Tumor cell proliferation and migration processes are regulated by multiple metabolic pathways including glycolysis and de novo lipogenesis. Since acetyl-CoA carboxylase (ACC) is at the junction of ...lipids synthesis and oxidative metabolic pathways, we investigated whether use of a dual ACC inhibitor would provide a potential therapy against certain lipogenic cancers. The impact of dual ACC1/ACC2 inhibition was investigated using a dual ACC1/ACC2 inhibitor as well as dual siRNA knock down on the cellular viability and metabolism of two glioblastoma multiform cancer cell lines, U87 and a more aggressive form, U87 EGFRvIII. We first demonstrated that while ACCi inhibited DNL in both cell lines, ACCi preferentially blunted the U87 EGFRvIII cellular proliferation capacity. Metabolically, chronic treatment with ACCi significantly upregulated U87 EGFRvIII cellular respiration and extracellular acidification rate, a marker of glycolytic activity, but impaired mitochondrial health by reducing maximal respiration and decreasing mitochondrial ATP production efficiency. Moreover, ACCi treatment altered the cellular lipids content and increased apoptotic caspase activity in U87 EGFRvIII cells. Collectively these data indicate that ACC inhibition, by reducing DNL and increasing cellular metabolic rate, may have therapeutic utility for the suppression of lipogenic tumor growth and warrants further investigation.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Introduction:
Type 2 diabetes mellitus (T2DM) represents a rapidly expanding healthcare challenge. There is a significant need for novel therapies to help patients achieve and maintain glycemic ...control in order to avoid the long-term microvascular and macrovascular complications associated with the disease. Small molecule allosteric activators of the glucokinase enzyme, an important regulator of glucose homeostasis, have emerged as a potential new class of therapeutics. Glucokinase activators have been shown to effectively lower fasting and postprandial glucose in T2DM patients; however, hypoglycemia emerged as a potential risk limiting their therapeutic potential. To mitigate this risk, recent efforts have focused on the design of liver-specific activators that seek to normalize hepatic glucose uptake and production without potentiating glucose-stimulated insulin secretion.
Areas covered:
The article reviews the various drug discovery strategies that have emerged for the development of candidates that selectively activate glucokinase in the liver. Literature from 2000 to 2012 is surveyed including scientific publications, patent applications, conferences and clinical trials.
Expert opinion:
Liver selective agents have proven to be an effective strategy for mitigating the hypoglycemia risk that has been historically associated with this mechanism. The ultimate therapeutic potential of this approach will depend on the results of longer patient studies which are currently being conducted with several clinical candidates. The discovery of these liver-specific activators has highlighted several challenges in the design of tissue-selective therapeutics, which will need to be overcome in the future.
Alterations in lipid metabolism might contribute to the pathogenesis of non-alcoholic fatty liver disease (NAFLD). However, no pharmacological agents are currently approved in the United States or ...the European Union for the treatment of NAFLD. Two parallel phase 2a studies investigated the effects of liver-directed ACC1/2 inhibition in adults with NAFLD. The first study ( NCT03248882 ) examined the effects of monotherapy with a novel ACC1/2 inhibitor, PF-05221304 (2, 10, 25 and 50 mg once daily (QD)), versus placebo at 16 weeks of treatment; the second study ( NCT03776175 ) investigated the effects of PF-05221304 (15 mg twice daily (BID)) co-administered with a DGAT2 inhibitor, PF-06865571 (300 mg BID), versus placebo after 6 weeks of treatment. The primary endpoint in both studies was percent change from baseline in liver fat assessed by magnetic resonance imaging-proton density fat fraction. Dose-dependent reductions in liver fat reached 50-65% with PF-05221304 monotherapy doses ≥10 mg QD; least squares mean (LSM) 80% confidence interval (CI) was -7.2 (-13.9, 0.0), -17.1 (-22.7, -11.1), -49.9 (-53.3, -46.2), -55.9 (-59.0, -52.4) and -64.8 (-67.5, -62.0) with 16 weeks placebo and PF-05221304 2, 10, 25 and 50 mg QD, respectively. The overall incidence of adverse events (AEs) did not increase with increasing PF-05221304 dose, except for a dose-dependent elevation in serum triglycerides (a known consequence of hepatic acetyl-coenzyme A carboxylase (ACC) inhibition) in 23/305 (8%) patients, leading to withdrawal in 13/305 (4%), and a dose-dependent elevation in other serum lipids. Co-administration of PF-05221304 and PF-06865571 lowered liver fat compared to placebo (placebo-adjusted LSM (90% CI) -44.6% (-54.8, -32.2)). Placebo-adjusted LSM (90% CI) reduction in liver fat was -44.5% (-55.0, -31.7) and -35.4% (-47.4, -20.7) after 6 weeks with PF-05221304 or PF-06865571 alone. AEs were reported for 10/28 (36%) patients after co-administered PF-05221304 and PF-06865571, with no discontinuations due to AEs, and the ACC inhibitor-mediated effect on serum triglycerides was mitigated, suggesting that PF-05221304 and PF-06865571 co-administration has the potential to address some of the limitations of ACC inhibition alone.
