PTP1B Inhibitors Research Articles

Inhibition of protein tyrosine phosphatases enhances cerebral collateral growth in rats.

Arteriogenesis involves the rapid proliferation of preexisting arterioles to fully functional arteries as a compensatory mechanism to overcome circulatory deficits. Stimulation of arteriogenesis has therefore been considered a treatment concept in arterial occlusive disease. Here, we investigated the impact of inhibition of protein tyrosine phosphatases (PTPs) on cerebral arteriogenesis in rats. Arteriogenesis was induced by occlusion of one carotid and both vertebral arteries (three-vessel occlusion (3-VO)). Collateral growth and functional vessel perfusion was assessed 3-35days following 3-VO. Furthermore, animals underwent 3-VO surgery and were treated with the pan-PTP inhibitor BMOV, the SHP-1 inhibitor sodium stibogluconate (SSG), or the PTP1B inhibitor AS279. Cerebral vessel diameters and cerebrovascular reserve capacity (CVRC) were determined, together with immunohistochemistry analyses and proximity ligation assays (PLA) for determination of tissue proliferation and phosphorylation patterns after 7days. The most significant changes in vessel diameter increase were present in the ipsilateral posterior cerebral artery (PCA), with proliferative markers (PCNA) being time-dependently increased. The CVRC was lost in the early phase after 3-VO and partially recovered after 21days. PTP inhibition resulted in a significant increase in the ipsilateral PCA diameter in BMOV-treated animals and rats subjected to PTP1B inhibition. Furthermore, CVRC was significantly elevated in AS279-treated rats compared to control animals, along with hyperphosphorylation of the platelet-derived growth factor-β receptor in the vascular wall in vivo. In summary, our data indicate PTPs as hitherto unrecognized negative regulators in cerebral arteriogenesis. Further, PTP inhibition leading to enhanced collateral growth and blood perfusion suggests PTPs as novel targets in anti-ischemic treatment. PTPs exhibit negative regulatory function in cerebral collateral growth in rats. Inhibition of pan-PTP/PTP1B increases vessel PDGF-β receptor phosphorylation. PTP1B inhibition enhances arteriogenesis and cerebrovascular reserve capacity.

4-Quinolone-3-carboxylic acids as cell-permeable inhibitors of protein tyrosine phosphatase 1B

Protein tyrosine phosphatase 1B is a negative regulator in the insulin and leptin signaling pathways, and has emerged as an attractive target for the treatment of type 2 diabetes and obesity. However, the essential pharmacophore of charged phosphotyrosine or its mimetic confer low selectivity and poor cell permeability. Starting from our previously reported aryl diketoacid-based PTP1B inhibitors, a drug-like scaffold of 4-quinolone-3-carboxylic acid was introduced for the first time as a novel surrogate of phosphotyrosine. An optimal combination of hydrophobic groups installed at C-6, N-1 and C-3 positions of the quinolone motif afforded potent PTP1B inhibitors with low micromolar IC50 values. These 4-quinolone-3-carboxylate based PTP1B inhibitors displayed a 2–10 fold selectivity over a panel of PTP’s. Furthermore, the bidentate inhibitors of 4-quinolone-3-carboxylic acids conjugated with aryl diketoacid or salicylic acid were cell permeable and enhanced insulin signaling in CHO/hIR cells. The kinetic studies and molecular modeling suggest that the 4-quinolone-3-carboxylates act as competitive inhibitors by binding to the PTP1B active site in the WPD loop closed conformation. Taken together, our study shows that the 4-quinolone-3-carboxylic acid derivatives exhibit improved pharmacological properties over previously described PTB1B inhibitors and warrant further preclinical studies.

Targeting the disordered C terminus of PTP1B with an allosteric inhibitor.

PTP1B, a validated therapeutic target for diabetes and obesity, plays a critical positive role in HER2 signaling in breast tumorigenesis. Efforts to develop therapeutic inhibitors of PTP1B have been frustrated by the chemical properties of the active site. We defined a novel mechanism of allosteric inhibition that targets the C-terminal, non-catalytic segment of PTP1B. We present the first ensemble structure of PTP1B containing this intrinsically disordered segment, within which we identified a binding site for the small molecule inhibitor, MSI-1436. We demonstrate binding to a second site close to the catalytic domain, with cooperative effects between the two sites locking PTP1B in an inactive state. MSI-1436 antagonized HER2 signaling, inhibited tumorigenesis in xenografts and abrogated metastasis in the NDL2 mouse model of breast cancer, validating inhibition of PTP1B as a therapeutic strategy in breast cancer. This new approach to inhibition of PTP1B emphasizes the potential of disordered segments of proteins as specific binding sites for therapeutic small molecules.

