Current Medicinal Chemistry (v.20, #9)
Cellular Signaling Crosstalk Between Multiple Receptors for Investigation of Pathophysiology in Multifactorial Diseases - What is Clinically-Relevant Crosstalk? by T. Yoshikawa, H. Kanazawa (1091-1102).
Recently, genomics and proteomics have been utilized as advanced tools for investigation of cellular signaling pathways and molecular interactions, and elucidated promiscuous networks composed of numerous interactions among pathways. However, some of these interactions are considered to be simply contributing to background ‘noise’ and others are as ‘crosstalk’ biologically-relevant to cellular physiology, leading to synergy effects more than additive responses in an entire organism. Effort is now required to determine which interactions truly contribute to final physiological output. A receptor is the prime example of connectors among the networks. It functions, not simply as a signaling gateway, but also as an active trader by forming inter-receptor dimers. Furthermore, various receptors can modulate the function of the other receptors by input to common intracellular signaling pathways, establishing functional crosstalk among networks. Our findings by combined analyses of gene polymorphisms of two separate genes present evidences that such is the case with human body in a clinical setting: 1) an integrated effect of epidermal growth factor receptor (EGFR) and protease activated receptor-1 (PAR-1) on susceptibility to airway hyperresponsiveness (AHR), and 2) a crosstalk effect between muscarinic acetylcholine receptor (mAChRs) and β2 adrenoceptor (β2AR) on bronchodilatory response to anticholinergic agents in patients with COPD. These results indicate that these interactions are unlikely to be ‘noise’ but functionallyrelevant ‘crosstalk’ in a human body. This review attempts to highlight the clinically-relevant ‘crosstalk’ paradigm in a human body which provides us a novel insight necessary to investigate pathophysiology in common multifactorial diseases and to develop new drugs.
The Oxygen Therapy by A. Corsonello, C. Pedone, S. Scarlata, A. Zito, I. Laino, R. Antonelli-Incalzi (1103-1126).
Oxygen (O2) is a vital element. Shortage of O2 results in deranged metabolism and important changes in vascular tone with opposite effects on the systemic and pulmonary circulation. During hypoxemia, oxidative stress exposes the organism to a sort of accelerated senescence as well as to several acute untoward effects. Thus, hypoxemia should be promptly recognized and treated, hopefully by measures tailored to the pathophysiological mechanisms underlying hypoxemia. However, O2 therapy remains the most common therapy of hypoxemia, but it must be carefully tailored to relieve hypoxemia without provoking hyperoxia or hypercarbia. Then, the individual response to O2 as well as changing needs of O2 during sleep or exercise must be evaluated to provide the best O2 therapy. Hyperoxia, the effect of overcorrection of hypoxia, can dramatically impact the health status and threaten the survival of the newborn and, through different mechanisms and effects, the adult. A thorough knowledge of the pathophysiological bases of hypoxemia and O2 storage and delivery devices is then mandatory to administer O2 therapy guaranteeing for optimal correction of hypoxemia and minimizing the risk of hyperoxia. Consistent with this aim also is a careful scrutiny of instruments and procedures for monitoring the individual response to O2 over time. Thus, at variance from classical pharmacological therapy, performing O2 therapy requires a vast array of clinical and technical competences. The optimal integration of these competences is needed to optimize O2 therapy on individual bases.
The Impact of Oxidative Stress on Islet Transplantation and Monitoring the Graft Survival by Non-Invasive Imaging by K. M. Ramkumar, T. V. Sekar, E. Bhakkiyalakshmi, Kira Foygel, P. Rajaguru, F. Berger, R. Paulmurugan (1127-1146).
