C75 [4-methylene-2-octyl-5-oxo-tetrahydro-furan-3-carboxylic acid] activates carnitine palmitoyltransferase-1 in isolated mitochondria and intact cells without displacement of bound malonyl CoA

Targeting fatty acid uptake and metabolism in cancer cells: A promising strategy for cancer treatment

Despite scientific development, cancer is still a fatal disease. The development of cancer is thought to be significantly influenced by fatty acids. Several mechanisms that control fatty acid absorption and metabolism are reported to be altered in cancer cells to support their survival. Cancer cells can use de novo synthesis or uptake of extracellular fatty acid if one method is restricted. This factor makes it more difficult to target one pathway while failing to treat the disease properly. Side effects may also arise if several inhibitors simultaneously target many targets. If a viable inhibitor could work on several routes, the number of negative effects might be reduced. Comparative investigations against cell viability have found several potent natural and manmade substances. In this review, we discuss the complex roles that fatty acids play in the development of tumors and the progression of cancer, newly discovered and potentially effective natural and synthetic compounds that block the uptake and metabolism of fatty acids, the adverse side effects that can occur when multiple inhibitors are used to treat cancer, and emerging therapeutic approaches.

Perhexiline Demonstrates FYN-mediated Antitumor Activity in Glioblastoma

Glioblastoma is the most common primary malignant brain tumor in adults. Despite aggressive treatment, outcomes remain poor with few long-term survivors. Therefore, considerable effort is being made to identify novel therapies for this malignancy. Targeting tumor metabolism represents a promising therapeutic strategy and activation of fatty acid oxidation (FAO) has been identified as a central metabolic node contributing toward gliomagenesis. Perhexiline is a compound with a long clinical track record in angina treatment and commonly described as an FAO inhibitor. We therefore sought to determine whether this compound might be repurposed to serve as a novel therapy in glioblastoma. Perhexiline demonstrated potent in vitro cytotoxicity, induction of redox stress and apoptosis in a panel of glioblastoma cell lines. However, the antitumor activity of perhexiline was distinct when compared with the established FAO inhibitor etomoxir. By evaluating mitochondrial respiration and lipid dynamics in glioblastoma cells following treatment with perhexiline, we confirmed this compound did not inhibit FAO in our models. Using in silico approaches, we identified FYN as a probable target of perhexiline and validated the role of this protein in perhexiline sensitivity. We extended studies to patient samples, validating the potential of FYN to serve as therapeutic target in glioma. When evaluated in vivo, perhexiline demonstrated the capacity to cross the blood-brain barrier and antitumor activity in both flank and orthotopic glioblastoma models. Collectively, we identified potent FYN-dependent antitumor activity of perhexiline in glioblastoma, thereby, representing a promising agent to be repurposed for the treatment of this devastating malignancy.

In silico investigation of lavandulyl flavonoids for the development of potent fatty acid synthase-inhibitory prototypes

BACKGROUND

Inhibition of fatty acid synthase (FAS) is regarded as a sensible therapeutic strategy for the development of optimal anti-cancer agents. Flavonoids exhibit potent anti-neoplastic properties.

METHODS

The MeOH extract of Sophora flavescens was subjected to chromatographic analyses such as VLC and HPLC for the purification of active flavonoids. The DP4 chemical-shift analysis protocol was employed to investigate the elusive chirality of the lavandulyl moiety of the purified polyphenols. Induced Fit docking protocols and per-residue analyses were utilized to scrutinize structural prerequisites for hampering FAS activity. The FAS-inhibitory activity of the purified flavonoids was assessed via the incorporation of [³H] acetyl-CoA into palmitate.

RESULTS

Six flavonoids, including lavandulyl flavanones, were purified and evaluated for FAS inhibition. The lavandulyl flavanone sophoraflavanone G (2) exhibited the highest potency (IC₅₀ of 6.7±0.2μM), which was more potent than the positive controls. Extensive molecular docking studies revealed the structural requirements for blocking FAS. Per-residue interaction analysis demonstrated that the lavandulyl functional group in the active flavonoids (1-3 and 5) significantly contributed to increasing their binding affinity towards the target enzyme.

CONCLUSION

This research suggests a basis for the in silico design of a lavandulyl flavonoid-based architecture showing anti-cancer effects via enhancement of the binding potential to FAS.

GENERAL SIGNIFICANCE

FAS inhibition by flavonoids and their derivatives may offer significant potential as an approach to lower the risk of various cancer diseases and related fatalities. In silico technologies with available FAS crystal structures may be of significant use in optimizing preliminary leads.

