Role Of Aldose Reductase Research Articles

Harnessing the therapeutic potential of Coccinia grandis phytochemicals in diabetes: A computational, DFT calculation and MMGBSA perspective on aldose reductase inhibition

The role of aldose reductase (ALR), the key enzyme of the polyol pathway, has been firmly established in hyperglycemia-induced diabetic complications. Therefore, the present study focused on the screening of phytochemicals reported in Coccinia grandis against ALR using in-silico methodologies encompassing molecular docking, pharmacokinetics, molecular dynamic simulation, free energy calculation (MMGBSA), and quantum mechanics. A comprehensive array of 101 compounds from C. grandis documented in IMPPAT database and different literatures have been selected in this study. These compounds were meticulously docked with the ALR (PDB ID: 1EL3), yielding docking scores spanning a range of −5.8 to −11.0 kcal/mol compared to the positive control epalrestat with a score of −7.9kcal/mol. Among them, four compounds have been emerged as the most promising ALR inhibitors: tiliroside, lukianol B, formononetin, and trachelogenin, with docking scores of −11.0, −10.7, −10.4, and −10.2, respectively. Importantly, these compounds exhibited notable stability throughout 100 ns dynamic simulations compared to the control drug, aligning with Lipinski's rule of 5, standard ADME properties, and evincing an absence of anomalous toxic effects. Therefore, these compounds hold great promise as leads to the development of potent ALR inhibitors; however, further studies are needed to warrant their uses in ameliorating diabetic complications.

The Role of Aldose Reductase in Beta-Amyloid-Induced Microglia Activation.

The occurrence of Alzheimer's disease has been associated with the accumulation of beta-amyloid (β-amyloid) plaques. These plaques activate microglia to secrete inflammatory molecules, which damage neurons in the brain. Thus, understanding the underlying mechanism of microglia activation can provide a therapeutic strategy for alleviating microglia-induced neuroinflammation. The aldose reductase (AR) enzyme catalyzes the reduction of glucose to sorbitol in the polyol pathway. In addition to mediating diabetic complications in hyperglycemic environments, AR also helps regulate inflammation in microglia. However, little is known about the role of AR in β-amyloid-induced inflammation in microglia and subsequent neuronal death. In this study, we confirmed that AR inhibition attenuates increased β-amyloid-induced reactive oxygen species and tumor necrosis factor α secretion by suppressing ERK signaling in BV2 cells. In addition, we are the first to report that AR inhibition reduced the phagocytotic capability and cell migration of BV2 cells in response to β-amyloid. To further investigate the protective role of the AR inhibitor sorbinil in neurons, we co-cultured β-amyloid-induced microglia with stem cell-induced neurons. sorbinil ameliorated neuronal damage in both cells in the co-culture system. In summary, our findings reveal AR regulation of microglia activation as a novel therapeutic target for Alzheimer's disease.

Development and exploration of novel substituted thiosemicarbazones as inhibitors of aldose reductase via in vitro analysis and computational study

The role of aldose reductase (ALR2) in causing diabetic complications is well-studied, with overactivity of ALR2 in the hyperglycemic state leading to an accumulation of intracellular sorbitol, depletion of cytoplasmic NADPH and oxidative stress and causing a variety of different conditions including retinopathy, nephropathy, neuropathy and cardiovascular disorders. While previous efforts have sought to develop inhibitors of this enzyme in order to combat diabetic complications, non-selective inhibition of both ALR2 and the homologous enzyme aldehyde reductase (ALR1) has led to poor toxicity profiles, with no drugs targeting ALR2 currently approved for therapeutic use in the Western world. In the current study, we have synthesized a series of N-substituted thiosemicarbazones with added phenolic moieties, of which compound 3m displayed strong and selective ALR2 inhibitory activity in vitro (IC50 1.18 µM) as well as promising antioxidant activity (75.95% free radical scavenging activity). The target binding modes of 3m were studied via molecular docking studies and stable interactions with ALR2 were inferred through molecular dynamics simulations. We thus report the N-substituted thiosemicarbazones as promising drug candidates for selective inhibition of ALR2 and possible treatment of diabetic complications.

