Annual Review of Pharmacology and Toxicology - Volume 54, 2014
Volume 54, 2014
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Learning to Program the Liver
Vol. 54 (2014), pp. 1–8More LessHalf a century ago, people were learning to program computers. Similarly, we have been trying to learn how to program the liver to protect us from chemicals. We have given various chemicals that activate transcription factors such as the nuclear receptors: These ligand-activated nuclear receptors enter the nucleus of liver cells (hepatocytes) and bind to their specific motifs in DNA to increase the transcription of various genes that protect against chemical-induced injury. Several examples from our laboratory are given to demonstrate this detoxification process: (a) a steroid chemical that increases the expression of a hepatic transporter to enhance the elimination of other chemicals and thus decrease their toxicity, (b) a metal that decreases its own toxicity by increasing the production of a protein to which it binds, and (c) an herbal chemical that activates a transcription factor that serves as a sensor of oxidative stress and electrophiles to protect against cytotoxicity by increasing the expression of numerous antioxidant proteins. In addition, at the present time, we are investigating which bile acids that are synthesized in the liver and altered by bacteria in the intestine may be used to alter the programming of the liver, as well as how the liver reprograms itself after birth in the transition from a hematopoietic organ to one that decreases the toxicity of chemicals.
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The Druggable Genome: Evaluation of Drug Targets in Clinical Trials Suggests Major Shifts in Molecular Class and Indication
Vol. 54 (2014), pp. 9–26More LessThe largest innovations within pharmaceutical development come through new compounds that have unique and novel modes of action. These innovations commonly involve expanding the protein space targeted by pharmaceutical agents. At present, information about drugs and drug targets is available online via public databases such as DrugBank and the Therapeutic Targets Database. However, this information is biased, understandably so, toward established drugs and drug-target interactions. To gain a better overview of the drug-targeted portion of the human proteome and the directions of current drug development, we developed a data set of clinical trial drug-target interactions based on CenterWatch's Drugs in Clinical Trials Database, one of the largest databases of its kind. Our curation identified 475 potentially novel clinical trial drug targets. This review aims to identify trends in drug development based on the potentially novel targets currently being explored in clinical trials.
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Engineered Botulinum Neurotoxins as New Therapeutics
Vol. 54 (2014), pp. 27–51More LessBotulinum neurotoxins (BoNTs) cause flaccid paralysis by inhibiting neurotransmission at cholinergic nerve terminals. Each BoNT consists of three domains that are essential for toxicity: the binding domain, the translocation domain, and the catalytic light-chain domain. BoNT modular architecture is associated with a multistep mechanism that culminates in the intracellular proteolysis of SNARE (soluble N-ethylmaleimide-sensitive-fusion-protein attachment protein receptor) proteins, which prevents synaptic vesicle exocytosis. As the most toxic proteins known, BoNTs have been extensively studied and are used as pharmaceutical agents to treat an increasing variety of disorders. This review summarizes the level of sophistication reached in BoNT engineering and highlights the diversity of approaches taken to utilize the modularity of the toxin. Improved efficiency and applicability have been achieved by direct mutagenesis and interserotype domain rearrangement. The scope of BoNT activity has been extended to nonneuronal cells and offers the basis for novel biomolecules in the treatment of secretion disorders.
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Pharmacometrics in Pregnancy: An Unmet Need
Vol. 54 (2014), pp. 53–69More LessPregnant women and their fetuses are orphan populations with respect to the safety and efficacy of drugs. Physiological and absorption, distribution, metabolism, and excretion (ADME) changes during pregnancy can significantly affect drug pharmacokinetics (PK) and may necessitate dose adjustment. Here, the specific aspects related to the design, execution, and analysis of clinical studies in pregnant women are discussed, underlining the unmet need for top-down pharmacometrics analyses and bottom-up modeling approaches. The modeling tools that support data analysis for the pregnancy population are reviewed, with a focus on physiologically based pharmacokinetics (PBPK) and population pharmacokinetics (POP-PK). By integrating physiological data, preclinical data, and clinical data (e.g., via POP-PK) to quantify anticipated changes in the PK of drugs during pregnancy, the PBPK approach allows extrapolation beyond the previously studied model drugs to other drugs with well-characterized ADME characteristics. Such a systems pharmacology approach can identify drugs whose PK may be altered during pregnancy, guide rational PK study design, and support dose adjustment for pregnant women.