Chemopreventive Metabolites Are Correlated with a Change in Intestinal Microbiota Measured in A-T Mice and Decreased Carcinogenesis

Intestinal microbiota play a significant role in nutrient metabolism, modulation of the immune system, obesity, and possibly in carcinogenesis, although the underlying mechanisms resulting in disease or impacts on longevity caused by different intestinal microbiota are mostly unknown. Herein we use isogenic Atm-deficient and wild type mice as models to interrogate changes in the metabolic profiles of urine and feces of these mice, which are differing in their intestinal microbiota. Using high resolution mass spectrometry approach we show that the composition of intestinal microbiota modulates specific metabolic perturbations resulting in a possible alleviation of a glycolytic phenotype. Metabolites including 3-methylbutyrolactone, kyneurenic acid and 3-methyladenine known to be onco-protective are elevated in Atm-deficient and wild type mice with restricted intestinal microbiota. Thus our approach has broad applicability to study the direct influence of gut microbiome on host metabolism and resultant phenotype. These results for the first time suggest a possible correlation of metabolic alterations and carcinogenesis, modulated by intestinal microbiota in A-T mice.

Increasing fatty acid oxidation remodels the hypothalamic neurometabolome to mitigate stress and inflammation

Modification of hypothalamic fatty acid (FA) metabolism can improve energy homeostasis and prevent hyperphagia and excessive weight gain in diet-induced obesity (DIO) from a diet high in saturated fatty acids. We have shown previously that C75, a stimulator of carnitine palmitoyl transferase-1 (CPT-1) and fatty acid oxidation (FAOx), exerts at least some of its hypophagic effects via neuronal mechanisms in the hypothalamus. In the present work, we characterized the effects of C75 and another anorexigenic compound, the glycerol-3-phosphate acyltransferase (GPAT) inhibitor FSG67, on FA metabolism, metabolomics profiles, and metabolic stress responses in cultured hypothalamic neurons and hypothalamic neuronal cell lines during lipid excess with palmitate. Both compounds enhanced palmitate oxidation, increased ATP, and inactivated AMP-activated protein kinase (AMPK) in hypothalamic neurons in vitro. Lipidomics and untargeted metabolomics revealed that enhanced catabolism of FA decreased palmitate availability and prevented the production of fatty acylglycerols, ceramides, and cholesterol esters, lipids that are associated with lipotoxicity-provoked metabolic stress. This improved metabolic signature was accompanied by increased levels of reactive oxygen species (ROS), and yet favorable changes in oxidative stress, overt ER stress, and inflammation. We propose that enhancing FAOx in hypothalamic neurons exposed to excess lipids promotes metabolic remodeling that reduces local inflammatory and cell stress responses. This shift would restore mitochondrial function such that increased FAOx can produce hypothalamic neuronal ATP and lead to decreased food intake and body weight to improve systemic metabolism.

New synthetic inhibitors of fatty acid synthase with anticancer activity

Fatty acid synthase (FASN) is a lipogenic enzyme that is highly expressed in different human cancers. Here we report the development of a new series of polyphenolic compounds 5-30 that have been evaluated for their cytotoxic capacity in SK-Br3 cells, a human breast cancer cell line with high FASN expression. The compounds with an IC(50) < 50 μM have been tested for their ability to inhibit FASN activity. Among them, derivative 30 blocks the 90% of FASN activity at low concentration (4 μM), is highly cytotoxic in a broad panel of tumor cells, induces apoptosis, and blocks the activation of HER2, AKT, and ERK pathways. Remarkably, 30 does not activate carnitine palmitoyltransferase-1 (CPT-1) nor induces in mice weight loss, which are the main drawbacks of other previously described FASN inhibitors. Thus, FASN inhibitor 30 may aid the validation of this enzyme as a therapeutic target for the treatment of cancer.