Role of aldose reductase in Ischemic Heart Disease in subjects visiting Punjab Institute of Cardiology, Lahore

Background: Ischemic heart disease (IHD) is one of the major cardiovascular diseases due to insufficient blood supply to cardiac cells. Aldose reductase (AR) is a multifunctional enzyme that converts glucose into sorbitol in the polyol pathway. The main objective of this study is to determine the role of aldose reductase in ischemic heart disease subjects in our local population and its relationship with lipid profile. Methods: This cross-sectional study sampled 100 subjects from Jelani Block of PIC Lahore after ethical approval, categorized into two groups depending on disease condition, i.e., the IHD (n=50) group and Control Group (n=50), including healthy subjects. They were taken together with disease history, age, smoking, hypertension, and physical activity examined as inclusion criteria. The level of biochemical parameters was evaluated by using a chemistry analyzer. Hormonal (AR) and cardiac marker (CK-MB) assessments were performed on the ELISA system using commercially available ELSA diagnostic kits. Results: The results revealed that levels of aldose reeducate and CK-MB was comparatively more significant in the IHD group than control, but total cholesterol (TC), triglycerides (TG), and high-density lipoproteins (HDL) showed no significant difference between the control and IHD group. Conclusion: A statistically non-significant relationship was observed between aldose reductase and CK-MB and lipid profile in the IHD patients, indicating the role of aldose reductase in IHD subjects because it increases oxidative stress in cardiac cells.

186-OR: Safety and Tolerability of the Next Generation Aldose Reductase Inhibitor (ARI) AT-001 Supports Initiation of the Pivotal Trial in Diabetic Cardiomyopathy (DbCM)

The role of Aldose Reductase in diabetes complications, including DbCM is well established. Older generation ARIs were unsuccessful due to lack of selectivity, resulting in off-target toxicity, such as renal and hepatic toxicity, and hypersensitivity reactions. AT-001 is a next generation ARI with improved selectivity and ∼1,000X higher potency. In preclinical studies, AT-001 demonstrated significant reduction of cardiac damage with no off-target inhibition. The safety, tolerability, PK, and PD of AT-001 were assessed in a phase 1/2, three-part, randomized, placebo controlled study (n=120) in adults with type 2 diabetes. AT-001 induced dose-dependent inhibition of sorbitol, the PD biomarker of AR activity. All doses and dosing regimens were well-tolerated. There were no treatment-related serious adverse events (AEs) and no AEs causing discontinuation of study treatment. No clinically relevant changes in liver and kidney function were reported [Table]. The study results support further clinical development to explore potential use of AT-001 as an emerging therapeutic strategy in preventing diabetes complications. A pivotal phase 2/3 study, ARISE-HF (NCT04083339) was initiated to evaluate the safety and efficacy of two doses of AT-001 vs. placebo to improve or prevent the decline of functional capacity in adults with DbCM. Disclosure R. Perfetti: Stock/Shareholder; Self; Applied Therapeutics. F.C. Lawson: Employee; Self; Applied Therapeutics. J. Rosenstock: Research Support; Self; AstraZeneca, Bristol-Myers Squibb, Genentech, Inc., GlaxoSmithKline plc., Lexicon Pharmaceuticals, Inc., Oramed Pharmaceuticals, PegBio Co., Ltd., Pfizer Inc., REMD Biotherapeutics. Other Relationship; Self; Applied Therapeutics, Boehringer Ingelheim Pharmaceuticals, Inc., Eli Lilly and Company, Intarcia Therapeutics, Janssen Pharmaceuticals, Inc., Novo Nordisk Inc., Sanofi. J. Januzzi: Consultant; Self; Roche Diagnostic USA. Research Support; Self; Janssen Pharmaceuticals, Inc. S. Shendelman: Employee; Self; Applied Therapeutics. Stock/Shareholder; Self; Applied Therapeutics. S. Wang: Employee; Self; Applied Therapeutics. A.F. Ghannam: Employee; Self; Applied Therapeutics Inc. Stock/Shareholder; Self; Sanofi US. Funding Applied Therapeutics (NCT04083339)

