The Concise Guide to PHARMACOLOGY 2015/16: Overview

Mitochondrial dysfunction in inflammatory responses and cellular senescence: pathogenesis and pharmacological targets for chronic lung diseases

Mitochondria are dynamic organelles, which couple the various cellular processes that regulate metabolism, cell proliferation and survival. Environmental stress can cause mitochondrial dysfunction and dynamic changes including reduced mitochondrial biogenesis, oxidative phosphorylation and ATP production, as well as mitophagy impairment, which leads to increased ROS, inflammatory responses and cellular senescence. Oxidative stress, inflammation and cellular senescence all have important roles in the pathogenesis of chronic lung diseases, such as chronic obstructive pulmonary disease, pulmonary fibrosis and bronchopulmonary dysplasia. In this review, we discuss the current state on how mitochondrial dysfunction affects inflammatory responses and cellular senescence, the mechanisms of mitochondrial dysfunction underlying the pathogenesis of chronic lung diseases and the potential of mitochondrial transfer and replacement as treatments for these diseases.

Effects of glucagon-like peptide-1 on the differentiation and metabolism of human adipocytes

BACKGROUND AND PURPOSE

Glucagon-like peptide-1 (GLP-1) analogues improve glycaemic control in type 2 diabetic (T2D) patients and cause weight loss in obese subjects by as yet unknown mechanisms. We recently demonstrated that the GLP-1 receptor, which is present in adipocytes and the stromal vascular fraction of human adipose tissue (AT), is up-regulated in AT of insulin-resistant morbidly obese subjects compared with healthy lean subjects. The aim of this study was to explore the effects of in vitro and in vivo administration of GLP-1 and its analogues on AT and adipocyte functions from T2D morbidly obese subjects.

EXPERIMENTAL APPROACH

We analysed the effects of GLP-1 on human AT and isolated adipocytes in vitro and the effects of GLP-1 mimetics on AT of morbidly obese T2D subjects in vivo.

KEY RESULTS

GLP-1 down-regulated the expression of lipogenic genes when administered during in vitro differentiation of human adipocytes from morbidly obese patients. GLP-1 also decreased the expression of adipogenic/lipogenic genes in AT explants and mature adipocytes, while increasing that of lipolytic markers and adiponectin. In 3T3-L1 adipocytes, GLP-1 decreased free cytosolic Ca2+ concentration ([Ca2+]i). GLP-1-induced responses were only partially blocked by GLP-1 receptor antagonist exendin (9–39). Moreover, administration of exenatide or liraglutide reduced adipogenic and inflammatory marker mRNA in AT of T2D obese subjects.

CONCLUSIONS AND IMPLICATIONS

Our data suggest that the beneficial effects of GLP-1 are associated with changes in the adipogenic potential and ability of AT to expand, via activation of the canonical GLP-1 receptor and an additional, as yet unknown, receptor.

Apelin-13 administration protects against ischaemia/reperfusion-mediated apoptosis through the FoxO1 pathway in high-fat diet-induced obesity

BACKGROUND AND PURPOSE

Apelin-13, an endogenous ligand for the apelin (APJ) receptor, behaves as a potent modulator of metabolic and cardiovascular disorders. Here, we examined the effects of apelin-13 on myocardial injury in a mouse model combining ischaemia/reperfusion (I/R) and obesity and explored their underlying mechanisms.

EXPERIMENTAL APPROACH

Adult male C57BL/6J mice were fed a normal diet (ND) or high-fat diet (HFD) for 6 months and then subjected to cardiac I/R. The effects of apelin-13 post-treatment on myocardial injury were evaluated in HFD-fed mice after 24 h I/R. Changes in protein abundance, phosphorylation, subcellular localization and mRNA expression were determined in cardiomyoblast cell line H9C2, primary cardiomyocytes and cardiac tissue from ND- and HFD-fed mice. Apoptosis was evaluated by TUNEL staining and caspase-3 activity. Mitochondrial ultrastructure was analysed by electron microscopy.

