Administration of a tropomyosin receptor kinase inhibitor attenuates sarcoma-induced nerve sprouting, neuroma formation and bone cancer pain

Pain often accompanies cancer and most current therapies for treating cancer pain have significant unwanted side effects. Targeting nerve growth factor (NGF) or its cognate receptor tropomyosin receptor kinase A (TrkA) has become an attractive target for attenuating chronic pain

Assembly of Protein Building Blocks Using a Short Synthetic Peptide

Combining proteins or their defined domains offers new enhanced functions. Conventionally, two proteins are either fused into a single polypeptide chain by recombinant means or chemically cross-linked. However, these strategies can have drawbacks such as poor expression (recombinant fusions) or aggregation and inactivation (chemical cross-linking), especially in the case of large multifunctional proteins. We developed a new linking method which allows site-oriented, noncovalent, yet irreversible stapling of modified proteins at neutral pH and ambient temperature. This method is based on two distinct polypeptide linkers which self-assemble in the presence of a specific peptide staple allowing on-demand and irreversible combination of protein domains. Here we show that linkers can either be expressed or be chemically conjugated to proteins of interest, depending on the source of the proteins. We also show that the peptide staple can be shortened to 24 amino acids still permitting an irreversible combination of functional proteins. The versatility of this modular technique is demonstrated by stapling a variety of proteins either in solution or to surfaces

Sensitization of spinal cord nociceptive neurons with a conjugate of substance P and cholera toxin

<p>Abstract</p> <p>Background</p> <p>Several investigators have coupled toxins to neuropeptides for the purpose of lesioning specific neurons in the central nervous system. By producing deficits in function these toxin conjugates have yielded valuable information about the role of these cells. In an effort to specifically stimulate cells rather than kill them we have conjugated the neuropeptide substance P to the catalytic subunit of cholera toxin (SP-CTA). This conjugate should be taken up selectively by neurokinin receptor expressing neurons resulting in enhanced adenylate cyclase activity and neuronal firing.</p> <p>Results</p> <p>The conjugate SP-CTA stimulates adenylate cyclase in cultured cells that are transfected with either the NK1 or NK2 receptor, but not the NK3 receptor. We further demonstrate that intrathecal injection of SP-CTA in rats induces the phosphorylation of the transcription factor cyclic AMP response element binding protein (CREB) and also enhances the expression of the immediate early gene c-Fos. Behaviorally, low doses of SP-CTA (1 μg) injected intrathecally produce thermal hyperalgesia. At higher doses (10 μg) peripheral sensitivity is suppressed suggesting that descending inhibitory pathways may be activated by the SP-CTA induced sensitization of spinal cord neurons.</p> <p>Conclusion</p> <p>The finding that stimulation of adenylate cyclase in neurokinin receptor expressing neurons in the spinal cord produces thermal hyperalgesia is consistent with the known actions of these neurons. These data demonstrate that cholera toxin can be targeted to specific cell types by coupling the catalytic subunit to a peptide agonist for a g-protein coupled receptor. Furthermore, these results demonstrate that SP-CTA can be used as a tool to study sensitization of central neurons in vivo in the absence of an injury.</p

Increased neurogenesis and brain-derived neurotrophic factor in neurokinin-1 receptor gene knockout mice

It has previously been shown that chronic treatment with antidepressant drugs increases neurogenesis and levels of brain-derived neurotrophic factor in the hippocampus. These changes have been correlated with changes in learning and long-term potentiation and may contribute to the therapeutic efficacy of antidepressant drug treatment. Recently, antagonists at the neurokinin-1 receptor, the preferred receptor for the neuropeptide substance P, have been shown to have antidepressant activity. Mice with disruption of the neurokinin-1 receptor gene are remarkably similar both behaviourally and neurochemically to mice maintained chronically on antidepressant drugs. We demonstrate here that there is a significant elevation of neurogenesis but not cell survival in the hippocampus of neurokinin-1 receptor knockout mice. Neurogenesis can be increased in wild-type but not neurokinin-1 receptor knockout mice by chronic treatment with antidepressant drugs which preferentially target noradrenergic and serotonergic pathways. Hippocampal levels of brain-derived neurotrophic factor are also two-fold higher in neurokinin-1 receptor knockout mice, whereas cortical levels are similar. Finally, we examined hippocampus-dependent learning and memory but found no clear enhancement in neurokinin-1 receptor knockout mice. These data argue against a simple correlation between increased levels of neurogenesis or brain-derived neurotrophic factor and mnemonic processes in the absence of increased cell survival. They support the hypothesis that increased neurogenesis, perhaps accompanied by higher levels of brain-derived neurotrophic factor, may contribute to the efficacy of antidepressant drug therapy.This research was supported by the Wellcome Trust, a European Community Marie Curie fellowship to S.M. and a Boehringer Ingelheim Fonds Predoctoral Fellowship to M.P. C.A.G. is on the Wellcome Trust Four-year PhD in Neuroscience at UCL.Peer reviewe

