), and siblings were given chow alone or with additional sucrose post weaning (n = 9-17 per group). Female control and LN siblings had unlimited access to either chow plus water, or chow and water plus 25% sucrose solution (Sucrose), from 3-15 weeks of age. Weekly body weight and food intake were measured. Glucose and insulin tolerance were tested at 13 and 14 weeks of age, respectively. Rats were killed at 15 weeks. Hepatic triglyceride and markers of lipid synthesis - fatty acid synthase, acetyl-CoA carboxylase alpha and oxidation - and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (Pgc-1α) were examined. Mediators of hepatic glucocorticoid metabolism, specifically 11-beta hydroxysteroid dehydrogenase-1 (11ßHSD-1), 5-α reductase, and glucocorticoid and mineralocorticoid receptor mRNAs were also measured. Sucrose increased caloric intake in both groups, but overall energy intake was not altered by LN exposure. LN exposure had no further impact on sucrose-induced glucose intolerance and increased plasma and liver triglycerides. Hepatic markers of fat synthesis and oxidation were concomitantly activated and 11ßHSD-1 mRNA expression was increased by 53% in LN-Sucrose versus Con-Sucrose rats. Adiposity was increased by 26% in LN-Sucrose versus Con-Sucrose rats. Thus, LN exposure had minimal adverse metabolic effects despite high-sugar diet postweaning.

An easy, rapid and objective mathematical method to identify fatty acid synthase (oncogenic antigen-519) modulators with potential anticancer value.

Fatty acid synthase (FASN) is a novel druggable target for metabolically treating and preventing human malignancies. We envisioned that if loss of sensitivity to C75 (a slow-binding FASN inhibitor) occurs in parallel with loss of FASN expression and/or activity, a mathematical assessment of the nature of the interaction between investigational FASN modulators and C75 may predict the ability of experimental compounds to regulate FASN. We statistically compared the arithmetical sums of the anti-proliferative effects obtained when FASN modulators and C75 were used as single agents to those observed experimentally when agents were actually combined in a sequential schedule (i.e., FASN modulator-->C75). A reduced sensitivity to C75 (antagonism) occurred when compounds down-regulated FASN activity/expression, while an enhanced C75 efficacy (synergism) was found following exposure to FASN up-regulators. This "C75-sensitivity test" might offer an easy, rapid and objective method to identify FASN inhibitors with potential anticancer value in human cancer.