5-(Tetradecyloxy)-2-furoic acid

Targeting MYC induces lipid droplet accumulation by upregulation of HILPDA in clear cell renal cell carcinoma

Metabolic reprogramming is critical during clear cell renal cell carcinoma (ccRCC) tumorigenesis, manifested by accumulation of lipid droplets (LDs), organelles that have emerged as new hallmarks of cancer. Yet, regulation of their biogenesis is still poorly understood. Here, we demonstrate that MYC inhibition in ccRCC cells lacking the von Hippel Lindau (VHL) gene leads to increased triglyceride content potentiating LD formation in a glutamine-dependent manner. Importantly, the concurrent inhibition of MYC signaling and glutamine metabolism prevented LD accumulation and reduced tumor burden in vivo. Furthermore, we identified the hypoxia-inducible lipid droplet-associated protein (HILPDA) as the key driver for induction of MYC-driven LD accumulation and demonstrated that conversely, proliferation, LD formation, and tumor growth are impaired upon its downregulation. Finally, analysis of ccRCC tissue as well as healthy renal control samples postulated HILPDA as a specific ccRCC biomarker. Together, these results provide an attractive approach for development of alternative therapeutic interventions for the treatment of this type of renal cancer.

Effects of in vivo phlorizin treatment and in vitro addition of carnitine, propionate, acetate, and 5-tetradecyloxy-2-furoic acid on palmitate metabolism in ovine hepatocytes

Modulatory effects of l-carnitine, acetate, propionate, and 5-tetradecyloxy-2-furoic acid (TOFA; an inhibitor of acetyl-CoA carboxylase) on oxidation and esterification of [1-¹⁴C]-palmitate were studied in hepatocytes isolated from phlorizin-treated and control wethers. Our hypotheses were that (1) palmitate oxidation would be greater in hepatocytes from sheep injected with phlorizin; (2) l-carnitine would increase palmitate oxidation more in hepatocytes from sheep injected with phlorizin; and (3) acetate and propionate would decrease oxidation in sheep hepatocytes partly through action of acetyl-CoA carboxylase. Palmitate metabolism did not differ between cells from control and those from phlorizin-treated wethers. Carnitine increased oxidation of palmitate to CO₂ and acid-soluble products (ASP; mainly ketone bodies) and decreased esterification of palmitate in isolated hepatocytes from both groups of wethers, but the increase in oxidation to ASP was greater in cells from phlorizin-treated wethers. Propionate increased palmitate oxidation to CO₂ in phlorizin-treated wethers. Propionate increased oxidation of palmitate to ASP in control wethers but decreased oxidation to ASP in phlorizin-treated wethers. Propionate increased esterification of palmitate to total esterified products and triglyceride, and the effect was larger in phlorizin-treated wethers. Acetate decreased palmitate esterification to total esterified products in control wethers, but the effect was blunted in phlorizin-treated wethers. Acetate did not affect palmitate oxidation. Addition of TOFA increased production of triglyceride from palmitate in the presence of propionate. The lack of interaction between TOFA and propionate indicates that propionate does not inhibit carnitine palmitoyltransferase I via cytosolic generation of methylmalonyl-CoA by acetyl-CoA carboxylase. In conclusion, although in vivo phlorizin treatment did not affect in vitro metabolism of palmitate by isolated ovine hepatocytes, phlorizin increased the stimulatory effect of carnitine on oxidation of palmitate to ASP and the inhibitory effect of propionate on oxidation of palmitate to ASP. Metabolism of acetate and propionate by acetyl-CoA carboxylase did not affect palmitate oxidation or esterification. Results provide additional insight into control of fatty acid metabolism in hepatocytes.

Acetyl-CoA carboxylase (ACC) as a therapeutic target for metabolic syndrome and recent developments in ACC1/2 inhibitors

Introduction: Acetyl-CoA Carboxylase (ACC) is an essential rate-limiting enzyme in fatty acid metabolism. For many years, ACC inhibitors have gained great attention for developing therapeutics for various human diseases including microbial infections, metabolic syndrome, obesity, diabetes, and cancer. Areas covered: We present a comprehensive review and update of ACC inhibitors. We look at the current advance of ACC inhibitors in clinical studies and the implications in drug discovery. We searched ScienceDirect ( https://www.sciencedirect.com/ ), ACS ( https://pubs.acs.org/ ), Wiley ( https://onlinelibrary.wiley.com/ ), NCBI ( https://www.ncbi.nlm.nih.gov/ ) and World Health Organization ( https://www.who.int/ ). The keywords used were Acetyl-CoA Carboxylase, lipid, inhibitors and metabolic syndrome. All documents were published before June 2019. Expert opinion: The key regulatory role of ACC in fatty acid synthesis and oxidation pathways makes it an attractive target for various metabolic diseases. In particular, the combination of ACC inhibitors with other drugs is a new strategy for the treatment of nonalcoholic fatty liver disease and nonalcoholic steatohepatitis. Expanding the clinical indications for ACC inhibitors will be one of the hot directions in the future. It is also worth looking forward to exploring safe and efficient inhibitors that act on the BC domain of ACC.