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Antiparasitic Chemotherapy: From Genomes to Mechanisms
Vol. 54 (2014), pp. 71–94More LessOwing to the absence of antiparasitic vaccines and the constant threat of drug resistance, the development of novel antiparasitic chemotherapies remains of major importance for disease control. A better understanding of drug transport (uptake and efflux), drug metabolism and the identification of drug targets, and mechanisms of drug resistance would facilitate the development of more effective therapies. Here, we focus on malaria and African trypanosomiasis. We review existing drugs and drug development, emphasizing high-throughput genomic and genetic approaches, which hold great promise for elucidating antiparasitic mechanisms. We describe the approaches and technologies that have been influential for each parasite and develop new ideas for future research directions, including mode-of-action studies for drug target deconvolution.
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Targeting Multidrug Resistance Protein 1 (MRP1, ABCC1): Past, Present, and Future
Vol. 54 (2014), pp. 95–117More LessThe human ATP-binding cassette transporter multidrug resistance protein 1 (MRP1), encoded by ABCC1, was initially identified because of its ability to confer multidrug resistance in lung cancer cells. It is now established that MRP1 plays a role in protecting certain tissues from xenobiotic insults and that it mediates the cellular efflux of the proinflammatory cysteinyl leukotriene C4 as well as a vast array of other endo- and xenobiotic organic anions. Many of these are glutathione (GSH) or glucuronide conjugates, the products of Phase II drug metabolism. MRP1 also plays a role in the cellular efflux of the reduced and oxidized forms of GSH and thus contributes to the many physiological and pathophysiological processes influenced by these small peptides, including oxidative stress. In this review, the pharmacological and physiological aspects of MRP1 are considered in the context of the current status and future prospects of pharmacological and genetic modulation of MRP1 activity.
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Glutamate Receptor Antagonists as Fast-Acting Therapeutic Alternatives for the Treatment of Depression: Ketamine and Other Compounds
Vol. 54 (2014), pp. 119–139More LessThe N-methyl-d-aspartate (NMDA) receptor antagonist ketamine has rapid and potent antidepressant effects in treatment-resistant major depressive disorder and bipolar depression. These effects are in direct contrast to the more modest effects seen after weeks of treatment with classic monoaminergic antidepressants. Numerous open-label and case studies similarly validate ketamine's antidepressant properties. These clinical findings have been reverse-translated into preclinical models in an effort to elucidate ketamine's antidepressant mechanism of action, and three important targets have been identified: mammalian target of rapamycin (mTOR), eukaryotic elongation factor 2 (eEF2), and glycogen synthase kinase-3 (GSK-3). Current clinical and preclinical research is focused on (a) prolonging/maintaining ketamine's antidepressant effects, (b) developing more selective NMDA receptor antagonists free of ketamine's adverse effects, and (c) identifying predictor, mediator/moderator, and treatment response biomarkers of ketamine's antidepressant effects.
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Environmental Toxins and Parkinson's Disease
Vol. 54 (2014), pp. 141–164More LessParkinson's disease (PD) is a chronic, progressive, disabling neurodegenerative disorder that begins in mid to late life and is characterized by motor impairment, autonomic dysfunction, and, in many, psychological and cognitive changes. Recent advances have helped delineate pathogenetic mechanisms, yet the cause of PD in most individuals is unknown. Although at least 15 genes and genetic loci have been associated with PD, identified genetic causes are responsible for only a few percent of cases. Epidemiologic studies have found increased risk of PD associated with exposure to environmental toxicants such as pesticides, solvents, metals, and other pollutants, and many of these compounds recapitulate PD pathology in animal models. This review summarizes the environmental toxicology of PD, highlighting the consistency of observations across cellular, animal, and human studies of PD pathogenesis.