Fatty acid oxidation and meiotic resumption in mouse oocytes

We have examined the potential role of fatty acid oxidation (FAO) in AMP-activated protein kinase (AMPK)-induced meiotic maturation. Etomoxir and malonyl CoA, two inhibitors of carnitine palmitoyl transferase-1 (CPT1), and thus FAO, blocked meiotic induction in dbcAMP-arrested cumulus cell-enclosed oocytes (CEO) and denuded oocytes (DO) by the AMPK activator, AICAR. C75, an activator of CPT1 and FAO, stimulated meiotic resumption in CEO and DO. This effect was insensitive to the AMPK inhibitor, compound C, indicating an action downstream of AMPK. Palmitic acid or carnitine also promoted meiotic resumption in DO in the presence of AICAR. Since C75 also suppresses the activity of fatty acid synthase (FAS), we tested another FAS inhibitor, cerulenin. Cerulenin stimulated maturation in arrested oocytes, but to a lesser extent, exhibited significantly slower kinetics and was effective in CEO but not DO. Moreover, etomoxir completely blocked C75-induced maturation but was ineffective in cerulenin-treated oocytes, suggesting that the meiosis-inducing action of C75 is through activation of FAO within the oocyte, while that of cerulenin is independent of FAO and acts within the cumulus cells. Finally, we determined that long chain, but not short chain, fatty acyl carnitine derivatives were stimulatory to oocyte maturation. Palmitoyl carnitine stimulated maturation in both CEO and DO, with rapid kinetics in DO; this effect was blocked by mercaptoacetate, a downstream inhibitor of FAO. These results indicate that activation of AMPK stimulates meiotic resumption in mouse oocytes by eliminating a block to FAO.

Structural insight into function and regulation of carnitine palmitoyltransferase

The control of fatty acid translocation across the mitochondrial membrane is mediated by the carnitine palmitoyltransferase (CPT) system. Modulation of its functionality has simultaneous effects on fatty acid and glucose metabolism. This encourages use of the CPT system as drug target for reduction of gluconeogenesis and restoration of lipid homeostasis, which are beneficial in the treatment of type 2 diabetes mellitus and obesity. Recently, crystal structures of CPT-2 were determined in uninhibited forms and in complexes with inhibitory substrate-analogs with anti-diabetic properties in animal models and in clinical studies. The CPT-2 crystal structures have advanced understanding of CPT structure-function relationships and will facilitate discovery of novel inhibitors by structure-based drug design. However, a number of unresolved questions regarding the biochemistry and pharmacology of CPT enzymes remain and are addressed in this review.

Fatty acid synthase activity in tumor cells

While normal tissues are tightly regulated by nutrition and a carefully balanced system of glycolysis and fatty acid synthesis, tumor cells are under significant evolutionary pressure to bypass many of the checks and balances afforded normally. Cancer cells have high energy expenditure from heightened proliferation and metabolism and often show increased lipogenesis. Fatty acid synthase (FASN), the enzyme responsible for catalyzing the ultimate steps of fatty acid synthesis in cells, is expressed at high levels in tumor cells and is mostly absent in corresponding normal cells. Because of the unique expression profile of FASN, there is considerable interest not only in understanding its contribution to tumor cell growth and proliferation, but also in developing inhibitors that target FASN specifically as an anti-tumor modality. Pharmacological blockade of FASN activity has identified a pleiotropic role for FASN in mediating aspects of proliferation, growth and survival. As a result, a clearer understanding of the role of FASN in tumor cells has been developed.

Discovery of GSK837149A, an inhibitor of human fatty acid synthase targeting the beta-ketoacyl reductase reaction

GSK837149A has been identified as a selective inhibitor of human fatty acid synthase (FAS). The compound was first isolated as a minor impurity in a sample found to be active against the enzyme in a high-throughput screening campaign. The structure of this compound was confirmed by NMR and MS studies, and evaluation of the newly synthesized molecule confirmed its activity against FAS. The compound and other analogs synthesized, all being symmetrical structures containing a bisulfonamide urea, act by inhibiting the beta-ketoacyl reductase activity of the enzyme. GSK837149A inhibits FAS in a reversible mode, with a K(i) value of approximately 30 nm, and it possibly binds to the enzyme-ketoacyl-ACP complex. Although initial results suggest that cell penetration for these compounds is impaired, they still can be regarded as useful tools with which to probe and explore the beta-ketoacyl reductase active site in FAS, helping in the design of new inhibitors.