Nonesterified fatty acid accumulation and release during heart muscle-cell (myocyte) injury: modulation by extracellular "acceptor"

Long-chain nonesterified fatty acid (NEFA) accumulation in the heart muscle cell (myocyte) and NEFA release to the extracellular milieu are considered contributors to the pathogenesis of myocardial injury in a number of cardiovascular disease states. Reported here is a study of the factors which influence and control the interactions among NEFA formation, intracellular NEFA accumulation, and NEFA release to the extracellular compartment by the irreversibly injured myocyte. Under conditions of metabolic inhibition, neonatal rat myocytes in primary monolayer culture became virtually depleted of ATP within 8 h. The metabolically inhibited myocytes evidenced membrane phospholipid degradation and a resultant net accumulation of NEFA produced thereby in the extracellular medium. However, under conditions of nutrient deprivation, the injured myocytes retained the NEFA produced from phospholipid catabolism intracellularly and did not release it to the culture medium, although the extent of myocyte ATP depletion was the same as it had been from metabolic inhibition. Serum could elicit, in a concentration-dependent fashion, the quantitative release of NEFA from metabolically inhibited myocytes to the culture medium but did not influence the net production of NEFA by the injured cells. Similarly, NEFA release from nutrient-deprived myocytes incubated in serum-free, substrate-free medium or in physiological buffer could be induced by supplementing the medium or buffer with bovine serum albumin (BSA), and the extent of NEFA release, but not NEFA formation, was dependent upon the extracellular BSA concentration. No manipulations to media other than changing their serum content or supplementing them with BSA were found to influence the disposition of NEFA produced during phospholipid catabolism in the irreversibly injured, ATP-depleted myocyte. Therefore, although progressive metabolic compromise in the myocyte was correlated with increasing, net NEFA formation, the distribution of the NEFA between the intracellular and the extracellular compartments was not determined by the magnitude of ATP loss or by the nature or duration of at least two injury stimuli, metabolic inhibition and nutrient deprivation. Rather, the net release of NEFA from the ATP-depleted myocyte to the culture medium and the consequent reduction of intracellular myocyte NEFA overload were critically and causally dependent upon the presence and concentration of extracellular NEFA "acceptor". The influence of acceptor on the mobilization of NEFA from the injured myocyte has implications regarding the use of NEFA release as an index of myocyte pathology and could serve to modify the progression and extent of myocardial injury in vivo.

Amphiphile-induced heart muscle-cell (myocyte) injury: effects of intracellular fatty acid overload

Lipid amphiphile toxicity may be an important contributor to myocardial injury, especially during ischemia/reperfusion. In order to investigate directly the potential biochemical and metabolic effects of amphiphile overload on the functioning heart muscle cell (myocyte), a novel model of nonesterified fatty acid (NEFA)-induced myocyte damage has been defined. The model uses intact, beating neonatal rat myocytes in primary monolayer culture as a study object and 5-(tetradecyloxy)-2-furoic acid (TOFA) as a nonmetabolizable fatty acid. Myocytes incubated with TOFA accumulated it as NEFA, and the consequent NEFA amphiphile overload elicited a variety of cellular defects (including decreased beating rate, depletion of high-energy stores and glycogen pools, and breakdown of myocyte membrane phospholipid) and culminated in cell death. The amphiphile-induced cellular pathology could be reversed by removing TOFA from the culture medium, which resulted in intracellular TOFA "wash-out." Although the development and severity of amphiphile-induced myocyte injury could be correlated with both the intracellular TOFA/NEFA content (i.e., the level of TOFA to which the cells were exposed) and the duration of this exposure, removal of amphiphile overload did not inevitably lead to myocyte recovery. TOFA had adverse effects on myocyte mitochondrial function in situ (decoupling of oxidative phosphorylation, impairing respiratory control) and on myocyte oxidative catabolism (transiently increasing fatty acid beta oxidation, citric acid cycle flux, and glucose oxidation). The amphiphile-induced bioenergetic abnormalities appeared to constitute a state of "metabolic anoxia" underlying the progression of myocyte injury to cell death. This anoxic state could be ameliorated to some extent, but not prevented, by carbohydrate catabolism.