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Drugs for Allosteric Sites on Receptors
Vol. 54 (2014), pp. 165–184More LessThe presence of druggable, topographically distinct allosteric sites on a wide range of receptor families has offered new paradigms for small molecules to modulate receptor function. Moreover, ligands that target allosteric sites offer significant advantages over the corresponding orthosteric ligands in terms of selectivity, including subtype selectivity within receptor families, and can also impart improved physicochemical properties. However, allosteric ligands are not a panacea. Many chemical issues (e.g., flat structure-activity relationships) and pharmacological issues (e.g., ligand-biased signaling) that are allosteric centric have emerged. Notably, the fact that allosteric sites are less evolutionarily conserved leads to improved selectivity; however, this can also lead to species differences that can hinder safety assessment. Many allosteric ligands possess molecular switches, wherein a small structural change (chemical or metabolic) can modulate the mode of pharmacology or receptor subtype selectivity. As the field has matured, as described here, key principles and strategies have emerged for the design of ligands/drugs for allosteric sites.
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microRNA Therapeutics in Cardiovascular Disease Models
Seema Dangwal, and Thomas ThumVol. 54 (2014), pp. 185–203More LessCardiovascular diseases are a major cause of human morbidity and mortality, posing a high socioeconomic burden on the health sector worldwide. microRNAs (miRNAs) constitute a new class of unique molecular regulators involved in the pathophysiology of a wide range of disorders. Studies in the past decade have identified miRNA signatures of various cardiovascular disorders and successfully validated miRNA-based therapeutic options in various small and a few large experimental cardiovascular disease models. In these models, researchers manipulate the expression of miRNAs and downstream signaling cascades, aiming to prevent and cure cardiovascular disease. Here, we review and discuss the recent reports on the in vivo use of miRNA animal models and miRNA therapeutic development as well as provide an outlook for clinical applications in the near future.
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Nanocarriers for Vascular Delivery of Anti-Inflammatory Agents
Vol. 54 (2014), pp. 205–226More LessThere is a need for improved treatment of acute vascular inflammation in conditions such as ischemia-reperfusion injury, acute lung injury, sepsis, and stroke. The vascular endothelium represents an important therapeutic target in these conditions. Furthermore, some anti-inflammatory agents (AIAs) (e.g., biotherapeutics) require precise delivery into subcellular compartments. In theory, optimized delivery to the desired site of action may improve the effects and enable new mechanisms of action of these AIAs. Diverse nanocarriers (NCs) and strategies for targeting them to endothelial cells have been designed and explored for this purpose. Studies in animal models suggest that delivery of AIAs using NCs may provide potent and specific molecular interventions in inflammatory pathways. However, the industrial development and clinical translation of complex NC-AIA formulations are challenging. Rigorous analysis of therapeutic/side effect and benefit/cost ratios is necessary to identify and optimize the approaches that may find clinical utility in the management of acute inflammation.
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G Protein–Coupled Receptors Revisited: Therapeutic Applications Inspired by Synthetic Biology
Vol. 54 (2014), pp. 227–249More LessG protein–coupled receptors (GPCRs) mediate the majority of cellular responses to hormones and neurotransmitters within the human body. They have much potential in the emerging field of synthetic biology, which is the rational, systematic design of biological systems with desired functionality. The responsiveness of GPCRs to a plethora of endogenous and exogenous ligands and stimuli make them ideal sensory receptor modules of synthetic gene networks. Such networks can activate target gene expression in response to a specific stimulus. Additionally, because GPCRs are important pharmacological targets of various human diseases, genes encoding their protein/peptide ligands can also be incorporated as target genes of the response output elements of synthetic gene networks. This review aims to critically examine the potential role of GPCRs in constructing therapeutic synthetic gene networks and to discuss various challenges in utilizing GPCRs for synthetic biology applications.
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Cause and Consequence of Cancer/Testis Antigen Activation in Cancer
Vol. 54 (2014), pp. 251–272More LessTumor cells frequently exhibit widespread epigenetic aberrations that significantly alter the repertoire of expressed proteins. In particular, it has been known for nearly 25 years that tumors frequently reactivate genes whose expression is typically restricted to germ cells. These gene products are classified as cancer/testis antigens (CTAs) owing to their biased expression pattern and their immunogenicity in cancer patients. While these genes have been pursued as targets for anticancer vaccines, whether these reactivated testis proteins have roles in supporting tumorigenic features is less studied. Recent evidence now indicates that these proteins can be directly employed by the tumor cell regulatory environment to support cell-autonomous behaviors. Here, we review the history of the CTA field and present recent findings indicating that CTAs can play functional roles in supporting tumorigenesis.
