Novel opportunities for thymidylate metabolism as a therapeutic target

For over 40 years, the fluoropyrimidine 5-fluorouracil (5-FU) has remained the central agent in therapeutic regimens employed in the treatment of colorectal cancer and is frequently combined with the DNA-damaging agents oxaliplatin and irinotecan, increasing response rates and improving overall survival. However, many patients will derive little or no benefit from treatment, highlighting the need to identify novel therapeutic targets to improve the efficacy of current 5-FU-based chemotherapeutic strategies. dUTP nucleotidohydrolase (dUTPase) catalyzes the hydrolysis of dUTP to dUMP and PPi, providing substrate for thymidylate synthase (TS) and DNA synthesis and repair. Although dUTP is a normal intermediate in DNA synthesis, its accumulation and misincorporation into DNA as uracil is lethal. Importantly, uracil misincorporation represents an important mechanism of cytotoxicity induced by the TS-targeted class of chemotherapeutic agents including 5-FU. A growing body of evidence suggests that dUTPase is an important mediator of response to TS-targeted agents. In this article, we present further evidence showing that elevated expression of dUTPase can protect breast cancer cells from the expansion of the intracellular uracil pool, translating to reduced growth inhibition following treatment with 5-FU. We therefore report the implementation of in silico drug development techniques to identify and develop small-molecule inhibitors of dUTPase. As 5-FU and the oral 5-FU prodrug capecitabine remain central agents in the treatment of a variety of malignancies, the clinical utility of a small-molecule inhibitor to dUTPase represents a viable strategy to improve the clinical efficacy of these mainstay chemotherapeutic agents.

Emerging host cell targets for hepatitis C therapy

Chronic hepatitis C virus (HCV) infection is a major burden on humanity. The current HCV therapy has limited efficacy, and there is pressing need for new and more effective therapies. Host cell factors that are required for HCV infection, replication and/or pathogenesis represent potential therapeutic targets. Of particular interest are cellular receptors that mediate HCV entry, factors that facilitate HCV replication and assembly, and intracellular pathways involving lipid biosynthesis, oxidative stress and innate immune response. A crucial challenge now is to manipulate such cellular targets pharmacologically for chronic HCV treatment, without being limited by side effects.

Cognitive dysfunction in depression - pathophysiology and novel targets

Major depressive disorder (MDD) is associated with cognitive dysfunction encompassing several domains, including memory, executive function, processing speed and attention. Cognitive deficits persist in a significant proportion of patients even in remission, compromising psychosocial functioning and workforce performance. While monoaminergic antidepressants may improve cognitive performance in MDD, most antidepressants have limited clinical efficacy. The overarching aims of this review were: (1) to synthesize extant literature on putative biological pathways related to cognitive dysfunction in MDD and (2) to review novel neurotherapeutic targets for cognitive enhancement in MDD. We found that reciprocal and overlapping biological pathways may contribute to cognitive dysfunction in MDD, including an hyperactive hypothalamic-pituitary-adrenal axis, an increase in oxidative and nitrosative stress, inflammation (eg, enhanced production of pro-inflammatory cytokines), mitochondrial dysfunction, increased apoptosis as well as a diminished neurotrophic support. Several promising neurotherapeutic targets were identified such as minocycline, statins, anti-inflammatory compounds, N-acetylcysteine, omega-3 poliunsaturated fatty acids, erythropoietin, thiazolidinediones, glucagon-like peptide-1 analogues, S-adenosyl-l-methionine (SAMe), cocoa flavonols, creatine monohydrate and lithium. Erythropoietin and SAMe had pro-cognitive effects in randomized controlled trials (RCT) involving MDD patients. Despite having preclinical and/or preliminary evidences from trials suggesting possible efficacy as novel cognitive enhancing agents for MDD, no RCT to date was performed for most of the other therapeutic targets reviewed herein. In conclusion, multiple biological pathways are involved in cognitive dysfunction in MDD. RCTs testing genuinely novel pro-cognitive compounds for MDD are warranted.