KEY RESULTS

In HFD-fed mice subjected to cardiac I/R, i.v. administration of apelin-13 significantly reduced infarct size, myocardial apoptosis and mitochondrial damage compared with vehicle-treated animals. In H9C2 cells and primary cardiomyocytes, apelin-13 induced FoxO1 phosphorylation and nuclear exclusion. FoxO1 silencing by siRNA abolished the protective effects of apelin-13 against hypoxia-induced apoptosis and mitochondrial ROS generation. Finally, apelin deficiency in mice fed a HFD resulted in reduced myocardial FoxO1 expression and impaired FoxO1 distribution.

CONCLUSIONS AND IMPLICATIONS

These data reveal apelin as a novel regulator of FoxO1 in cardiac cells and provide evidence for the potential of apelin-13 in prevention of apoptosis and mitochondrial damage in conditions combining I/R injury and obesity.

Inhibition of fatty acid synthase is protective in pulmonary hypertension

BACKGROUND AND PURPOSE

In pulmonary hypertension (PH), similar to cancer, there is altered energy metabolism, apoptosis resistance and cellular proliferation leading to pulmonary vascular remodelling. Proliferating cells exhibit higher rate of de novo fatty acid synthesis to provide lipids for membrane formation and energy production. As inhibition of de novo fatty acid synthesis proved protective in cancer experimentally, therefore, it was hypothesized that modulation of de novo fatty acid synthesis by inhibition of fatty acid synthase (FAS) may prove beneficial for PH.

EXPERIMENTAL APPROACH

For in vitro studies, human pulmonary artery smooth muscle cells (HPASMCs) were exposed to hypoxia and to induce PH in vivo, rats were treated with monocrotaline (MCT). FAS was inhibited by siRNA (60 nM) and C75 (2 mg·kg(-1) , i.p. once a week for 5 weeks) in in vitro and in vivo studies respectively.

RESULTS

Increased expression and activity of FAS were observed in hypoxic HPASMCs and lungs of MCT-treated rats. Inhibition of FAS increased apoptosis and glucose oxidation, but decreased proliferation and markers of autophagy, glycolysis and insulin resistance in hypoxic HPASMCs. It also improved the mitochondrial functions as evident by increased level of ATP and restoration of normal level of ROS and membrane potential of mitochondria. In MCT-treated rats, FAS inhibition decreased right ventricular pressure, hypertrophy, pulmonary vascular remodelling (increased apoptosis and decreased proliferation of cells) and endothelial dysfunction in lungs.

CONCLUSIONS

Our results demonstrate that FAS activity is modulated in PH, and its inhibition may provide a new therapeutic approach to treat PH.

An update on PPAR activation by cannabinoids

Some cannabinoids activate the different isoforms of PPARs (α, β and γ), as shown through the use of reporter gene assays, binding studies, selective antagonists and knockout studies. Activation of all isoforms, but primarily PPARα and γ, mediates some (but not all) of the analgesic, neuroprotective, neuronal function modulation, anti-inflammatory, metabolic, anti-tumour, gastrointestinal and cardiovascular effects of some cannabinoids, often in conjunction with activation of the more traditional target sites of action such as the cannabinoid CB1 and CB2 receptors and the TRPV1 ion channel. PPARs also mediate some of the effects of inhibitors of endocannabinoid degradation or transport. Cannabinoids may be chaperoned to the PPARs by fatty acid binding proteins. The aims of this review are to update the evidence supporting PPAR activation by cannabinoids and to review the physiological responses to cannabinoids that are mediated, and not mediated, by PPAR activation.

Immunotherapy of cancer: from monoclonal to oligoclonal cocktails of anti-cancer antibodies: IUPHAR Review 18

Antibody-based therapy of cancer employs monoclonal antibodies (mAbs) specific to soluble ligands, membrane antigens of T-lymphocytes or proteins located at the surface of cancer cells. The latter mAbs are often combined with cytotoxic regimens, because they block survival of residual fractions of tumours that evade therapy-induced cell death. Antibodies, along with kinase inhibitors, have become in the last decade the mainstay of oncological pharmacology. However, partial and transient responses, as well as emergence of tumour resistance, currently limit clinical application of mAbs. To overcome these hurdles, oligoclonal antibody mixtures are being tested in animal models and in clinical trials. The first homo-combination of two mAbs, each engaging a distinct site of HER2, an oncogenic receptor tyrosine kinase (RTK), has been approved for treatment of breast cancer. Likewise, a hetero-combination of antibodies to two distinct T-cell antigens, PD1 and CTLA4, has been approved for treatment of melanoma. In a similar vein, additive or synergistic anti-tumour effects observed in animal models have prompted clinical testing of hetero-combinations of antibodies simultaneously engaging distinct RTKs. We discuss the promise of antibody cocktails reminiscent of currently used mixtures of chemotherapeutics and highlight mechanisms potentially underlying their enhanced clinical efficacy.