Exploring antidiabetic potential of adamantyl-thiosemicarbazones via aldose reductase (ALR2) inhibition

The role of aldose reductase (ALR2) in diabetes mellitus is well-established. Our interest in finding ALR2 inhibitors led us to explore the inhibitory potential of new thiosemicarbazones. In this study, we have synthesized adamantyl-thiosemicarbazones and screened them as aldehyde reductase (ALR1) and aldose reductase (ALR2) inhibitors. The compounds bearing phenyl 3a, 2-methylphenyl 3g and 2,6-dimethylphenyl 3m have been identified as most potent ALR2 inhibitors with IC50 values of 3.99 ± 0.38, 3.55 ± 0.26 and 1.37 ± 0.92 µM, respectively, compared with sorbinil (IC50 = 3.14 ± 0.02 μM). The compounds 3a, 3g, and 3m also inhibit ALR1 with IC50 value of 7.75 ± 0.28, 7.26 ± 0.39 and 7.04 ± 2.23 µM, respectively. Molecular docking was also performed for putative binding of potent inhibitors with target enzyme ALR2. The most potent 2,6-dimethylphenyl bearing thiosemicarbazone 3m (IC50 = 1.37 ± 0.92 µM for ALR2) and other two compound 3a and 3g could potentially lead for the development of new therapeutic agents.

Role of aldose reductase in diabetes-induced retinal microglia activation

Diabetes-induced hyperglycemia plays a key pathogenic role in degenerative retinal diseases. In diabetic hyperglycemia, aldose reductase (AR) is elevated and linked to the pathogenesis of diabetic retinopathy (DR) and cataract. Retinal microglia (RMG), the resident immune cells in the retina, are thought to contribute to the proinflammatory phenotype in the diabetic eye. However, we have a limited understanding of the potential role of AR expressed in RMG as a mediator of inflammation in the diabetic retina. Glycated proteins accumulate in diabetes, including Amadori-glycated albumin (AGA) which has been shown to induce a proinflammatory phenotype in various tissues. In this study, we investigated the ability of AGA to stimulate inflammatory changes to RMG and macrophages, and whether AR plays a role in this process. In macrophages, treatment with an AR inhibitor (Sorbinil) or genetic knockdown of AR lowered AGA-induced TNF-α secretion (56% and 40%, respectively) as well as cell migration. In a mouse RMG model, AR inhibition attenuated AGA-induced TNF-α secretion and cell migration (67% and 40%, respectively). To further mimic the diabetic milieu in retina, we cultured RMG under conditions of hypoxia and observed the induction of TNF-α and VEGF protein expression. Downregulation of AR in either a pharmacological or genetic manner prevented hypoxia-induced TNF-α and VEGF expression. In our animal study, increased numbers of RMG observed in streptozotocin (STZ)-induced diabetic retina was substantially lower when diabetes was induced in AR knockout mice. Thus, in vitro and in vivo studies demonstrated that AR is involved in diabetes-induced RMG activation, providing a rationale for targeting AR as a therapeutic strategy for DR.

Benzopyrazines: Synthesis, Characterization and Evaluation as Aldose Reductase Inhibitors