A glycolytic phenotype is associated with prostate cancer progression and aggressiveness: a role for monocarboxylate transporters as metabolic targets for therapy

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The phosphoinositide 3-kinase signaling pathway as a therapeutic target in grade IV brain tumors

Brain tumors comprise a wide variety of neoplasia classified according to their cellular origin and their morphological and histological characteristics. The transformed phenotype of brain tumor cells has been extensively studied in the past years, achieving a significant progress in our understanding of the molecular pathways leading to tumorigenesis. It has been reported that the phosphoinositide 3-kinase (PI3K)/AKT signaling pathway is frequently altered in grade IV brain tumors resulting in uncontrolled cell growth, survival, proliferation, angiogenesis, and migration. This aberrant activation can be explained by oncogenic mutations in key components of the pathway or through abnormalities in its regulation. These alterations include overexpression and mutations of receptor tyrosine kinases (RTKs), mutations and deletions of the phosphatase and tensin homologue deleted on chromosome 10 (PTEN) tumor suppressor gene, encoding a lipid kinase that directly antagonized PI3K activity, and alterations in Ras signaling. Due to promising results of preclinical studies investigating the PI3K/AKT pathway in grade IV brain tumors like glioblastoma and medulloblastoma, the components of this pathway have emerged as promising therapeutic targets to treat these malignant brain tumors. Although an arsenal of small molecule inhibitors that target specific components of this signaling pathway is being developed, its successful application in the clinics remains a challenge. In this article we will review the molecular basis of the PI3K/AKT signaling pathway in malignant brain tumors, mainly focusing on glioblastoma and medulloblastoma, and we will further discuss the current status and potential of molecular targeted therapies.

Targets of emerging therapies for viral hepatitis B and C

Viral hepatitis B and C, structurally two completely different viruses, commonly infect human hepatocytes and cause similar clinical manifestations. Since their discovery, IFN has been a pillar in the treatment. However, because of the different natures of the viruses, therapeutic approaches diverge and new treatment targets are tailored specifically for each virus. Herein, the authors analyse therapeutic approaches for hepatitis B virus (HBV) and hepatitis C virus (HCV) and focus on emerging concepts that are under clinical evaluation. In particular, promising viral inhibitors for HBV and HCV are reviewed and the current status of research for gene therapy for HCV is described. Immune therapy is a fast-moving field with fascinating results which include therapeutic vaccines and toll-like receptor agonists that could improve tomorrow's treatment approaches.

Kinase signalling pathways in endometriosis: potential targets for non-hormonal therapeutics.

BACKGROUND Endometriosis, the growth of endometrial tissue outside the uterine cavity, is associated with chronic pelvic pain, subfertility and an increased risk of ovarian cancer. Current treatments include the surgical removal of the lesions or the induction of a hypoestrogenic state. However, a reappearance of the lesion after surgery is common and a hypoestrogenic state is less than optimal for women of reproductive age. Additional approaches are required. Endometriosis lesions exist in a unique microenvironment characterized by increased concentrations of hormones, inflammation, oxidative stress and iron. This environment influences cell survival through the binding of membrane receptors and a subsequent cascading activation of intracellular kinases that stimulate a cellular response. Many of these kinase signalling pathways are constitutively activated in endometriosis. These pathways are being investigated as therapeutic targets in other diseases and thus may also represent a target for endometriosis treatment. METHODS To identify relevant English language studies published up to 2015 on kinase signalling pathways in endometriosis, we searched the Pubmed database using the following search terms in various combinations; 'endometriosis', 'inflammation', 'oxidative stress', 'iron', 'kinase', 'NF kappa', 'mTOR', 'MAPK' 'p38', 'JNK', 'ERK' 'estrogen' and progesterone'. Further citing references were identified using the Scopus database and finally current clinical trials were searched on the clinicaltrials.gov trial registry. RESULTS The current literature on intracellular kinases activated by the endometriotic environment can be summarized into three main pathways that could be targeted for treatments: the canonical IKKβ/NFκB pathway, the MAPK pathways (ERK1/2, p38 and JNK) and the PI3K/AKT/mTOR pathway. A number of pharmaceutical compounds that target these pathways have been successfully trialled in in vitro and animal models of endometriosis, although they have not yet proceeded to clinical trials. The current generation of kinase inhibitors carry a potential for adverse side effects. CONCLUSIONS Kinase signalling pathways represent viable targets for endometriosis treatment. At present, however, further improvements in clinical efficacy and the profile of adverse effects are required before these compounds can be useful for long-term endometriosis treatment. A better understanding of the molecular activity of these kinases, including the specific extracellular compounds that lead to their activation in endometriotic cells specifically should facilitate their improvement and could potentially lead to new, non-hormonal treatments of endometriosis.