Intranasal exposure to monoclonal antibody Fab fragments to Japanese cedar pollen Cry j1 suppresses Japanese cedar pollen-induced allergic rhinitis

BACKGROUND AND PURPOSE

Fab fragments (Fabs) of antibodies have the ability to bind to specific allergens but lack the Fc portion that exerts effector functions via binding to receptors including FcεR1 on mast cells. In the present study, we investigated whether intranasal administration of the effector function-lacking Fabs of a monoclonal antibody IgG1 (mAb, P1-8) to the major allergen Cry j1 of Japanese cedar pollen (JCP) suppressed JCP-induced allergic rhinitis in mice.

EXPERIMENTAL APPROACH

Balb/c mice sensitized with JCP on days 0 and 14 were challenged intranasally with the pollen on days 28, 29, 30 and 35. Fabs prepared by the digestion of P1-8 with papain were also administered intranasally 15 min before each JCP challenge.

KEY RESULTS

Intranasal administration of P1-8 Fabs was followed by marked suppression of sneezing and nasal rubbing in mice with JCP-induced allergic rhinitis. The suppression of these allergic symptoms by P1-8 Fabs was associated with decreases in mast cells and eosinophils and decreased hyperplasia of goblet cells in the nasal mucosa.

CONCLUSIONS AND IMPLICATIONS

These results demonstrated that intranasal exposure to P1-8 Fabs was effective in suppressing JCP-induced allergic rhinitis in mice, suggesting that allergen-specific mAb Fabs might be used as a tool to regulate allergic pollinosis.

Madecassoside ameliorates bleomycin-induced pulmonary fibrosis in mice through promoting the generation of hepatocyte growth factor via PPAR-γ in colon

BACKGROUND AND PURPOSE

Madecassoside has potent anti-pulmonary fibrosis (PF) effects when administered p.o., despite having extremely low oral bioavailability. Herein, we explored the mechanism of this anti-PF effect with regard to gut hormones.

EXPERIMENTAL APPROACH

A PF model was established in mice by intratracheal instillation of bleomycin. Haematoxylin and eosin stain and Masson's trichrome stain were used to assess histological changes in the lung. Quantitative-PCR and Western blot detected mRNA and protein levels, respectively, and cytokines were measured by ELISA. Small interfering RNA was used for gene-silencing. EMSA was applied to detect DNA-binding activity.

KEY RESULTS

Administration of madecassoside, p.o., but not its main metabolite madecassic acid, exhibited a direct anti-PF effect in mice. However, i.p. madecassoside had no anti-PF effect. Madecassoside increased the expression of hepatocyte growth factor (HGF) in colon tissues, and HGF receptor antagonists attenuated its anti-PF effect. Madecassoside facilitated the secretion of HGF from colonic epithelial cells by activating the PPAR-γ pathway, as shown by an up-regulation of PPAR-γ mRNA expression, nuclear translocation and DNA-binding activity both in vitro and in vivo. Also GW9662, a selective PPAR-γ antagonist, almost completely prevented the madecassoside-induced increased expression of HGF and amelioration of PF.

CONCLUSIONS AND IMPLICATIONS

The potent anti-PF effects induced by p.o. madecassoside in mice are not mediated by its metabolites or itself after absorption into blood. Instead, madecassoside increases the activity of PPAR-γ, which subsequently increases HGF expression in colonic epithelial cells. HGF then enters into the circulation and lung tissue to exert an anti-PF effect.

Anti-oxidative effect of AST-120 on kidney injury after myocardial infarction

BACKGROUND AND PURPOSE

Chronic kidney disease (CKD) is a crucial risk factor for cardiovascular disease (CVD), and combined CKD and CVD further increases morbidity and mortality. Here, we investigated effects of AST-120 on oxidative stress and kidney injury using a model of myocardial infarction (MI) in rats.