Pharmacological stimulation of brain carnitine palmitoyl-transferase-1 decreases food intake and body weight

Inhibition of brain carnitine palmitoyl-transferase-1 (CPT-1) is reported to decrease food intake and body weight in rats. Yet, the fatty acid synthase (FAS) inhibitor and CPT-1 stimulator C75 produces hypophagia and weight loss when given to rodents intracerebroventricularly (icv). Thus roles and relative contributions of altered brain CPT-1 activity and fatty acid oxidation in these phenomena remain unclarified. We administered compounds that target FAS or CPT-1 to mice by single icv bolus and examined acute and prolonged effects on feeding and body weight. C75 decreased food intake rapidly and potently at all doses (1-56 nmol) and dose dependently inhibited intake on day 1. Dose-dependent weight loss on day 1 persisted through 4 days of postinjection monitoring. The FAS inhibitor cerulenin produced dose-dependent (560 nmol) hypophagia for 1 day, weight loss for 2 days, and weight regain to vehicle control by day 3. The CPT-1 inhibitor etomoxir (32, 320 nmol) did not alter overall day 1 feeding. However, etomoxir attenuated the hypophagia produced by C75, indicating that CPT-1 stimulation is important for C75's effect. A novel compound, C89b, was characterized in vitro as a selective stimulator of CPT-1 that does not affect fatty acid synthesis. C89b (100, 320 nmol) decreased feeding in mice for 3 days and produced persistent weight loss for 6 days without producing conditioned taste aversion. Similarly, intraperitoneal administration decreased feeding and body weight without producing conditioned taste aversion. These results suggest a role for brain CPT-1 in the regulation of energy balance and implicate CPT-1 stimulation as a pharmacological approach to weight loss.

Fatty acid synthase inhibition activates AMP-activated protein kinase in SKOV3 human ovarian cancer cells

Fatty acid synthase (FAS), the enzyme responsible for the de novo synthesis of fatty acids, is highly expressed in ovarian cancers and most common human carcinomas. Inhibition of FAS and activation of AMP-activated protein kinase (AMPK) have been shown to be cytotoxic to human cancer cells in vitro and in vivo. In this report, we explore the cytotoxic mechanism of action of FAS inhibition and show that C93, a synthetic FAS inhibitor, increases the AMP/ATP ratio, activating AMPK in SKOV3 human ovarian cancer cells, which leads to cytotoxicity. As a physiologic consequence of AMPK activation, acetyl-CoA carboxylase (ACC), the rate-limiting enzyme of fatty acid synthesis, was phosphorylated and inhibited whereas glucose oxidation was increased. Despite these attempts to conserve energy, the AMP/ATP ratio increased with worsening cellular redox status. Pretreatment of SKOV3 cells with compound C, an AMPK inhibitor, substantially rescued the cells from C93 cytotoxicity, indicating its dependence on AMPK activation. 5-(Tetradecyloxy)-2-furoic acid, an ACC inhibitor, did not activate AMPK despite inhibiting fatty acid synthesis pathway activity and was not significantly cytotoxic to SKOV3 cells. This indicates that substrate accumulation from FAS inhibition triggering AMPK activation, not end-product depletion of fatty acids, is likely responsible for AMPK activation. C93 also exhibited significant antitumor activity and apoptosis against SKOV3 xenografts in athymic mice without significant weight loss or cytotoxicity to proliferating cellular compartments such as bone marrow, gastrointestinal tract, or skin. Thus, pharmacologic FAS inhibition selectively activates AMPK in ovarian cancer cells, inducing cytotoxicity while sparing most normal human tissues from the pleiotropic effects of AMPK activation.

The role of hypothalamic malonyl-CoA in energy homeostasis

Energy balance is monitored by hypothalamic neurons that respond to peripheral hormonal and afferent neural signals that sense energy status. Recent physiologic, pharmacologic, and genetic evidence has implicated malonyl-CoA, an intermediate in fatty acid synthesis, as a regulatory component of this energy-sensing system. The level of malonyl-CoA in the hypothalamus is dynamically regulated by fasting and feeding, which alter subsequent feeding behavior. Fatty acid synthase (FAS) inhibitors, administered systemically or intracerebroventricularly to lean or obese mice, increase hypothalamic malonyl-CoA leading to the suppression of food intake. Conversely, lowering malonyl-CoA with an acetyl-CoA carboxylase (ACC) inhibitor or by the ectopic expression of malonyl-CoA decarboxylase in the hypothalamus increases food intake and reverses inhibition by FAS inhibitors. Physiologically, the level of hypothalamic malonyl-CoA appears to be determined through phosphorylation/dephosphorylation of ACC by AMP kinase in response to changes in the AMP/ATP ratio, an indicator of energy status. Recent evidence suggests that the brain-specific carnitine:palmitoyl-CoA transferase-1 (CPT1c) may be a regulated target of malonyl-CoA that relays the "malonyl-CoA signal" in hypothalamic neurons that express the orexigenic and anorexigenic neuropeptides that regulate food intake and peripheral energy expenditure. Together these findings support a role for malonyl-CoA as an intermediary in the control of energy homeostasis.