PF‐04991532 ((S)‐6‐(3‐Cyclopentyl‐2‐(4‐(trifluoromethyl)‐1H‐imidazol‐1‐yl) propanamido) nicotinic acid) is a glucokinase activator designed to achieve hepato‐selectivity via organic ...anion‐transporting polypeptides (OATP)s, so as to minimize systemic hypoglycemic effects. This study investigated the effect of OATP1B1/1B3 inhibition and renal impairment on PF‐04991532 oral pharmacokinetics. Cyclosporine (600 mg single dose) increased mean area under the plasma curve (AUC) of PF‐04991532 by approximately threefold in healthy subjects. In a renal impairment study, PF‐04991532 AUC values were ~ 2.3‐fold greater in subjects with mild, moderate, and severe kidney dysfunction, compared with healthy subjects. Physiologically‐based pharmacokinetic (PBPK) model parameterizing hepatic and renal transporter‐mediated disposition based on in vitro inputs, and verified using first‐in‐human data, indicated the key role of OATP‐mediated hepatic uptake in the systematic and target‐tissue exposure of PF‐04991532. Mechanistic evaluation of the clinical data suggest reduced hepatic OATPs (~ 35%) and renal organic anion transporter (OAT)3 (80–90%) function with renal impairment. This study illustrates the adequacy and utility of the PBPK approach in assessing the impact of drug interactions and kidney dysfunction on transporter‐mediated disposition.
Hyperglycemia resulting from type 2 diabetes mellitus (T2DM) is the main cause of diabetic complications such as retinopathy and neuropathy. A reduction in hyperglycemia has been shown to prevent ...these associated complications supporting the importance of glucose control. Glucokinase converts glucose to glucose-6-phosphate and determines glucose flux into the β-cells and hepatocytes. Since activation of glucokinase in β-cells is associated with increased risk of hypoglycemia, we hypothesized that selectively activating hepatic glucokinase would reduce fasting and postprandial glucose with minimal risk of hypoglycemia. Previous studies have shown that hepatic glucokinase overexpression is able to restore glucose homeostasis in diabetic models; however, these overexpression experiments have also revealed that excessive increases in hepatic glucokinase activity may also cause hepatosteatosis. Herein we sought to evaluate whether liver specific pharmacological activation of hepatic glucokinase is an effective strategy to reduce hyperglycemia without causing adverse hepatic lipids changes. To test this hypothesis, we evaluated a hepatoselective glucokinase activator, PF-04991532, in Goto-Kakizaki rats. In these studies, PF-04991532 reduced plasma glucose concentrations independent of changes in insulin concentrations in a dose-dependent manner both acutely and after 28 days of sub-chronic treatment. During a hyperglycemic clamp in Goto-Kakizaki rats, the glucose infusion rate was increased approximately 5-fold with PF-04991532. This increase in glucose infusion can be partially attributed to the 60% reduction in endogenous glucose production. While PF-04991532 induced dose-dependent increases in plasma triglyceride concentrations it had no effect on hepatic triglyceride concentrations in Goto-Kakizaki rats. Interestingly, PF-04991532 decreased intracellular AMP concentrations and increased hepatic futile cycling. These data suggest that hepatoselective glucokinase activation may offer glycemic control without inducing hepatic steatosis supporting the evaluation of tissue specific activators in clinical trials.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Recent studies suggest that excess dietary fructose contributes to metabolic dysfunction by promoting insulin resistance, de novo lipogenesis (DNL), and hepatic steatosis, thereby increasing the risk ...of obesity, type 2 diabetes (T2D), non-alcoholic steatohepatitis (NASH), and related comorbidities. Whether this metabolic dysfunction is driven by the excess dietary calories contained in fructose or whether fructose catabolism itself is uniquely pathogenic remains controversial. We sought to test whether a small molecule inhibitor of the primary fructose metabolizing enzyme ketohexokinase (KHK) can ameliorate the metabolic effects of fructose.
The KHK inhibitor PF-06835919 was used to block fructose metabolism in primary hepatocytes and Sprague Dawley rats fed either a high-fructose diet (30% fructose kcal/g) or a diet reflecting the average macronutrient dietary content of an American diet (AD) (7.5% fructose kcal/g). The effects of fructose consumption and KHK inhibition on hepatic steatosis, insulin resistance, and hyperlipidemia were evaluated, along with the activation of DNL and the enzymes that regulate lipid synthesis. A metabolomic analysis was performed to confirm KHK inhibition and understand metabolite changes in response to fructose metabolism in vitro and in vivo. Additionally, the effects of administering a single ascending dose of PF-06835919 on fructose metabolism markers in healthy human study participants were assessed in a randomized placebo-controlled phase 1 study.