Role of aldose reductase (ALR2) in diabetic complications such as retinopathy, nephropathy, neuropathy, and cataract <i>etc</i>. is well-evident. ALR2 in the first step of polyol pathway reduces glucose to sorbitol whose elevated level leads to diabetic cataract, characterize by clouding of the lens in the eye that affects vision. Inhibition of ALR2 enzyme with small molecules as inhibitor is a rapid approach for diabetic management. In the present study the synthetic route to synthesize desired benzopyrazines and a library of sixteen (16) methyl benzopyrazines were screened against aldose reductase. From the bioactivity results, the 3'-hydroxyphenyl benzopyrazine 6l was found most active (IC₅₀ = 1.34 ± 0.07 <i>µ</i>M) while 3'-bromophenyl analogue 6i showed comparable activity for ALR2 (IC₅₀ = 3.48 ± 0.66 <i>µ</i>M) as compared to standard sorbinil (IC₅₀ = 3.14 ± 0.02 <i>µ</i>M). Both compounds (6l and 6i) showed excellent selectivity for ALR2 over aldehyde reductase (ALR1) which has important role in detoxification of toxic aldehydes. The structure of two regio-isomers were fully characterize by ¹H and ¹³C NMR two dimensional NMR techniques including COSY, NOESY, HSQC, and HMBC. Regio-isomers separation was proved to be difficult in different solvent systems. Only an isomer of 3'-bromo benzopyrazine 6i' was isolated that help to assign the structure of regioisomers from NMR data. All the benzopyrazines were fully characterized by using different spectral techniques including ¹H, ¹³C NMR, IR spectroscopy, and mass spectrometry.

Role of Aldose Reductase in LPS‐inducible Intrahepatic Immune Infiltration and Inflammation

Aldose reductase (AR) is the rate‐limiting enzyme of the polyol pathway that converts glucose to sorbitol, which is further metabolized to fructose. AR has been widely investigated in pathogenesis of diabetic complications, cardiovascular disorders and cancer. Previous studies show that activation of AR is involved in glucose‐induced hepatitis in mice, hepatitis in rats and human autoimmune hepatitis. Recent findings demonstrate that AR is involved in inflammatory hepatic ischemia‐reperfusion injury. The gut‐liver axis is known to be involved in the development of both alcoholic and non‐alcoholic liver diseases. Gut permeability releases endotoxin (lipopolysaccharide, LPS) into circulation and then triggers inflammation. Inflammatory responses are among the most critical pathological processes associated with liver injury. This study investigated the role of AR in intrahepatic immune infiltration/activation and inflammation using mouse models and human specimens from patient with inflammatory liver disease.Wild type (WT, C57BL/6) and aldose reductase knockout mice (ARKO, AKR1B3−/−) were subjected to stimulation with or without LPS (2.0mg/kg) through intraperitoneal injection. Liver histology (H&amp;E staining), intrahepatic immune cell markers (F4/80, chloroacetate esterase stain) and apoptosis (TUNEL) were examined. Intrahepatic immune cells were isolated from mouse livers and analyzed by flow cytometry using immunofluorescence antibodies: anti‐CD11b, anti‐F4/80, anti‐ly6G and anti‐ly6C. The expression levels of AR in hepatitis patient livers were evaluated by real‐time PCR.Proinflammatory cytokines (TNFα, IL‐1β, IL‐6) and chemokines (CXCL2 and MCP‐1/CCL2) were significantly upregulated in WT mice exposed to LPS. The genetic deletion of AR greatly attenuated LPS‐induced cytokines/chemokines. LPS resulted in the infiltration of circulating neutrophils and monocytes into the liver and increased CD11b+Kuffer subsets in WT mice. The lack of AR in ARKO mice was associated with decreased populations of neutrophils, monocytes and CD11b+ Kuffer cells. Specifically, administration of LPS increased neutrophils (F4/80−/CD11b+/Ly6G+/SSCint) by 5 fold in WT mice and AR deficiency reduced this to 3 fold; LPS elevated intrahepatic inflammatory monocytes (F4/80−/CD11b+ /ly6Chi) by 2 fold in WT mice and AR deficiency reduced this to 1 fold. LPS increased the CD11b+Kupffer cell subset (F4/80+CD11b+) by 2 fold in WT mice and AR deficiency decreased this to 1 fold. Hepatic AR expression was significantly upregulated by 2 fold in patients with inflammatory liver disease. Taken together, our data show that AR is a key mediator of hepatic inflammation in response to endotoxin in mice. The upregulation of hepatic AR in patients with hepatitis emphasize the relevance of AR in human liver diseases associated with inflammation. The data also suggest that AR may be a novel therapeutic target for inflammatory hepatic injury.Support or Funding InformationNIH‐NIEHS, NIH‐NIAAA, DOD, VA, and UofL‐IPIBSThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Structure-Activity Relationship Study Reveals Benzazepine Derivatives of Luteolin as New Aldose Reductase Inhibitors for Diabetic Cataract.