Fatty acid metabolism, the central nervous system, and feeding

A potential role for fatty acid metabolism in the regulation of energy balance in the brain or in the periphery has been considered only recently. Fatty acid synthase (FAS) catalyzes the synthesis of long-chain fatty acids, whereas the breakdown of fatty acids by beta-oxidation is regulated by carnitine palmitoyltransferase-1, the rate-limiting enzyme for the entry of fatty acids into the mitochondria for oxidation. While the question of the physiological role of fatty acid metabolism remains to be resolved, studies indicate that inhibition of FAS or stimulation of carnitine palmitoyltransferase-1 using cerulenin or synthetic FAS inhibitors reduces food intake and incurs profound and reversible weight loss. Several hypotheses regarding the mechanisms by which these small molecules mediate their effects have been entertained. Centrally, these compounds alter the expression of hypothalamic neuropeptides, generally reducing the expression of orexigenic peptides. Whether through central, peripheral, or combined central and peripheral mechanisms, these compounds also increase energy consumption to augment weight loss. In vitro and in vivo studies indicate that at least part of C75's effects is mediated by modulation of adenosine monophosphate-activated protein kinase, a member of an energy-sensing kinase family. These compounds, with chronic treatment, also alter gene expression peripherally to favor a state of enhanced energy consumption. Together, these effects raise the possibility that pharmacological alterations in fatty acid synthesis/degradation may serve as a target for obesity therapeutics.

Increased lipogenesis in cancer cells: new players, novel targets

PURPOSE OF REVIEW

This review evaluates recent findings on the mechanisms by which lipogenic enzymes are upregulated or activated in cancer cells, the implications of increased lipogenesis for cancer cell biology and the feasibility of exploiting this pathway and its regulators as targets for antineoplastic intervention.

RECENT FINDINGS

The list of cancer types showing increased lipogenic enzyme expression keeps growing and further evidence is accumulating that growth factor signaling and particularly activation of the phosphatidylinositol 3'-kinase/protein kinase B pathway plays a role in this process. This signaling pathway stimulates lipogenic gene transcription through activation of the lipogenic transcription factor sterol regulatory element-binding protein-1 and directly activates lipogenic enzymes such as ATP-citrate lyase, linking the upregulation of lipogenesis in cancer cells to the well known tumor-associated increase in glycolysis. Steroid hormones, overexpression of the ubiquitin-specific protease-2a and mutations in breast cancer susceptibility gene 1 may further enhance lipid synthesis. While fatty acid synthase is further established as a target for antineoplastic intervention, recent findings show that interference with acetyl-CoA carboxylase-alpha, ATP citrate lyase or the AMP-activated protein kinase limits cancer cell proliferation and survival.

SUMMARY

The same disturbances in signaling pathways responsible for oncogenic transformation may also contribute to the increased lipogenesis observed in tumor cells. Increased lipogenesis involves modulation of multiple lipogenic enzymes at both transcriptional and posttranscriptional level and is linked to other cancer-associated metabolic changes. Not only fatty acid synthase, but in fact all key enzymes involved in fatty acid synthesis as well as key metabolic regulators are potential targets for antineoplastic intervention.

Treating the metabolic syndrome: acetyl-CoA carboxylase inhibition

Metabolic syndrome is defined as a clustering of cardiovascular risk factors (abdominal obesity, hyperinsulinaemia, atherogenic dislipidaemia, hypertension, hypercoagulability) that together increase the risk of developing coronary heart disease and Type-2 diabetes. Inhibition of acetyl-CoA carboxylase (ACC), with its resultant inhibition of fatty acid synthesis and stimulation of fatty acid oxidation, has the potential to favourably affect, in a concerted manner, a multitude of cardiovascular risk factors associated with metabolic syndrome. Studies in ACC2 knockout mice and in experimental animals treated with isozyme-nonselective ACC inhibitors have demonstrated the potential for treating metabolic syndrome through this modality. A variety of structurally diverse, mechanistically distinct classes of ACC inhibitors have been disclosed in the scientific and patent literature. Isozyme-nonselective ACC inhibitors may provide the optimal therapeutic potential for beneficially affecting metabolic syndrome. However, demonstration of the full potential of isozyme-selective inhibitors, once identified, should reveal advantages and liabilities associated with single isozyme inhibition. Whereas demonstrating clinical efficacy of an ACC inhibitor should be straightforward, the heterogeneity of the patient population and absence of established guidelines regarding approval end points for agents simultaneously affecting multiple aspects of metabolic syndrome will pose developmental challenges for initial market entries.