Back Cover: 3‐Phenylpropanoic Acid‐Based Phosphotyrosine (pTyr) Mimetics: Hit Evolution to a Novel Orally Active Protein Tyrosine Phosphatase 1B (PTP1B) Inhibitor (ChemMedChem 5/2014)

The back cover picture shows the discovery of a novel orally active PTP1B inhibitor as a potential antidiabetic agent. This potent PTP1B inhibitor was evolved from a previously identified 3-phenylpropanoic acid-based hit structure. It showed significant in vivo activity and a suitable pharmacokinetic profile. The results provide a new chemotype of PTP1B inhibitors. For further details, see the Communication by Zhiyan Xiao et al. on p. 918 ff.

Design and Synthesis of Novel 2- Substituted Benzothiazole Compounds as PTP1B Inhibitors

Design and Synthesis of Novel 2- Substituted Benzothiazole Compounds as PTP1B Inhibitors

Structural characterization and bioactivity evaluation of an acidic proteoglycan extract from Ganoderma lucidum fruiting bodies for PTP1B inhibition and anti‐diabetes

A water-soluble PTP1B inhibitor, named FYGL-a, was fractionated for structure investigation and bioactivity evaluation. FYGL-a is an ingredient of a reported antihyperglycemia extract from Ganoderma Lucidum fruiting bodies. Composition analysis indicated that FYGL-a was a 100.2 kDa acidic proteoglycan, consisting of 85 ± 2% heteropolysaccharide chain with rhamnose, galactose, glucose, and glucuronic acid residues in a mole ratio of 1.0:3.7:3.9:2.0, and the 15 ± 2% protein moiety of FYGL-a was covalently bonded to the polysaccharide chain in O-linkage type via threonine residues. The complete sequence of FYGL-a was characterized systematically by periodate oxidation, Smith degradation, methylation analysis, (1)H & (13)C 1D NMR, and 2D NMR (HSQC, HMBC, NOESY, COSY, & TOCSY). The chemical structure of FYGL-a was determined as following, which may play special role in the competitive inhibition of PTP1B and antihyperglycemia potency.

Design and synthesis of paracaseolide A analogues as selective protein tyrosine phosphatase 1B inhibitors.

A series of structurally related analogues of the natural product paracaseolide A were synthesized and identified as potent PTP1B inhibitors. Among these analogues, compound 10 in particular showed improved PTP1B enzyme inhibitory activity, high selectivity for PTP1B over TC-PTP, and improved cellular effects.

Synthesis of Bioactive Aryl Imidazole Derivatives and Their Applications for the pH-Induced Luminescence Sensing Probe†

Six kinds of imidazo[4,5-f][1,10]phenanthroline derivatives(3a—3f) were designed and synthesized based on [1,10]phenanthroline skeleton. The inhibition of the target compounds on PTP1B was studied and the highest inhibition rate could be up to(84. 56 ± 1. 78) %. The results indicated that the target compounds could be used as the potential PTP1B inhibitors and provide important therapy reference for the modern Ⅱ diabetes and obesity. Owing to the excellent optical performance of 1,10-phenanthroline,the effects of pH on the luminescence properties of the target products(3a—3f) were also studied and the phenomenon of the protonation and deprotonation in the B-R buffer solution were explored. Taking quinine bisulphate as a reference,the highest luminescence quantum yield of compounds 3 was 0. 53. With the increase in pH value,the luminescence intensity of compounds 3 increased. In the range of pH = 6—8,compounds 3 gave a strong and steady luminescence. However,the luminescence intensity of compounds 3 reduced when pH value was higher than 8. As a result,compounds 3 could be used as pH luminescence sensing probe.

ChemInform Abstract: Synthesis of Novel Coumarin Derivatives and in vitro Biological Evaluation as Potential PTP 1B Inhibitors.

AbstractThe new synthesized compounds are tested for their inhibition activity against the protein tyrosine phosphatase 1B (PTB 1B).