Hyperglycaemia in diabetic patients causes diverse range of complications and the earliest among them is diabetic cataract. The role of aldose reductase, the key enzyme in polyol pathway, is well known in the genesis of cataract in chronic diabetic patients. Controlling of sorbitol flux into lens epithelial cells through aldose reductase inhibitors is an important treatment strategy. Due to the side effects of many drugs so far developed, the development of aldose reductase inhibitors from natural sources has gained considerable attention. This study was undertaken to identify suitable drugs for diabetic cataract using molecular modeling and simulation methods. A series of 18 luteolin derivatives having in vitro inhibitory potential against aldose reductase was used to develop a common pharmacophore hypothesis AHRRR and atom-based 3D-QSAR model. The model was used for virtual screening of ZINC database and the resultant hits were docked against aldose reductase. The two drug candidates which belonged to benzazepine class of drugs scored high in the molecular docking. They were further examined for their activity and pharmacokinetic behaviour. Their druglikeness behaviour was found suitable to be used as drugs as per Lipinski's rule of five criteria. Human intestinal absorption (HIA), skin permeability (SP), blood brain barrier (BBB) penetration and plasma protein binding (PPB) was found to be in the acceptable range. Based on the results, these drugs could be considered as potential candidates in further drug development against diabetic cataract.

Identification of Novel Aldose Reductase Inhibitors from Spices: A Molecular Docking and Simulation Study.

Hyperglycemia in diabetic patients results in a diverse range of complications such as diabetic retinopathy, neuropathy, nephropathy and cardiovascular diseases. The role of aldose reductase (AR), the key enzyme in the polyol pathway, in these complications is well established. Due to notable side-effects of several drugs, phytochemicals as an alternative has gained considerable importance for the treatment of several ailments. In order to evaluate the inhibitory effects of dietary spices on AR, a collection of phytochemicals were identified from Zingiber officinale (ginger), Curcuma longa (turmeric) Allium sativum (garlic) and Trigonella foenum graecum (fenugreek). Molecular docking was performed for lead identification and molecular dynamics simulations were performed to study the dynamic behaviour of these protein-ligand interactions. Gingerenones A, B and C, lariciresinol, quercetin and calebin A from these spices exhibited high docking score, binding affinity and sustained protein-ligand interactions. Rescoring of protein ligand interactions at the end of MD simulations produced binding scores that were better than the initially docked conformations. Docking results, ligand interactions and ADMET properties of these molecules were significantly better than commercially available AR inhibitors like epalrestat, sorbinil and ranirestat. Thus, these natural molecules could be potent AR inhibitors.

Role of aldose reductase and arginase inhibitors in diabetic vascular and behavioral complications.

Role of aldose reductase and arginase inhibitors in diabetic vascular and behavioral complications.

Role of Aldose Reductase in the Metabolism and Detoxification of Carnosine-Acrolein Conjugates