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Targeting PCSK9 for Hypercholesterolemia
Vol. 54 (2014), pp. 273–293More LessDyslipidemias are a predominant risk factor for cardiovascular disease. Biological and genetic research has led to the identification of several genes and proteins that may be pharmacologically targeted to improve lipoprotein profiles and possibly cardiovascular outcomes in patients with dyslipidemia. The observation that proprotein convertase subtilisin/kexin type 9 (PCSK9) regulates the levels of circulating low-density lipoprotein C (LDL-C) by enhancing the degradation of the hepatic low-density lipoprotein receptor (LDLR) prompted the search for drugs that inhibit PCSK9 activity. Several approaches to inhibiting PCSK9 activity have been proposed; these involve inhibitory antibodies, small molecules, and gene silencing. To date, the most promising and advanced approach relates to monoclonal antibodies, which can decrease LDL cholesterol by 65–70%, even as an add-on therapy to a maximal dose of a statin. Phase III studies and large, event-driven clinical trials are ongoing and will fully address the viability and role of these drugs in clinical practice.
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Fetal and Perinatal Exposure to Drugs and Chemicals: Novel Biomarkers of Risk
Vol. 54 (2014), pp. 295–315More LessPregnant women are almost always excluded from randomized controlled clinical trials, as the risks to the fetus posed by most new chemical entities or approved drugs cannot be sufficiently ruled out. Hence, a major scientific challenge in this field is to discover and validate alternative tools that will fill the knowledge gap created by the lack of participation in gold-standard randomized trials. This review focuses on novel tools that allow estimation of fetal risks after exposure to therapeutic agents, such as placental perfusion studies, biomarkers of fetal exposure, and novel epidemiological and pharmacogenetic tools, all of which have been tested successfully in recent years.
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Sodium Channels, Inherited Epilepsy, and Antiepileptic Drugs
Vol. 54 (2014), pp. 317–338More LessVoltage-gated sodium channels initiate action potentials in brain neurons, mutations in sodium channels cause inherited forms of epilepsy, and sodium channel blockers—along with other classes of drugs—are used in therapy of epilepsy. A mammalian voltage-gated sodium channel is a complex containing a large, pore-forming α subunit and one or two smaller β subunits. Extensive structure-function studies have revealed many aspects of the molecular basis for sodium channel structure, and X-ray crystallography of ancestral bacterial sodium channels has given insight into their three-dimensional structure. Mutations in sodium channel α and β subunits are responsible for genetic epilepsy syndromes with a wide range of severity, including generalized epilepsy with febrile seizures plus (GEFS+), Dravet syndrome, and benign familial neonatal-infantile seizures. These seizure syndromes are treated with antiepileptic drugs that offer differing degrees of success. The recent advances in understanding of disease mechanisms and sodium channel structure promise to yield improved therapeutic approaches.
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Chronopharmacology: New Insights and Therapeutic Implications
Vol. 54 (2014), pp. 339–361More LessMost facets of mammalian physiology and behavior vary according to time of day, thanks to endogenous circadian clocks. Therefore, it is not surprising that many aspects of pharmacology and toxicology also oscillate according to the same 24-h clocks. Daily oscillations in abundance of proteins necessary for either drug absorption or metabolism result in circadian pharmacokinetics, and oscillations in the physiological systems targeted by these drugs result in circadian pharmacodynamics. These clocks are present in most cells of the body, organized in a hierarchical fashion. Interestingly, some aspects of physiology and behavior are controlled directly via a “master clock” in the suprachiasmatic nuclei of the hypothalamus, whereas others are controlled by “slave” oscillators in separate brain regions or body tissues. Recent research shows that these clocks can respond to different cues and thereby show different phase relationships. Therefore, full prediction of chronopharmacology in pathological contexts will likely require a systems biology approach that considers chronointeractions among different clock-regulated systems.