EXPERIMENTAL APPROACH

At 10 weeks, male spontaneously hypertensive rats (SHR) were divided into three groups: SHR (n = 6), MI (n = 8) and MI + AST-120 (n = 8). AST-120 administration was started at 11 weeks after MI. At 18 weeks, the rats were killed, and blood and urine, mRNA expression and renal histological analyses were performed. Echocardiography was performed before and after MI.

KEY RESULTS

At 18 weeks, the BP was significantly lower in the MI and MI+AST-120 groups than in the SHR group. Elevated levels of indoxyl sulfate (IS), one of the uremic toxins, in serum and urine were reduced by AST-120 treatment, compared with the MI group. Markers of oxidative stress in urine and serum biomarkers of kidney injury were decreased in the MI+AST-120 group compared with the other two groups. Renal expression of mRNAs for kidney injury related-markers were decreased in the MI+AST-120 group, compared with the MI group. In vitro data also supported the influence of IS on kidney injury. Immunohistological analysis showed that intrarenal oxidative stress was reduced by AST-120 administration.

CONCLUSIONS AND IMPLICATIONS

Serum IS was increased after MI and treatment with AST-120 may have protective effects on kidney injury after MI by suppressing oxidative stress.

Possible pharmacotherapy for nifedipine-induced gingival overgrowth: 18α-glycyrrhetinic acid inhibits human gingival fibroblast growth

BACKGROUND AND PURPOSE

This investigation aimed to establish the basis of a pharmacotherapy for nifedipine-induced gingival overgrowth. Gingival overgrowth has been attributed to the enhanced growth of gingival fibroblasts. In this study, we investigated the effects of 18-α-glycyrrhetinic acid (18α-GA) on growth, the cell cycle, and apoptosis and on the regulators of these processes in gingival fibroblasts isolated from patients who presented with nifedipine-induced gingival overgrowth.

EXPERIMENTAL APPROACH

Gingival fibroblasts were cultured in medium containing 1% FBS with/without 10 μM 18α-GA for 24 or 48 h, and the cell number, cell cycle phase distribution, relative DNA content, apoptotic cell number and morphological characteristics of the cells undergoing apoptosis were measured together with the levels of proteins that regulate these processes and the level of caspase activity.

KEY RESULTS

18α-GA significantly decreased cell numbers and significantly increased the percentage of cells in the sub-G1 and G0 /G1 phases of the cell cycle and the number of apoptotic cells. Nuclear condensation and fragmentation of cells into small apoptotic bodies appeared in the fibroblasts treated with 18α-GA. In addition, 18α-GA significantly decreased the protein levels of cyclins A and D1, CDKs 2 and 6, phosphorylated Rb (ser(780) and ser(807/811)), Bcl-xL and Bcl-2 and increased the protein levels of p27, cytosolic cytochrome c, pro-caspase-3, and cleaved caspase-3 and the activities of caspases 3 and 9.

CONCLUSIONS AND IMPLICATIONS

18α-GA inhibited gingival fibroblast growth by suppressing the G1 /S phase transition and inducing apoptosis. In conclusion, 18α-GA may be used as a pharmacotherapy for nifedipine-induced gingival overgrowth.

Biased ligand quantification in drug discovery: from theory to high throughput screening to identify new biased μ opioid receptor agonists

BACKGROUND AND PURPOSE

Biased GPCR ligands are able to engage with their target receptor in a manner that preferentially activates distinct downstream signalling and offers potential for next generation therapeutics. However, accurate quantification of ligand bias in vitro is complex, and current best practice is not amenable for testing large numbers of compound. We have therefore sought to apply ligand bias theory to an industrial scale screening campaign for the identification of new biased μ receptor agonists.

EXPERIMENTAL APPROACH

μ receptor assays with appropriate dynamic range were developed for both Gαi -dependent signalling and β-arrestin2 recruitment. Δlog(Emax /EC50 ) analysis was validated as an alternative for the operational model of agonism in calculating pathway bias towards Gαi -dependent signalling. The analysis was applied to a high throughput screen to characterize the prevalence and nature of pathway bias among a diverse set of compounds with μ receptor agonist activity.

