Current Medicinal Chemistry - Volume 15, Issue 10, 2008

Cockayne syndrome (complementation groups A and B) is a rare autosomal recessive DNA repair disorder characterized by photosensitive skin and severely impaired physical and intellectual development. The Cockayne syndrome A and B proteins intervene in the repair of DNA modifications that block the RNA polymerase in transcribed DNA sequences (transcription-coupled repair). Recent results suggest that they also have a more general role in the repair of oxidative DNA base modifications. Although the phenotypical consequences of defective repair of oxidatively damaged DNA in Cockayne syndrome are not determined, accumulation of oxidized lesions might contribute to delay the physical and intellectual development of these patients. To conceive new therapeutic strategies for this syndrome, we are investigating whether the oxidatively damaged DNA repair defect in Cockayne syndrome might be complemented by heterologous repair proteins, such as the Escherichia coli formamidopyrimidine-DNA glycosylase and endonuclease III. The complementation studies may shed light on the important lesions for the Cockayne syndrome phenotype and offer new tools for future therapies aimed at counteracting the consequences of oxidatively damaged DNA accumulation.

This review will describe the recent advances in the field of aza-C-nucleosides with a particular emphasis on immucillins and related compounds. The review will cover both chemical and biological aspects concerning their preparation and/or occurrence in Nature as well as their biological properties which include glycosidase, glycosyl transferase, and nucleoside hydrolase and phosphorylase inhibition, among others. These enzymatic inhibitory properties are the basis for the potential use of the title compounds in viral and parasitic infections, cancer and genetic disorders.

The cytokine granulocyte colony-stimulating factor (G-CSF) is produced by numerous cell types including immune and endothelial cells. G-CSF binding to its receptor G-CSF-R which belongs to the cytokine receptor type I family depends on the interaction of alpha-helical motifs of the former and two fibronectin type III as well as an immunoglobulin-like domain of the latter. It activates several signalling transduction pathways including PI3K/Akt, Jak/Stat and MAP kinase, thereby promoting survival, proliferation, differentiation and mobilisation of haematopoietic stem and progenitor cells. Accordingly, recombinant human (rh)G-CSF has been extensively used in clinical haematology and oncology to enable bone marrow transplantation or to treat chemotherapy-associated neutropenia. Using animal models it has been recently shown that G-CSF, alone or in combination with other cytokines such as stem cell factor (SCF), causes an accumulation of bone marrow-derived cells in the infarcted heart which, however, do not differentiate into cardiac cells. Nevertheless, since beneficial effects on structural and functional properties were observed in animal models of cardiac, brain and hindlimb ischaemia other mechanisms of G-CSF action must be operative. Recent evidence suggests paracrine effects mediated by the immigrated bone marrow-derived cells and/or direct effects of the cytokine on resident G-CSF-R expressing cells. In both cases these may include promotion of cellular survival, proliferation and differentiation. First clinical studies in patients with myocardial infarction, heart failure and stroke have been accomplished and are reviewed in this paper.

Adhesion is a hallmark of haematological and solid cancer cells. All five classes of cell adhesion molecules (CAM) - integrins, cadherins, immunoglobulin-like CAMs, selectins and CD44s - are characteristically dysregulated in human cancer. Adhesion enables and promotes cancer-defining biological processes like growth, survival, migration, extravasation, homing, and metastasis. Furthermore, cell adhesion mediates drug resistance (CAM-DR) in multiple myeloma, malignant lymphoma, acute and chronic leukaemias, as well as in pancreatic cancer, neuroblastoma, small cell and non-small cell lung cancer, mesothelioma, colorectal carcinoma, and breast cancer. Cell adhesion protects from death by radiation, genotoxic chemotherapy, or targeted pathway inhibitors. Adhesion molecules are overexpressed on drug resistant cells (e.g. multiple myeloma or prostate cancer). Very recently, several cell adhesion mediated survival pathways have been elucidated, with key mediators being LFA-1, VLA-4, FAK, ILK, Src, PI3K, Akt, Ras, MEK, Erk, HMG-CoA reductase, Rho, Rho kinase, PKC, and NFkB. Because the surface and the intracellular targets are now known and because specific compounds are becoming increasingly available, first clinical trials regarding ANTI-ADHESION therapies are ongoing. However, in comparison to the comprehensive preclinical and clinical knowledge about CAMs, the number of drugs developed thusfar is quite low. ANTIADHESION strategies include targeting of surface antigens, inhibition of cell adhesion associated pathways, inhibition of CAM-DR, and targeted drug delivery. As ANTI-ADHESION is based on general characteristics of cancer cells independent of specific disease entities or treatment modalities, it may become a successful, low-toxic and broadly applicable concept in cancer treatment.