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Small-Molecule Allosteric Activators of Sirtuins
Vol. 54 (2014), pp. 363–380More LessThe mammalian sirtuins (SIRT1–7) are NAD+-dependent lysine deacylases that play central roles in cell survival, inflammation, energy metabolism, and aging. Members of this family of enzymes are considered promising pharmaceutical targets for the treatment of age-related diseases including cancer, type 2 diabetes, inflammatory disorders, and Alzheimer's disease. SIRT1-activating compounds (STACs), which have been identified from a variety of chemical classes, provide health benefits in animal disease models. Recent data point to a common mechanism of allosteric activation by natural and synthetic STACs that involves the binding of STACs to a conserved N-terminal domain in SIRT1. Compared with polyphenols such as resveratrol, the synthetic STACs show greater potency, solubility, and target selectivity. Although considerable progress has been made regarding SIRT1 allosteric activation, key questions remain, including how the molecular contacts facilitate SIRT1 activation, whether other sirtuin family members will be amenable to activation, and whether STACs will ultimately prove safe and efficacious in humans.
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Emerging Therapeutics for Alzheimer's Disease
Vol. 54 (2014), pp. 381–405More LessDespite decades of intense research, therapeutics for Alzheimer's disease (AD) are still limited to symptomatic treatments that possess only short-term efficacy. Recently, several large-scale Phase III trials targeting amyloid-β production or clearance have failed to show efficacy, leading to a reexamination of the amyloid hypothesis as well as highlighting the need to explore alternatives in both clinical testing strategies and drug discovery targets. In this review, we discuss therapeutics currently being tested in clinical trials and up-and-coming interventions that have shown promise in animal models, devoting attention to the mechanisms that may underlie their ability to influence disease progression and placing particular emphasis on tau therapeutics.
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Free Fatty Acid (FFA) and Hydroxy Carboxylic Acid (HCA) Receptors
Vol. 54 (2014), pp. 407–434More LessSaturated and unsaturated free fatty acids (FFAs), as well as hydroxy carboxylic acids (HCAs) such as lactate and ketone bodies, are carriers of metabolic energy, precursors of biological mediators, and components of biological structures. However, they are also able to exert cellular effects through G protein–coupled receptors named FFA1–FFA4 and HCA1–HCA3. Work during the past decade has shown that these receptors are widely expressed in the human body and regulate the metabolic, endocrine, immune and other systems to maintain homeostasis under changing dietary conditions. The development of genetic mouse models and the generation of synthetic ligands of individual FFA and HCA receptors have been instrumental in identifying cellular and biological functions of these receptors. These studies have produced strong evidence that several FFA and HCA receptors can be targets for the prevention and treatment of various diseases, including type 2 diabetes mellitus, obesity, and inflammation.
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Previous Volumes
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Volume 65 (2025)
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Volume 64 (2024)
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Volume 63 (2023)
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Volume 62 (2022)
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Volume 61 (2021)
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Volume 60 (2020)
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Volume 59 (2019)
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Volume 58 (2018)
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Volume 57 (2017)
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Volume 56 (2016)
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Volume 55 (2015)
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Volume 54 (2014)
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Volume 53 (2013)
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Volume 52 (2012)
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Volume 51 (2011)
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Volume 50 (2010)
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Volume 49 (2009)
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Volume 48 (2008)
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Volume 47 (2007)
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Volume 46 (2006)
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Volume 45 (2005)
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Volume 44 (2004)
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Volume 43 (2003)
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Volume 42 (2002)
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Volume 41 (2001)
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Volume 40 (2000)
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Volume 39 (1999)
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Volume 38 (1998)
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Volume 37 (1997)
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Volume 36 (1996)
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Volume 35 (1995)
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Volume 34 (1994)
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Volume 33 (1993)
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Volume 32 (1992)
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Volume 31 (1991)
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Volume 30 (1990)
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Volume 29 (1989)
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Volume 28 (1988)
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Volume 27 (1987)
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Volume 26 (1986)
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Volume 25 (1985)
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Volume 24 (1984)
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Volume 23 (1983)
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Volume 22 (1982)
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Volume 21 (1981)
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Volume 20 (1980)
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Volume 19 (1979)
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Volume 18 (1978)
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Volume 17 (1977)
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Volume 16 (1976)
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Volume 15 (1975)
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Volume 14 (1974)
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Volume 13 (1973)
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Volume 12 (1972)
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Volume 11 (1971)
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Volume 10 (1970)
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Volume 9 (1969)
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Volume 8 (1968)
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Volume 7 (1967)
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Volume 6 (1966)
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Volume 5 (1965)
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Volume 4 (1964)
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Volume 3 (1963)
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Volume 2 (1962)
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Volume 1 (1961)
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Volume 0 (1932)