In silico accounting of novel pyridazine analogues as h-PTP 1B inhibitors: pharmacophore modelling, atom-based 3D QSAR and docking studies

PTP 1B, a negative regulator of insulin signalling pathway, has been rigorously investigated for its potential for design and development of drugs for the management of type 2 diabetes. Pharmacophore modelling, atom-based 3D QSAR and docking studies were performed on a series of 37 pyridazine derivatives reported as PTP 1B inhibitors. A five-point pharmacophore model consisting of two hydrogen bond acceptors (A), one hydrogen bond donor (D), one hydrophobic (H) and one aromatic ring (R) with discrete geometries as pharmacophoric features were developed for a predictive 3D QSAR model. The robustness of the generated model was validated by good correlation coefficient value (r2 = 0.832), Pearson-R value (0.8593), cross-validated correlation coefficient (q2 = 0.663). This study investigated some of the indispensible structural features of pyridazine analogues which can further be exploited to optimize h-PTP 1B inhibitors.

Discovery of novel PTP1B inhibitors via pharmacophore-oriented scaffold hopping from Ertiprotafib

An integrated molecular design strategy combining pharmacophore recognition and scaffold hopping was exploited to discover novel PTP1B inhibitors based on the known PTP1B inhibitor Ertiprotafib. A composite pharmacophore model was proposed from the interaction mode of Ertiprotafib, and 21 diverse molecules from five distinct structural classes were designed and synthesized accordingly. New compounds with considerable inhibition against PTP1B were identified from each series, and the most active compound 3a showed IC50 value of 1.3μmolL−1 against human recombinant PTP1B. Docking study indicated that the new inhibitors assumed binding modes similar to that of Ertiprotafib.

A Conserved Rod Domain Phosphotyrosine That Is Targeted by the Phosphatase PTP1B Promotes Keratin 8 Protein Insolubility and Filament Organization*♦

Post-translational modifications are important functional determinants for intermediate filament (IF) proteins. Phosphorylation of IF proteins regulates filament organization, solubility, and cell-protective functions. Most known IF protein phosphorylation sites are serines localized in the variable "head" and "tail" domain regions. By contrast, little is known about site-specific tyrosine phosphorylation or its implications on IF protein function. We used available proteomic data from large scale studies to narrow down potential phospho-tyrosine sites on the simple epithelial IF protein keratin 8 (K8). Validation of the predicted sites using a pan-phosphotyrosine and a site-specific antibody, which we generated, revealed that the highly conserved Tyr-267 in the K8 "rod" domain was basally phosphorylated. The charge at this site was critically important, as demonstrated by altered filament organization of site-directed mutants, Y267F and Y267D, the latter exhibiting significantly diminished solubility. Pharmacological inhibition of the protein-tyrosine phosphatase PTP1B increased K8 Tyr-267 phosphorylation, decreased solubility, and increased K8 filament bundling, whereas PTP1B overexpression had the opposite effects. Furthermore, there was significant co-localization between K8 and a "substrate-trapping" mutant of PTP1B (D181A). Because K8 Tyr-267 is conserved in many IFs (QYE motif), we tested the effect of the paralogous Tyr in glial fibrillary acidic protein (GFAP), which is mutated in Alexander disease (Y242D). Similar to K8, Y242D GFAP exhibited highly irregular filament organization and diminished solubility. Our results implicate the rod domain QYE motif tyrosine as an important determinant of IF assembly and solubility properties that can be dynamically modulated by phosphorylation.

PTP1B Inhibitory Secondary Metabolites from Marine-Derived Fungal Strains Penicillium spp. and Eurotium sp.

The selective inhibition of PTP1B has been widely recognized as a potential drug target for the treatment of type 2 diabetes and obesity. In the course of screening for PTP1B inhibitory fungal metabolites, the organic extracts of several fungal species isolated from marine environments were found to exhibit significant inhibitory effects, and the bioassay-guided investigation of these extracts resulted in the isolation of fructigenine A (1), cyclopenol (2), echinulin (3), flavoglaucin (4), and viridicatol (5). The structures of these compounds were determined mainly by analysis of NMR and MS data. These compounds inhibited PTP1B activity with 50% inhibitory concentration values of 10.7, 30.0, 29.4, 13.4, and 64.0 micrometer, respectively. Furthermore, the kinetic analysis of PTP1B inhibition by compounds 1 and 5 suggested that compound 1 inhibited PTP1B activity in a noncompetitive manner, whereas compound 5 inhibited PTP1B activity in a competitive manner.