Novel effect of C75 on carnitine palmitoyltransferase I activity and palmitate oxidation

C75 is a potential drug for the treatment of obesity. It was first identified as a competitive, irreversible inhibitor of fatty acid synthase (FAS). It has also been described as a malonyl-CoA analogue that antagonizes the allosteric inhibitory effect of malonyl-CoA on carnitine palmitoyltransferase I (CPT I), the main regulatory enzyme involved in fatty acid oxidation. On the basis of MALDI-TOF analysis, we now provide evidence that C75 can be transformed to its C75-CoA derivative. Unlike the activation produced by C75, the CoA derivative is a potent competitive inhibitor that binds tightly but reversibly to CPT I. IC50 values for yeast-overexpressed L- or M-CPT I isoforms, as well as for purified mitochondria from rat liver and muscle, were within the same range as those observed for etomoxiryl-CoA, a potent inhibitor of CPT I. When a pancreatic INS(823/13), muscle L6E9, or kidney HEK293 cell line was incubated directly with C75, fatty acid oxidation was inhibited. This suggests that C75 could be transformed in the cell to its C75-CoA derivative, inhibiting CPT I activity and consequently fatty acid oxidation. In vivo, a single intraperitoneal injection of C75 in mice produced short-term inhibition of CPT I activity in mitochondria from the liver, soleus, and pancreas, indicating that C75 could be transformed to its C75-CoA derivative in these tissues. Finally, in silico molecular docking studies showed that C75-CoA occupies the same pocket in CPT I as palmitoyl-CoA, suggesting an inhibiting mechanism based on mutual exclusion. Overall, our results describe a novel role for C75 in CPT I activity, highlighting the inhibitory effect of its C75-CoA derivative.

Effects of Oleic Acid on Distinct Populations of Neurons in the Hypothalamic Arcuate Nucleus Are Dependent on Extracellular Glucose Levels

Pharmacological manipulation of fatty acid metabolism in the hypothalamic arcuate nucleus (ARC) alters energy balance and glucose homeostasis. Thus, we tested the hypotheses that distinctive populations of ARC neurons are oleic acid (OA) sensors that exhibit a glucose dependency, independent of whether some of these OA sensors are also glucose-sensing neurons. We used patch-clamp recordings to investigate the effects of OA on ARC neurons in brain slices from 14- to 21-day-old Sprague–Dawley (SD) rats. Additionally, we recorded spontaneous discharge rate in ARC neurons in 8-wk-old fed and fasted SD rats in vivo. Patch-clamp studies showed that in 2.5 mM glucose 12 of 94 (13%) ARC neurons were excited by 2 μM OA (OA-excited or OAE neurons), whereas six of 94 (6%) were inhibited (OA-inhibited2.5or OAI2.5neurons). In contrast, in 0.1 mM glucose, OA inhibited six of 20 (30%) ARC neurons (OAI0.1neurons); none was excited. None of the OAI0.1neurons responded to OA in 2.5 mM glucose. Thus OAI2.5and OAI0.1neurons are distinct. Similarly, in seven of 20 fed rats (35%) the overall response was OAE-like, whereas in three of 20 (15%) it was OAI-like. In contrast, in fasted rats only OAI-like response were observed (three of 15; 20%). There was minimal overlap between OA-sensing neurons and glucose-sensing neurons. In conclusion, OA regulated three distinct subpopulations of ARC neurons in a glucose-dependent fashion. These data suggest that an interaction between glucose and fatty acids regulates OA sensing in ARC neurons.

The connections between C75 and obesity drug-target pathways

Obesity and its attendant disorders, such as Type II diabetes, have reached epidemic proportions in the USA, and their prevalence is increasing globally. C75 is a small-molecule inhibitor of fatty acid synthase (FAS) and a stimulator of carnitine palmitoyl 1 activity, which causes profound weight loss in mice. Although C75 is not a compound that is destined for human drug development, it has provided two potential pathways to target in obesity therapy: fatty acid synthesis and fatty acid oxidation. In this article, we discuss the latest data challenging the relationship between fatty acid synthase inhibition and C75-induced anorexia.