Oxidation of unsaturated lipids generates reactive aldehydes that accumulate in tissues during inflammation, ischemia, or aging. These aldehydes form covalent adducts with histidine-containing dipeptides such as carnosine and anserine, which are present in high concentration in skeletal muscle, heart, and brain. The metabolic pathways involved in the detoxification and elimination of these conjugates are, however, poorly defined, and their significance in regulating oxidative stress is unclear. Here we report that conjugates of carnosine with aldehydes such as acrolein are produced during normal metabolism and excreted in the urine of mice and adult human non-smokers as carnosine-propanols. Our studies show that the reduction of carnosine-propanals is catalyzed by the enzyme aldose reductase (AR). Carnosine-propanals were converted to carnosine-propanols in the lysates of heart, skeletal muscle, and brain tissue from wild-type (WT) but not AR-null mice. In comparison with WT mice, the urinary excretion of carnosine-propanols was decreased in AR-null mice. Carnosine-propanals formed covalent adducts with nucleophilic amino acids leading to the generation of carnosinylated proteins. Deletion of AR increased the abundance of proteins bound to carnosine in skeletal muscle, brain, and heart of aged mice and promoted the accumulation of carnosinylated proteins in hearts subjected to global ischemia ex vivo. Perfusion with carnosine promoted post-ischemic functional recovery in WT but not in AR-null mouse hearts. Collectively, these findings reveal a previously unknown metabolic pathway for the removal of carnosine-propanal conjugates and suggest a new role of AR as a critical regulator of protein carnosinylation and carnosine-mediated tissue protection.

Abstract 19716: Role of Aldose Reductase in Perivascular Adipose Tissue and Vascular Dysfunction in Short-Term Diet-Induced Obesity

Obesity is a risk factor for diabetes and cardiovascular (CVD) disease, and the quantity of perivascular adipose tissue (PVAT) associates with CVD risk. To test the hypothesis that changes in PVAT are causal in diet-induced vascular dysfunction, mice (wild type, WT and aldose reductase-null, ARKO, an obesity-sensitive model) were fed a low fat chow diet (10% kcal fat) or high fat chow diet (HFD; 60% kcal fat) for 4 weeks (short-term) in either 8 weeks old or 18 weeks old C57 mice (n=4-6/group). After 4 weeks, body weight and lean and fat mass was measured (DexaScan). Vascular, endothelial and PVAT function and structure were measured in isolated thoracic aorta without and with PVAT in response high potassium solution (100 mM HIK), phenylephrine (PE), acetylcholine (ACh), thromboxane A2 analog (U46619) and sodium nitroprusside (SNP). As expected, HFD increased body weight in all groups although ARKO mice (young and old) gained significantly more body weight, fat grams (whole body, epididymal), and % body fat when compared with age-matched WT mice. Similarly, aortic PVAT mass increased in ARKO mice indicating that PVAT growth mirrored visceral adiposity induced by short-term HFD feeding and enhanced in ARKO mice. PVAT significantly enhanced HIK-induced contractions and SNP-stimulated relaxations (%), decreased U46619-induced tension but neither altered PE-stimulated contraction nor ACh-induced relaxation (%) in isolated aorta of LFD-fed WT. Several of these PVAT effects were altered by age, AR deletion and 4-weeks of HFD feeding. For example, PVAT rescued endothelial dysfunction (ACh, -84.0±7.7%) detected as decreased ACh-induced relaxation in aorta without PVAT (ACh, -43.6±6.8%, p&lt;0.05) of 22-week WT mice fed HFD, indicating that short-term HFD induces compensatory PVAT changes that counteract deleterious endothelium changes -- a novel finding. Effects of PVAT were only slightly modified in ARKO mice despite a greater mass of PVAT, indicating a complicated role of AR deletion in PVAT. These data add to a growing literature that reveals a complex, integrative vascular function of PVAT that is modulated during obesity and metabolic syndrome.

Abstract P202: Role of Lipid Peroxidation--Derived Carbonyls in Left Ventricular Hypertrophy