KEY RESULTS

A high throughput screening campaign yielded 440 hits with greater than 10-fold bias relative to DAMGO. To validate these results, we quantified pathway bias of a subset of hits using the operational model of agonism. The high degree of correlation across these biased hits confirmed that Δlog(Emax /EC50 ) was a suitable method for identifying genuine biased ligands within a large collection of diverse compounds.

CONCLUSIONS AND IMPLICATIONS

This work demonstrates that using Δlog(Emax /EC50 ), drug discovery can apply the concept of biased ligand quantification on a large scale and accelerate the deliberate discovery of novel therapeutics acting via this complex pharmacology.

Decursin enhances TRAIL-induced apoptosis through oxidative stress mediated- endoplasmic reticulum stress signalling in non-small cell lung cancers

BACKGROUND AND PURPOSE

The TNF-related apoptosis-inducing ligand (TRAIL) is a promising anticancer agent due to its remarkable ability to selectively kill tumour cells. However, because most tumours exhibit resistance to TRAIL-induced apoptosis, the development of combination therapies to overcome resistance to TRAIL is required for effective cancer therapy.

EXPERIMENTAL APPROACH

Cell viability and possible synergy between the plant pyranocoumarin decursin and TRAIL was measured by MTT assay and calcusyn software. Reactive oxygen species (ROS) and apoptosis were measured using dichlorodihydrofluorescein and annexin/propidium iodide in cell flow cytometry. Changes in protein levels were assessed with Western blotting.

KEY RESULTS

Combining decursin and TRAIL markedly decreased cell viability and increased apoptosis in TRAIL-resistant non-small-cell lung cancer (NSCLC) cell lines. Decursin induced expression of the death receptor 5 (DR5). Inhibition of DR5 attenuated apoptotic cell death in decursin + TRAIL treated NSCLC cell lines. Interestingly, induction of DR5 and CCAAT/enhancer-binding protein homologues protein by decursin was mediated through selective induction of the pancreatic endoplasmic reticulum kinase (PERK)/activating transcription factor 4 (ATF4) branch of the endoplasmic reticulum stress response pathway. Furthermore, enhancement of PERK/ATF4 signalling by decursin was mediated by ROS generation in NSCLC cell lines, but not in normal human lung cells. Decursin also markedly down-regulated expression of survivin and Bcl-xL in TRAIL-resistant NSCLC cells.

CONCLUSIONS AND IMPLICATIONS

ROS generation by decursin selectively activated the PERK/ATF4 axis of the endoplasmic reticulum stress signalling pathway, leading to enhanced TRAIL sensitivity in TRAIL-resistant NSCLC cell lines, partly via up-regulation of DR5.

The Warburg effect and drug resistance

: The Warburg effect describes the increased utilization of glycolysis rather than oxidative phosphorylation by tumour cells for their energy requirements under physiological oxygen conditions. This effect has been the basis for much speculation on the survival advantage of tumour cells, tumourigenesis and the microenvironment of tumours. More recently, studies have begun to reveal how the Warburg effect could influence drug efficacy and how our understanding of tumour energetics could be exploited to improve drug development. In particular, evidence is emerging demonstrating how better modelling of the tumour metabolic microenvironment could lead to a better prediction of drug efficacy and the identification of new combination strategies. This review will provide details of the current understanding of the complex interplay between glucose metabolism and pharmacology and discuss opportunities for utilizing the Warburg effect in future drug development.

The Concise Guide to PHARMACOLOGY 2015/16: Overview

The Concise Guide to PHARMACOLOGY 2015/16 provides concise overviews of the key properties of over 1750 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.13347/full. This compilation of the major pharmacological targets is divided into eight areas of focus: G protein-coupled receptors, ligand-gated ion channels, voltage-gated ion channels, other ion channels, nuclear hormone receptors, catalytic receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The Concise Guide is published in landscape format in order to facilitate comparison of related targets. It is a condensed version of material contemporary to late 2015, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in the previous Guides to Receptors & Channels and the Concise Guide to PHARMACOLOGY 2013/14. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and GRAC and provides a permanent, citable, point-in-time record that will survive database updates.