Islet transplantation is an attractive strategy to treat severe diabetic conditions in patients suffering from autoimmune derived diabetes, and it has currently been considered a forefront research arena in diabetes. Major aim of islet transplantation is to achieve successful insulin independent disease free survival. The key challenges in transplanted islets are the generation of reactive oxygen species (ROS) and associated oxidative stress, pro-inflammatory cytokine - (TNFα) mediated apoptotic induction, attack by immune cells, and achieving revascularization with minimal hypoxic microenvironment. Free radicals and their derivatives are constantly produced in living systems, but at relatively low level, and in a balanced state. Oxidative stress, which occurs as a result of an imbalance between the intracellular free radicals production and the cellular antioxidant defense mechanisms in the transplanted islets, can lead to cell death. The balance between oxidants and antioxidants in a cell can be easily disturbed by increase in ROS production or reduction in the level of cellular antioxidant defensive substances, which can cause many metabolic complications, including pancreatic β-cell damage. Antioxidants function as blockers of radical processes by eliminating harmful ROS produced during normal cellular metabolism. A complex antioxidant defense mechanism has been developed by nature in cells to protect the cellular homeostasis. This system mainly includes antioxidant enzymes, vitamins and minerals. As transplanted islet survival is crucial for achieving successful therapy, most of these antioxidants can be used as a supplement to scavenge the local ROS thereby improving the survival of transplanted islets. Currently, very few techniques have been routinely used to qualitatively and quantitatively assess the survival and function of islet grafts, especially to confirm the success of treatment, which includes metabolic parameters such as blood glucose, insulin and C-peptide levels. These biochemical measurements provide markers at only the late stages of islet rejection. Use of molecular imaging techniques has the potential for real-time non-invasive monitoring of the functional status and viability of transplanted islet grafts in living animals. This review mainly focuses on the current status of islet transplantations, potential preventive strategies used to reduce oxidative stress-mediated toxicity in islet grafts, and use of molecular imaging as a tool to quantitatively evaluate the functional status of the transplanted islets in living animals.
JAK Inhibitors: Pharmacology and Clinical Activity in Chronic Myeloprolipherative Neoplasms by J. Trelinski, T. Robak (1147-1161).
The Janus family kinases (JAKs), JAK1, JAK2, JAK3, and TYK2, are involved in cell growth, survival, development, and differentiation of a variety of cells, particularly immune cells and hematopoietic cells. They form a subgroup of the non-receptor protein tyrosine kinases. Activating mutations within each of the JAKs is associated with malignant transformations; the most common are mutations of JAK2 in polycythemia vera (PV) and other myeloproliferative neoplasms (MPN). Identification of the V617F mutation of the JAK2 gene (JAK2 V617F) led to an important breakthrough in the understanding of MPN disease pathogenesis. The JAK2 V617F mutation is present in the majority of PV patients, and about 50% of patients with essential thrombocythemia (ET) and primary myelofibrosis (PMF) are affected. This mutation leads to hyperactivation of JAK2, cytokine-independent signaling, and subsequent activation of downstream signaling networks. JAK2 ATP-competitive inhibitors that indirectly inhibit the JAK-STAT pathway are new candidates for the treatment of MPN. JAK2 inhibitors in development for the treatment of MPN have demonstrated clinical activity with minimal toxicity. These agents consistently alleviate constitutional symptoms and reduce spleen size in PMF and other MPN. However, some of these inhibitors have additional unique effects. Ruxolitinib causes a significant reduction in the level of pro-inflammatory cytokines. Another inhibitor, CYT387, improves anemia. Many other JAK2 inhibitors such as TG101348 or SAR302503, SB1518, CEP701 and LY2784544 are now under investigation for MPN development. In contrast tasocitinib, a predominantly JAK3 inhibitor, is being evaluated in a number of inflammatory and immunological diseases, including rheumatoid arthritis, psoriasis, ulcerative colitis, dry eye disease and in kidney transplant patients. In conclusion the use of JAK inhibitors in MPN and some of the immune-mediated disorders is a promising new strategy for therapy. However, definitive data from ongoing and future preclinical and clinical trials will aid in better defining the status of these drugs in the treatment of these diseases.
4-Mer Hyaluronan Oligosaccharides Stimulate Inflammation Response in Synovial Fibroblasts in Part via TAK-1 and in Part via p38-MAPK by G. M. Campo, A. Avenoso, A. D, ?, ?, Ascola, V. Prestipino, M. Scuruchi, G. Nastasi, A. Calatroni, S. Campo (1162-1172).
4-mer hyaluronan (HA) oligosaccharides stimulate pro-inflammatory effects in different cell types by interacting with both the toll-like receptor-4 (TLR-4) and -2 (TLR-2). This interaction induces the activation of the transforming growth factor activated kinase-1 (TAK-1) that activates the nuclear factor kappaB (NF-kB) either directly and/or through the activation of p38-mitogen-activated protein kinase (p38-MAPK). This in turn induces the transcription of proinflammatory mediators that prime inflammation. Our aim was to investigate the involvement of TAK-1 and p38-MAPK in 4-mer HA oligosaccharide-induced inflammatory response in mouse synovial fibroblasts obtained from normal DBA/J1 mice (NSF) and from mice subjected to collagen-induced arthritis (CIA). Treatment of NSF and rheumatoid arthritis synovial fibroblasts (RASF) with 4-mer HA showed a marked up-regulation of TLR-4, TLR-2, TAK-1 and p38-MAPK mRNA expression and of the related proteins, as well as NF-kB activation. High levels were also detected of TNF-α, IL- 1β, MMP-13 and iNOS. Treatment of NSF and RASF, previously stimulated with 4-mer HA oligosaccharides, with TAK- 1 and/or p38-MAPK specific inhibitors significantly reduced all the parameters, although the inhibitory effect of p38- MAPK was less effective than that of TAK-1. The addition of CD44 antibody to both NSF and RASF showed that CD44 was not involved in 4-mer HA-induced inflammation.