Adiponectin inhibits leptin-induced oncogenic signalling in oesophageal cancer cells by activation of PTP1B

Obesity is characterised by hyperleptinaemia and hypoadiponectinaemia and these metabolic abnormalities may contribute to the progression of several obesity-associated cancers including oesophageal adenocarcinoma (OAC). We have examined the effects of leptin and adiponectin on OE33 OAC cells. Leptin stimulated proliferation, invasion and migration and inhibited apoptosis in a STAT3-dependant manner. Leptin-stimulated MMP-2 secretion in a partly STAT3-dependent manner and MMP-9 secretion via a STAT3-independent pathway. Adiponectin inhibited leptin-induced proliferation, migration, invasion, MMP secretion and reduced the anti-apoptotic effects: these effects of adiponectin were ameliorated by both a non-specific tyrosine phosphatase inhibitor and a specific PTP1B inhibitor. Adiponectin reduced leptin-stimulated JAK2 activation and STAT3 transcriptional activity in a PTP1B-sensitive manner and adiponectin increased both PTP1B protein and activity. We conclude that adiponectin restrains leptin-induced signalling and pro-carcinogenic behaviour by inhibiting the early events in leptin-induced signal transduction by activating PTP1B. Relative adiponectin deficiency in obesity may contribute to the promotion of OAC.

A paradigm for development of novel PTP 1B inhibitors: Pharmacophore modelling, atom-based 3D-QSAR and docking studies

Inhibitors of protein tyrosine phosphatase 1B (PTP 1B) are of great interest for the development of newer therapeutics for the management of type 2 diabetes mellitus (T2DM). In order to understand structural requirement of molecules to act as PTP 1B inhibitors, ligand-based pharmacophore model, atom-based 3D-QSAR and structure-based drug design studies have been performed on a series of thiophene derivatives to correlate their molecular architecture with PTP 1B inhibitory activity. A five-point pharmacophore hypothesis with one hydrogen acceptor (A), two negative ionic (N), and two aromatic rings (R) as pharmacophoric features were developed using PHASE module of Schrodinger suite. The pharmacophore hypothesis was characterized by good PLS statistics (survival score = 3.894, the best cross validated r2 (Q2) = 0.737, regression coefficient r2 = 0.968, Pearson-R = 0.887 and F value = 253.3). Docking studies demonstrated binding orientations of ligands in dataset with bidentate binding pockets of the enzyme and importance of hydrophobic groups. Taken together, Partial least square (PLS) generated 3D-QSAR pharmacophore and regression cubes along with structure based drug design provided a three dimensional topological view of active site that can be used for rational modification of ligands for optimal PTP 1B inhibitory activity.

Calix[4]arene methylenebisphosphonic acids as inhibitors of protein tyrosine phosphatase 1B

Сalix[4]arenes bearing methylenebisphosphonic or hydroxymethylenebisphosphonic acid fragments at the wide rim of the macrocycle were studied as inhibitors of PTP1B. Some of the inhibitors showed IC50 values in the micromolar range and good selectivity in comparison with other protein tyrosine phosphatases such as TC-PTP, PTPβ, LAR, and CD45. Kinetic studies indicated that the calix[4]arene derivatives influence PTP1B activity as slow-binding inhibitors. Based on molecular docking results, the binding modes of the macrocyclic bisphosphonates in the active centre of PTP1B are discussed.

Gene deletion of protein tyrosine phosphatase 1B limits cardiovascular dysfunction and mortality during endotoxinic shock