Pathological left ventricular hypertrophy (LVH) is a key factor in the development of heart failure and cardiomyopathy. It is characterized by increased oxidative stress however the mechanisms by which it affects pathological LVH remain unclear. Because the effects of reactive oxygen species are mediated by products of lipid peroxidation, we hypothesize that myocardial injury induced by LVH is mediated by lipid carbonyls, which form covalent adducts with proteins that induces autophagy. To test this hypothesis, we examined the role of aldose reductase (AKR1B3; AR) an enzyme that catalyzes the detoxification of lipid carbonyls in modulating the cardiac stress responses in WT and AR-null mice hearts that were subjected to transverse aortic constriction (TAC). Two weeks after the TAC cardiac enlargement in the AR-null TAC mice was more prominent compared with WT TAC mice. Hemodynamic analysis of the AR-null TAC mice demonstrated left ventricular dilatation and severe contractile dysfunction compared with WT TAC mice. Expression levels of molecular marker for hypertrophy (ANF) increased 2-3 fold in AR-null TAC compared with the WT-TAC. Western blot analysis of the heart homogenates using anti-4 hydroxy-trans-2-nonenal (HNE) antibody showed that the formation of HNE-protein adduct (300KDa) increased 100-fold and the bands corresponding to molecular weights of 75KDa, 40KDa increased 2 to 3-fold after the TAC in WT hearts and the intensity of these bands in AR-null TAC hearts was significantly higher compared with WT TAC. Immuno-blot analysis of the heart homogenates revealed an increase in the LC3-I to LC3-II conversion in banded hearts compared with sham-operated controls and the autophagic activity was more prominent in the AR-null compared to the WT banded hearts. Isolated adult cardiomyocytes from WT and AR-null hearts perfused with HNE resulted in an increase in autophagy and the increase in autophagic activity was robust in AR-null than in WT myocytes. These data establish that TAC-induced hypertrophy increases protein-HNE-adduct formation and autophagic activity and the deletion of akr1b3 gene exacerbates these responses to pressure overload.

Understanding the Role of Aldose Reductase in Ocular Inflammation

Understanding the Role of Aldose Reductase in Ocular Inflammation

Abstract 4540: Preclinical pharmacology and antitumor activity of CP-744809, a highly selective orally available small molecule inhibitor of aldose reductase

Abstract Aldose reductase (AKR1B1) mediates the first and rate limiting step in the conversion of glucose to polyols that contribute to redox imbalance, formation of reactive oxygen species, and activation of signal transduction pathways that can promote tumor formation and tumor growth. Aldose reductases are overexpressed in a variety of human tumors, and genetic or pharmacological blockade of AKR1B1 has been reported to attenuate these processes. CP-744809 is a highly potent and selective aldose reductase enzyme inhibitor which has been previously shown to provide efficacy in an experimental model of diabetic retinopathy. The compound has properties of high oral bioavailability, very high protein binding, and a very long half life in vivo. In this study, we have characterized the activity of this agent in animal models of angiogenesis and tumor growth. CP-744809 treatment significantly reduced VEGF-induced angiogenesis in a dose-dependent manner in the rat corneal micropocket assay, suggesting a heretofore unrecognized role for aldose reductase in this process. Interestingly, when the related aldose reductase inhibitor Zopolrestat was administered to normal rats, a significantly decreased level of the angiogenic lipid mediator sphingosine-1-phosphate was observed along with other lipid changes. In xenograft models, the CP-744809 treatment was associated with significant and reproducible reduction in tumor size that was dose dependent and superior to treatment with Zopolrestat. Final tumor mass in individual animals was highly correlated with the corresponding intratumoral drug concentration. In contrast, drug concentrations in serum were poorly correlated with drug concentrations in tumor or with tumor mass. Serum drug concentrations at every dose were consistently 7-10 fold higher than those observed in tumor, suggesting a barrier to optimal penetration of tumor tissue by the compound. Pooling data from multiple in vivo studies, the total intra-tumoral drug concentration (protein bound and unbound) required to achieve half maximal efficacy (EC50) was estimated to be 77 micrograms/ml. These results confirm the therapeutic potential of aldose reductase as an interesting cancer target, and have uncovered a novel antiangiogenic activity. They also highlight the obstacle that adequate tumor tissue penetration may pose for clinical development of agents such as CP-744809. Combination treatments with other agents are being evaluated to assess the potential for synergistic activity with the vascular and inflammation modulating properties of aldose reductase inhibitors. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4540.