FGFR1 emerges as a potential therapeutic target for lobular breast carcinomas

Purpose: Classic lobular carcinomas (CLC) account for 10% to 15% of all breast cancers. At the genetic level, CLCs show recurrent physical loss of chromosome16q coupled with the lack of E-cadherin (CDH1 gene) expression. However, little is known about the putative therapeutic targets for these tumors. The aim of this study was to characterize CLCs at the molecular genetic level and identify putative therapeutic targets. Experimental Design: We subjected 13 cases of CLC to a comprehensive molecular analysis including immunohistochemistry for E-cadherin, estrogen and progesterone receptors, HER2/ neu and p53; high-resolution comparative genomic hybridization (HR-CGH); microarray-based CGH (aCGH); and fluorescent and chromogenic in situ hybridization for CCND1 and FGFR1. Results: All cases lacked the expression of E-cadherin, p53, and HER2, and all but one case was positive for estrogen receptors. HR-CGH revealed recurrent gains on 1q and losses on 16q (both, 85%). aCGH showed a good agreement with but higher resolution and sensitivity than HR-CGH. Recurrent, high level gains at 11q13 (CCND1) and 8p12-p11.2 were identified in seven and six cases, respectively, and were validated with in situ hybridization. Examination of aCGH and the gene expression profile data of the cell lines, MDA-MB-134 and ZR-75-1, which harbor distinct gains of 8p12-p11.2, identified FGFR1 as a putative amplicon driver of 8p12-p11.2 amplification in MDA-MB-134. Inhibition of FGFR1 expression using small interfering RNA or a small-molecule chemical inhibitor showed that FGFR1 signaling contributes to the survival of MDA-MB-134 cells. Conclusions: Our findings suggest that receptor FGFR1 inhibitors may be useful as therapeutics in a subset of CLCs.

Neurodegeneration is an early event in diabetic retinopathy:therapeutic implications

Diabetic retinopathy (DR) remains the leading cause of blindness among working-age individuals in developed countries. Current treatments for DR are indicated in advanced stages of the disease and are associated with significant adverse effects. Therefore, new pharmacological treatments for the early stages of DR are needed. DR has been classically considered to be a microcirculatory disease of the retina. However, there is growing evidence to suggest that retinal neurodegeneration is an early event in the pathogenesis of DR, which participates in the microcirculatory abnormalities that occur in DR. Therefore, the study of the underlying mechanisms that lead to neurodegeneration will be essential for identifying new therapeutic targets. From the clinical point of view, the identification of those patients in whom retinal neurodegeneration appears will be crucial for implementing early treatment based on neuroprotective drugs. When the early stages of DR are the therapeutic target, it would be inconceivable to recommend an aggressive treatment such as intravitreous injections. By contrast, topical administration of neuroprotective drugs by using eye drops is a possible option. However, clinical trials to determine the safety and effectiveness of this non-invasive route, as well as a standardisation of the methods for monitoring neurodegeneration, are needed.