Sepsis-associated cardiovascular dysfunction is one of the main causes of mortality in critically ill patients. PTP1B is negative regulator of insulin signaling and endothelial Nitric Oxide (NO) production, two mechanisms likely involved in the pathogenesis of sepsis. We recently showed that gene deletion or pharmacological inhibition of PTP1B improves endothelial dysfunction and reduces the severity of heart failure. The aim of the present study was to assess the effect of PTP1B gene deletion on lipopolysaccharide (LPS)-induced cardiovascular dysfunction and mortality in mice. PTP1B-/- or wild-type (WT) mice received LPS (15mg/kg) or vehicle followed by subcutaneous saline resuscitation (30ml/kg). LPS significantly enhanced cardiac and arterial PTP1B mRNA expression. Compared with WT, PTP1B-/- mice displayed markedly reduced mortality (Survival 4 days after LPS: WT: 0%; PTP1B-/- 70%, p<0.01), associated with a higher locomotor activity. Evaluation of vascular function 8h after LPS in isolated mesenteric resistance arteries (arteriograph system) showed that PTP1B-/- LPS mice had improved contractile response to phenylephrine, and restored flow mediated, NO dependent-dilatation (% dilatation to 200μl/min: WT 6,3±3; PTP1B-/- 16,5±2, p<0.05) associated with significant increases in phosphorylation of Akt and eNOS, and reduced mRNA expression of VCAM-1, ICAM-1, COX-2, IL-1β, iNOS and Gp91phox (PCR). Evaluation of left ventricular (LV) function by echocardiography, and pressure-volume curves 8h after LPS revealed reduced cardiac dysfunction in PTP1B-/- mice as shown by an increased LV fractional shortening (WT 17,3±1; PTP1B-/- 24±1, p<0.05) and LV end systolic pressure-volume relation (WT 16±2; PTP1B-/- 20±2, p<0.05) together with reduced LV end diastolic pressure-volume relation (WT 4,7±1,7; PTP1B-/- 2.4±0.9 mmHg/RVU, p<0.05). Improved cardiac contractility was also observed ex-vivo in hearts isolated and perfused 8h after LPS (LV Developed Pressure: WT 25±5; PTP1B-/- 50±5 mmHg, p<0.05). Improved cardiac function was associated with significant decreases in myocardial markers of inflammation and oxidative stress (VCAM-1, ICAM-1, CD45, IL-1β, TNF-α and Gp91phox), reduced P38 and ERK1/2 phosphorylation and limited decrease of phospholamban phosphorylation (WT -42%; PTP1B-/- -22.8, p<0.05). Thus, we demonstrate for the first time that PTP1B gene deletion protects against lipopolysaccharide-induced cardiovascular dysfunction and mortality. These results suggest that PTP1B is an attractive target for the treatment of sepsis.

PP102—Molecular docking research & in-vitro analysis of novel natural and synthetic PTP 1B inhibitors as potential therapeutic target for diabetes mellitus

PP102—Molecular docking research & in-vitro analysis of novel natural and synthetic PTP 1B inhibitors as potential therapeutic target for diabetes mellitus

The first synthesis of natural disulfide bruguiesulfurol and biological evaluation of its derivatives as a novel scaffold for PTP1B inhibitors

Bruguiesulfurol (1), a cyclic 4-hydroxy-dithiosulfonate isolated from mangrove plant Bruguiera gymnorrhiza, was concisely synthesized for the first time in four steps, and a series of its synthetic derivatives were evaluated for in vitro inhibitory effects on PTP1B and related PTPs. Some derivatives were found to have improved pharmacological profile compared with hit 1. Among them, 5a showed the potent selectivity towards PTP1B over other PTPs, including TCPTP, and 7j exhibited the strongest PTP1B inhibitory activity with an IC50 value of 4.54μM.

3D-QSAR Studies on a Series of 2,4-Thiazolidinedione Derivatives: A Self- Organizing Molecular Field Analysis Approach to Design Novel PTP 1B Inhibitors

Diabetes mellitus is a group of metabolic disorders characterised by chronic hyperglycemia resulting either from a deficiency of insulin, or decreased ability to transduce the insulin signal, or both. Insulin resistance and β-cell dysfunction are two fundamental defects known to precede the onset of type 2 diabetes. PTP 1B is considered to function as a negative regulator of insulin signal transduction by dephosphorylating phosphotyrosine residues. 2,4-Thiazolidinediones (TZDs) have long been considered as antihyperglycemic agents which act by ameliorating insulin resistance and thereby normalizing elevated blood glucose level. A three dimensional quantitative structure-activity relationship (3D-QSAR) study was performed on a novel class of thiazolidinedione derivatives using self-organizing molecular field analysis (SOMFA) to correlate their molecular architecture with observed PTP 1B inhibitory activities. The master grid maps derived from the best model were used to display the contribution of both electrostatic and shape potential that can be mapped back onto structural features relating to the trends in inhibitory activities. The present SOMFA study indicated the indispensable molecular features which can be further explored for structural modifications of these lead molecules in order to optimize PTP 1B inhibitory activity.