Aldose Reductase Deficiency Improves Wallerian Degeneration and Nerve Regeneration in Diabeticthy1-YFP Mice

This study examined the role of aldose reductase (AR) in diabetes-associated impaired nerve regeneration using thy1-YFP (YFP) mice. Sciatic nerves of nondiabetic and streptozotocin-induced diabetic AR(+/+)YFP and AR(-/-)YFP mice were transected after 4 weeks of diabetes. Wallerian degeneration and nerve regeneration were evaluated at 1 and 2 weeks postaxotomy by fluorescence microscopy. Motor nerve conduction velocity recovery and regenerating nerve morphometric parameters were determined at 10 and 20 weeks, respectively. There was no difference in the extent of Wallerian degeneration, size of regenerating stump, motor nerve conduction velocity recovery, or caliber of regenerating fibers between nondiabetic AR(+/+)YFP and AR(-/-)YFP mice. In diabetic AR(+/+)YFP mice, Wallerian degeneration was delayed, associated with slower macrophage invasion and abnormal vascularization. Those mice had smaller regenerating stumps, slower motor nerve conduction velocity, and smaller regenerating fibers compared with nondiabetic mice. These features of impaired nerve regeneration were largely attenuated in diabetic AR(-/-)YFP mice. Retarded macrophage invasion and vascularization associated with Wallerian degeneration were normalized in diabetic AR(-/-)YFP mice. These results indicate that AR plays an important role in diabetes-associated impaired nerve regeneration, in part by affecting vascularization and macrophage invasion during Wallerian degeneration. The thy1-YFP mice are valuable tools for further investigation of the mechanism of diabetes-associated nerve regeneration.

Novel Role for Aldose Reductase in Mediating Acute Inflammatory Responses in the Lung

Exaggerated inflammatory responses and the resultant increases in alveolar-capillary permeability underlie the pathogenesis of acute lung injury during sepsis. This study examined the functions of aldose reductase (AR) in mediating acute lung inflammation. Transgenic mice expressing human AR (ARTg) were used to study the functions of AR since mice have low intrinsic AR activity. In a mild cecal ligation and puncture model, ARTg mice demonstrated an enhanced AR activity and a greater inflammatory response as evaluated by circulating cytokine levels, neutrophil accumulation in the lungs, and activation of Rho kinase in lung endothelial cells (ECs). Compared with WT lung cells, ARTg lung cells produced more IL-6 and showed augmented JNK activation in response to LPS stimulation ex vivo. In human neutrophils, AR activity was required for fMLP-included CD11b activation and up-regulation, respiratory burst, and shape changes. In human pulmonary microvascular ECs, AR activity was required for TNF-alpha-induced activation of the Rho kinase/MKK4/JNK pathway and IL-6 production, but not p38 activation or ICAM-1 expression. Importantly, AR activity in both human neutrophils and ECs was required for neutrophil adhesion to TNF-alpha-stimulated ECs. These data demonstrate a novel role for AR in regulating the signaling pathways leading to neutrophil-EC adhesion during acute lung inflammation.

Role of aldose reductase in the high glucose induced expression of fibronectin in human mesangial cells

Aldose reductase (AR) has emerged as a key contributor to the diabetic nephropathy (DN), however, the mechanisms by which AR increases DN remain poorly understood. Here, we report that exposure to high glucose (HG) stimulates fibronectin (FN) from human mesangial cells in culture. Our results show that exposure to HG and overexpression AR increase the expression of FN. This increase was prevented by the AR inhibitors sorbinil and zopolrestat. Treatment with HG and transfected with plasmid PcDNA3.0-AR, resulted in phosphorylation and activation of ERK, JNK and AKT signaling pathway, and increase the expression of FN. Treatment with inhibitor of JNK and AKT signaling pathway decreased the expression of FN. These results show that inhibition of AR may be useful to prevented extracellular matrix (ECM) deposition in diabetic nephropathy, which is regulated by JNK and AKT.