Rho-kinase as a therapeutic target in vascular diseases:striking nitric oxide signaling

Rho GTPases are a globular, monomeric group of small signaling G-protein molecules. Rho-associated protein kinase/Rho-kinase (ROCK) is a downstream effector protein of the Rho GTPase. Rho-kinases are the potential therapeutic targets in the treatment of cardiovascular diseases. Here, we have primarily discussed the intriguing roles of ROCK in cardiovascular health in relation to nitric oxide signaling. Further, we highlighted the biphasic effects of Y-27632, a ROCK inhibitor under shear stress, which acts as an agonist of nitric oxide production in endothelial cells. The biphasic effects of this inhibitor raised the question of safety of the drug usage in treating cardiovascular diseases.

MiRNA 34a: a therapeutic target for castration-resistant prostate cancer

INTRODUCTION: Development of a therapy for bone metastases is of paramount importance for castration-resistant prostate cancer (CRPC). The osteomimetic properties of CRPC confer a propensity to metastasize to osseous sites. Micro-ribonucleic acid (miRNA) is non-coding RNA that acts as a post-transcriptional regulator of multiple proteins and associated pathways. Therefore identification of miRNAs could reveal a valid third generation therapy for CRPC. Areas covered: miR34a has been found to play an integral role in the progression of prostate cancer, particularly in the regulation of metastatic genes involved in migration, intravasation, extravasation, bone attachment and bone homeostasis. The correlation between miR34a down-regulation and metastatic progression has generated substantial interest in this field. Expert opinion: Examination of the evidence reveals that miR34a is an ideal target for gene therapy for metastatic CRPC. We also conclude that future studies should focus on the effects of miR34a upregulation in CRPC with respect to migration, translocation to bone micro-environment and osteomimetic phenotype development. The success of miR34a as a therapeutic is reliant on the development of appropriate delivery systems and targeting to the bone micro-environment. In tandem with any therapeutic studies, biomarker serum levels should also be ascertained as an indicator of successful miR34a delivery.

Fibroblast growth factors:new insights, new targets in the management of diabetes

The fibroblast growth factor (FGF) family consists of 22 evolutionarily and structurally related proteins (FGF1 to FGF23; with FGF15 being the rodent ortholog of human FGF19). Based on their mechanism of action, FGFs can be categorized into intracrine, autocrine/paracrine and endocrine subgroups. Both autocrine/paracrine and endocrine FGFs are secreted from their cells of origin and exert their effects on target cells by binding to and activating specific single-pass transmembrane tyrosine kinase receptors (FGFRs). Moreover, FGF binding to FGFRs requires specific cofactors, namely heparin/heparan sulfate proteoglycans or Klothos for autocrine/paracrine and endocrine FGF signaling, respectively. FGFs are vital for embryonic development and mediate a broad spectrum of biological functions, ranging from cellular excitability to angiogenesis and tissue regeneration. Over the past decade certain FGFs (e.g. FGF1, FGF10, FGF15/FGF19 and FGF21) have been further recognized as regulators of energy homeostasis, metabolism and adipogenesis, constituting novel therapeutic targets for obesity and obesity-related cardiometabolic disease. Until recently, translational research has been mainly focused on FGF21, due to the pleiotropic, beneficial metabolic actions and the relatively benign safety profile of its engineered variants. However, increasing evidence regarding the role of additional FGFs in the regulation of metabolic homeostasis and recent developments regarding novel, engineered FGF variants have revitalized the research interest into the therapeutic potential of certain additional FGFs (e.g. FGF1 and FGF15/FGF19). This review presents a brief overview of the FGF family, describing the mode of action of the different FGFs subgroups, and focuses on FGF1 and FGF15/FGF19, which appear to also represent promising new targets for the treatment of obesity and type 2 diabetes.