Synthesis and Biological Evaluation As Microtubule-Active Agents of Several Tetrahydrofuran and Spiroacetal Derivatives by M. Carda, J. Murga, J. Panos, C. A. Angulo-Pachon, J. Garcia-Pla, S. Diaz-Oltra, J. A. Marco, C. Trigili, M. Redondo-Horcajo, J. F. Diaz, I. Barasoain (1173-1182).
The stereoselective preparation of several molecules containing structural fragments of the tetrahydrofuran and spiroacetal type is described. Their degree of cytotoxicity and their interactions with tubulin have been investigated. It has been confirmed that the tetrahydrofuran derivatives are cytotoxic but, in contrast to previous reports, it has been found that the cytoxicity is not due to interactions with the microtubule network. Furthermore, and also in contrast to a previous report on closely related compounds, the spiroacetal derivatives do show interactions with tubulin, even though the precise mechanism and the binding site still remain to be established.
Design, SAR, Angiogenic Activities Evaluation and Pro-Angiogenic Mechanism of New Marine Cyclopeptide Analogs by J. Li, X. Lu, Q. Wu, G. Yu, Z. Xu, L. Qiu, Z. Pei, Y. Lin, J. Pang (1183-1194).
Angiogenesis plays an important role in a wide range of physiological processes. In this paper, we designed and synthesized a series of new analogs including 11 line-peptides and 9 cyclo-peptides by using a marine cyclopeptide (compound 21) which could stimulate angiogenesis on zebrafish in our previous studies as lead compound. The majority of compounds synthesized exhibited angiogenic effects when tested in vivo on zebrafish. Among them, compounds 3, 4, 10, and 15 exhibited much stronger angiogenic activities on zebrafish compared with the lead compound, and the line peptides 3 and 4 showed the most significant angiogenic activities. The SAR (structure-activity relationship) analysis revealed that Val, Lys and Ala are important for the activity. Further studies showed that 3 could concentration-dependently stimulate proliferation, migration and invasion in HUVECs (human umbilical vein endothelial cells) in vitro. To explore the angiogenesis mechanism of this series of compounds, a microarray analysis was carried out to study the gene expression profile and the result showed that 26 genes were upregulated more than 2 fold changes in treatment with 3 on zebrafish, in which mmp9 and mmp13a, two angiogenesis-related genes, increased up to 5-folds. Moreover, through the GO (gene ontology) enrichment analysis, mmp9 and mmp13a genes are the central nodes in the biological processes network. These results suggested that the pro-angiogenic mechanism of this kind of small molecular peptides is related with the expression and regulation of mmp genes in the signal transduction pathways. Additionally, one mmp inhibitor was chosen for further confirmation.
Luminol As In Situ Light Source in Meso-Tetraphenylporphyrin-Mediated Photodynamic Therapy by L. Huang, Ti-Chen Chen, Feng-Huei Lin (1195-1202).
The light sources used in current photodynamic therapy are mainly lasers or light emitting diodes, which are not suitable to treat large-volume tumors and those located in the inner body. To overcome the limitation, we propose an in situ light source to activate the photosensitizer and kill the cancer cells directly. In the present work, we use luminol as light source and meso-tetraphenylporphyrin as the photosensitizer. According to the results, cells incubated with meso-tetraphenylporphyrin, subsequently triggered by luminol, decreased significantly in assays including cell viability and cytotoxicity, while the other groups showed only minor differences. The flow cytometric and fluorescent microscopy analysis showed similar results as well. In the analysis of cell death pathway, cell shrinkage was noticed after photodynamic therapy treatment, which might refer to apoptosis. Briefly, we suggest that luminol is a promising light source in meso-tetraphenylporphyrin-mediated photodynamic therapy for its greater penetration depth and well matched emission wavelength.