Inhibition of KHK in rats prevented hyperinsulinemia and hypertriglyceridemia from fructose feeding. Supraphysiologic levels of dietary fructose were not necessary to cause metabolic dysfunction as rats fed the American diet developed hyperinsulinemia, hypertriglyceridemia, and hepatic steatosis, which were all reversed by KHK inhibition. Reversal of the metabolic effects of fructose coincided with reductions in DNL and inactivation of the lipogenic transcription factor carbohydrate response element-binding protein (ChREBP). We report that administering single oral doses of PF-06835919 was safe and well tolerated in healthy study participants and dose-dependently increased plasma fructose indicative of KHK inhibition.
Fructose consumption in rats promoted features of metabolic dysfunction seen in metabolic diseases such as T2D and NASH, including insulin resistance, hypertriglyceridemia, and hepatic steatosis, which were reversed by KHK inhibition.
•PF-06835919 is a potent inhibitor of fructose metabolism in rats and humans.•Rats fed fructose at levels consistent with the typical American diet develop hyperinsulinemia, hyperlipidemia and steatosis.•KHK inhibition reverses fructose-induced metabolic dysfunction by blocking ChREBP activation.•Due to the global dietary prevalence of fructose, KHK inhibition is a potential pharmacotherapy for metabolic diseases.
Introduction: Glucokinase (GK) is a key regulator of glucose homeostasis, and development of small molecule activators of this enzyme represents a promising new approach for the treatment of type 2 ...diabetes mellitus.Areas covered: This manuscript reviews small molecule patent disclosures between late 2011 and February 2014 for both GK activators (GKAs) and GK−glucokinase regulatory protein (GK−GKRP) disruptors. The review is organized by company and structural class.Expert opinion: The field of GKA research continues to progress, driven by research across many organizations. To date, > 20 candidates have entered clinical development with the most advanced in Phase II trials. Despite promising efficacy, a significant number of early candidates have been discontinued for various reasons including increased risk of hypoglycemia and lack of durability. Recent work in the field has focused on liver-selective activators, which have shown lower hypoglycemia risk, including the development of novel GK-GKRP disruptors that act to indirectly increase hepatic GK activity.
The medicinal chemistry and preclinical biology of imidazopyridine-based inhibitors of diacylglycerol acyltransferase 2 (DGAT2) is described. A screening hit 1 with low lipophilic efficiency (LipE) ...was optimized through two key structural modifications: (1) identification of the pyrrolidine amide group for a significant LipE improvement, and (2) insertion of a sp3-hybridized carbon center in the core of the molecule for simultaneous improvement of N-glucuronidation metabolic liability and off-target pharmacology. The preclinical candidate 9 (PF-06424439) demonstrated excellent ADMET properties and decreased circulating and hepatic lipids when orally administered to dyslipidemic rodent models.
Increased fructose consumption and its subsequent metabolism have been implicated in hepatic steatosis, dyslipidemia, obesity, and insulin resistance in humans. Since ketohexokinase (KHK) is the ...principal enzyme responsible for fructose metabolism, identification of a selective KHK inhibitor may help to further elucidate the effect of KHK inhibition on these metabolic disorders. Until now, studies on KHK inhibition with small molecules have been limited due to the lack of viable in vivo pharmacological tools. Herein we report the discovery of 12, a selective KHK inhibitor with potency and properties suitable for evaluating KHK inhibition in rat models. Key structural features interacting with KHK were discovered through fragment-based screening and subsequent optimization using structure-based drug design, and parallel medicinal chemistry led to the identification of pyridine 12.
Increased fructose consumption and its subsequent metabolism have been implicated in metabolic disorders such as nonalcoholic fatty liver disease and steatohepatitis (NAFLD/NASH) and insulin ...resistance. Ketohexokinase (KHK) converts fructose to fructose-1-phosphate (F1P) in the first step of the metabolic cascade. Herein we report the discovery of a first-in-class KHK inhibitor, PF-06835919 (8), currently in phase 2 clinical trials. The discovery of 8 was built upon our originally reported, fragment-derived lead 1 and the recognition of an alternative, rotated binding mode upon changing the ribose-pocket binding moiety from a pyrrolidinyl to an azetidinyl ring system. This new binding mode enabled efficient exploration of the vector directed at the Arg-108 residue, leading to the identification of highly potent 3-azabicyclo3.1.0hexane acetic acid-based KHK inhibitors by combined use of parallel medicinal chemistry and structure-based drug design.
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