Aggressive immunity characterized by the motion of cytotoxic T lymphocytes (CTLs), T helper (Th) 1 cells, and natural killer (NK) cells is the first line of defense against intracellular microorganism invasion and tumor formation. In patients with infectious diseases and tumors, aggressive immunity is often attenuated by immune suppressive effects provided by regulatory T (Treg) cells including CD4+ CD25+ forkhead-box (fox) p3+ T cells, T regulatory (Tr) 1, Th3, and a subpopulation of γδ-type of T cell receptor-expressing T (γδ T) cells. It has been demonstrated that Treg cells down-regulate aggressive immunity by direct cell interactions and suppressive cytokines (e.g., interleukin (IL)-10, transforming growth factor (TGF)-β). Today, instead of synthesizing chemical agents with serious side effects, protein agents, catalytic oligonucleotides, and natural medicines involved in the elimination of Treg cell-mediated suppressive responses for the restoration of aggressive immunity are expected to be alternatives as a mild clinical remedy against microorganism invasion and tumors.

Arbidol (ARB; ethyl-6-bromo-4-[(dimethylamino)methyl]-5-hydroxy-1-methyl-2-[(phenylthio)methyl]-indole-3-carboxylate hydrochloride monohydrate), is a Russian-made potent broad-spectrum antiviral with demonstrated activity against a number of enveloped and non-enveloped viruses. ARB is well known in Russia and China, although to a lesser extent in western countries. Unlike other broad-spectrum antivirals, ARB has an established molecular mechanism of action against influenza A and B viruses, which is different from that of available influenza antivirals, and a more recently established mechanism of inhibition of hepatitis C virus (HCV). For both viral infections the anti-viral mechanism involves ARB inhibition of virus-mediated fusion with target membrane and a resulting block of virus entry into target cells. However, ARB inhibition of fusion exploits different ARB modalities in case of influenza viruses or HCV. This review aims to summarize the available evidence of ARB effects against different groups of viruses, also, to compare various aspects of ARB anti-fusion mechanisms against influenza virus and HCV (with reference to different stringency of pH-dependence of these two viral fusogens) and to discuss further prospects for ARB and its improved derivatives of the parent compounds.

Endometriosis, a chronic gynecologic disease frequently resulting in chronic pelvic pain, severe dysmenorrhoea, and subfertility, is defined as the presence of endometrial tissue at extrauterine locations, most commonly on the peritoneum and ovaries. Conclusive diagnosis requires laparoscopic surgery followed by histological confirmation. The treatment options -at present- are limited to hormonal therapies and/or surgical ablation of the lesions, and are characterized by high recurrence rates, significant side-effects and limited duration of administration. The pathogenesis of endometriosis is still unclear and numerous immunological and inflammatory factors have been suggested to be involved in the development of the disease, including interleukin (IL)-1, IL-2, IL-6, IL-8, IL-12, tumour necrosis factor -alpha (TNF-α), regulated on activation, normal T-Cell expressed and secreted (RANTES) and its receptor cognate chemokine receptor 1 (CCR1), peroxisome proliferator activated receptors (PPARs), matrix metalloproteinases (MMPs) and cyclooxygenase (COX). Another crucial mechanism in endometriosis is the vascularisation of the endometriotic lesions, with a key role for vascular endothelial growth factor (VEGF). Recently, protease activated receptors (PARs), mitogen-activated protein kinases (MAPKs) and tyrosine kinases have also been associated with the pathophysiology of endometriosis. The aim of this article is to discuss molecules that have recently been found to have connections with the pathogenesis of endometriosis, as potential targets to develop new methods for noninvasive diagnosis and for novel medical management of this disease. This review also critically addresses how these molecules can be tested in basic, preclinical and clinical research, the status of this research and the importance of potential side effects.

Virtual screening (VS) is an important component of cheminformatics and molecular modeling. An abundance of structural information, indicated by both the ever-increasing availability of 3-dimensional (3D) protein structures and the readiness of free conformational databases of commercially available compounds, such as ZINC, supplies a broad platform for VS. At the same time, new technology enables the implementation of more accurate and sophisticated pharmacophore models and the screening of millions of compounds within a manageable period. Therefore, VS is expected to play a more important role in future drug discovery efforts. This paper will examine and compare the advantages and disadvantages of VS against experimental high-throughput screening (HTS). It will also evaluate pharmacophore-based VS against docking-based VS. The strategies leading to successful pharmacophore-based VS are outlined, including how to enumerate a conformational database efficiently, how to select chemical features for a specific pharmacophore model, how to incorporate excluded volumes to enhance the geographical restrictions, and how to optimize a pharmacophore model. Successful examples of pharmacophore-based VS will be presented.

Obesity is a chronic disease characterized by the accumulation of excess adipose tissue associated with an increased risk of multiple morbidities and mortality. At the present time, only three drugs have been approved by the Food and Drug Administration (FDA) for the treatment of obesity. Agonists and antagonists of some of the substances implicated in the regulation of energy homeostasis represent opportunities for anti-obesity drug development. The most promising targets are alpha-melanocyte stimulating hormone (alpha- MSH) receptors, cannabinoid receptors, the 5-hydroxytryptamine (5-HT) receptors and melanin-concentrating hormone (MCH) receptors. MCH receptors could be major potential targets for the treatment of obesity. Many pharmaceutical companies have described MCH-R1 antagonists that have appeared over the past year. Recently, two compounds went into phase I clinical trials that evaluate MCH receptor antagonists as a new perspective for the pharmacologic treatment of obesity. In this review, structure-activity relationships (SAR) in the development of MCH-R1 antagonists are provided.