The epigenome as a therapeutic target for Parkinson's disease

Parkinson’s disease (PD) is a common, progressive neurodegenerative disease characterised by degeneration of nigrostriatal dopaminergic neurons, aggregation of α-synuclein and motor symptoms. Current dopamine-replacement strategies provide symptomatic relief, however their effectiveness wear off over time and their prolonged use leads to disabling side-effects in PD patients. There is therefore a critical need to develop new drugs and drug targets to protect dopaminergic neurons and their axons from degeneration in PD. Over recent years, there has been robust evidence generated showing that epigenetic dysregulation occurs in PD patients, and that epigenetic modulation is a promising therapeutic approach for PD. This article first discusses the present evidence implicating global, and dopaminergic neuron-specific, alterations in the methylome in PD, and the therapeutic potential of pharmacologically targeting the methylome. It then focuses on another mechanism of epigenetic regulation, histone acetylation, and describes how the histone acetyltransferase (HAT) and histone deacetylase (HDAC) enzymes that mediate this process are attractive therapeutic targets for PD. It discusses the use of activators and/or inhibitors of HDACs and HATs in models of PD, and how these approaches for the selective modulation of histone acetylation elicit neuroprotective effects. Finally, it outlines the potential of employing small molecule epigenetic modulators as neuroprotective therapies for PD, and the future research that will be required to determine and realise this therapeutic potential.

SNP technologies for drug discovery : a current review

Single nucleotide polymorphisms (SNPs) are unique genetic differences between individuals that contribute in significant ways to the determination of human variation including physical characteristics like height and appearance as well as less obvious traits such as personality, behaviour and disease susceptibility. SNPs can also significantly influence responses to pharmacotherapy and whether drugs will produce adverse reactions. The development of new drugs can be made far cheaper and more rapid by selecting participants in drug trials based on their genetically determined response to drugs. Technology that can rapidly and inexpensively genotype thousands of samples for thousands of SNPs at a time is therefore in high demand. With the completion of the human genome project, about 12 million true SNPs have been identified to date. However, most have not yet been associated with disease susceptibility or drug response. Testing for the appropriate drug response SNPs in a patient requiring treatment would enable individualised therapy with the right drug and dose administered correctly the first time. Many pharmaceutical companies are also interested in identifying SNPs associated with polygenic traits so novel therapeutic targets can be discovered. This review focuses on technologies that can be used for genotyping known SNPs as well as for the discovery of novel SNPs associated with drug response.

Translating tissue engineering technology platforms into cancer research

Technology platforms originally developed for tissue engineering applications produce valuable models that mimic three-dimensional (3D) tissue organization and function to enhance the understanding of cell/tissue function under normal and pathological situations. These models show that when replicating physiological and pathological conditions as closely as possible investigators are allowed to probe the basic mechanisms of morphogenesis, differentiation and cancer. Significant efforts investigating angiogenetic processes and factors in tumorigenesis are currently undertaken to establish ways of targeting angiogenesis in tumours. Anti-angiogenic agents have been accepted for clinical application as attractive targeted therapeutics for the treatment of cancer. Combining the areas of tumour angiogenesis, combination therapies and drug delivery systems is therefore closely related to the understanding of the basic principles that are applied in tissue engineering models. Studies with 3D model systems have repeatedly identified complex interacting roles of matrix stiffness and composition, integrins, growth factor receptors and signalling in development and cancer. These insights suggest that plasticity, regulation and suppression of these processes can provide strategies and therapeutic targets for future cancer therapies. The historical perspective of the fields of tissue engineering and controlled release of therapeutics, including inhibitors of angiogenesis in tumours is becoming clearly evident as a major future advance in merging these fields. New delivery systems are expected to greatly enhance the ability to deliver drugs locally and in therapeutic concentrations to relevant sites in living organisms. Investigating the phenomena of angiogenesis and anti-angiogenesis in 3D in vivo models such as the Arterio-Venous (AV) loop mode in a separated and isolated chamber within a living organism adds another significant horizon to this perspective and opens new modalities for translational research in this field.