Simultaneous reduction in cancer pain, bone destruction, and tumor growth by selective inhibition of cyclooxygenase-2

More than half of all chronic cancer pain arises from metastases to bone, and bone cancer pain is one of the most difficult of all persistent pain states to fully control. Several tumor types including sarcomas and breast, prostate, and lung carcinomas grow in or preferentially metastasize to the skeleton where they proliferate, and induce significant bone remodeling, bone destruction, and cancer pain. Many of these tumors express the isoenzyme cycloxygenase-2 (COX-2), which is involved in the synthesis of prostaglandins. To begin to define the role COX-2 plays in driving bone cancer pain, we used an in vivo model where murine osteolytic 2472 sarcoma cells were injected and confined to the intramedullary space of the femur in male C3HHeJ mice. After tumor implantation, mice develop ongoing and movement-evoked bone cancer pain-related behaviors, extensive tumor-induced bone resorption, infiltration of the marrow space by tumor cells, and stereotypic neurochemical alterations in the spinal cord reflective of a persistent pain state. Thus, after injection of tumor cells, bone destruction is first evident at day 6, and pain-related behaviors are maximal at day 14. A selective COX-2 inhibitor was administered either acutely [NS398; 100 mg/kg, i.p.] on day 14 or chronically in chow {MF. tricyclic; 0.015%, p.o.} from day 6 to day 14 after tumor implantation. Acute administration of a selective COX-2 inhibitor attenuated both ongoing and movement-evoked bone cancer pain, whereas chronic inhibition of COX-2 significantly reduced ongoing and movement-evoked pain behaviors, and reduced tumor burden, osteoclastogenesis, and bone destruction by >50%. The present results suggest that chronic administration of a COX-2 inhibitor blocks prostaglandin synthesis at multiple sites, and may have significant clinical utility in the management of bone cancer and bone cancer pain.Supported by NIH Grants from the National Institute of Neurologic Disorders and Stoke (NS23970), the National Institute for Drug Abuse (DA11986), National Institute of Dental and Craniofacial Research Dentist Scientist Award (DSA) DE00270, Training Grant DE07288, and a Merit Review from the Veterans Administration.Peer reviewe

A computational procedure for functional characterization of potential marker genes from molecular data: Alzheimer's as a case study

Abstract Background A molecular characterization of Alzheimer's Disease (AD) is the key to the identification of altered gene sets that lead to AD progression. We rely on the assumption that candidate marker genes for a given disease belong to specific pathogenic pathways, and we aim at unveiling those pathways stable across tissues, treatments and measurement systems. In this context, we analyzed three heterogeneous datasets, two microarray gene expression sets and one protein abundance set, applying a recently proposed feature selection method based on regularization. Results For each dataset we identified a signature that was successively evaluated both from the computational and functional characterization viewpoints, estimating the classification error and retrieving the most relevant biological knowledge from different repositories. Each signature includes genes already known to be related to AD and genes that are likely to be involved in the pathogenesis or in the disease progression. The integrated analysis revealed a meaningful overlap at the functional level. Conclusions The identification of three gene signatures showing a relevant overlap of pathways and ontologies, increases the likelihood of finding potential marker genes for AD.</p

Presynaptically Localized Cyclic GMP-Dependent Protein Kinase 1 Is a Key Determinant of Spinal Synaptic Potentiation and Pain Hypersensitivity

Electrophysiological and behavioral experiments in mice reveal that a cGMP-dependent kinase amplifies neurotransmitter release from peripheral pain sensors, potentiates spinal synapses, and leads to exaggerated pain

In pursuit of P2X3 antagonists: novel therapeutics for chronic pain and afferent sensitization

Treating pain by inhibiting ATP activation of P2X3-containing receptors heralds an exciting new approach to pain management, and Afferent's program marks the vanguard in a new class of drugs poised to explore this approach to meet the significant unmet needs in pain management. P2X3 receptor subunits are expressed predominately and selectively in so-called C- and Aδ-fiber primary afferent neurons in most tissues and organ systems, including skin, joints, and hollow organs, suggesting a high degree of specificity to the pain sensing system in the human body. P2X3 antagonists block the activation of these fibers by ATP and stand to offer an alternative approach to the management of pain and discomfort. In addition, P2X3 is expressed pre-synaptically at central terminals of C-fiber afferent neurons, where ATP further sensitizes transmission of painful signals. As a result of the selectivity of the expression of P2X3, there is a lower likelihood of adverse effects in the brain, gastrointestinal, or cardiovascular tissues, effects which remain limiting factors for many existing pain therapeutics. In the periphery, ATP (the factor that triggers P2X3 receptor activation) can be released from various cells as a result of tissue inflammation, injury or stress, as well as visceral organ distension, and stimulate these local nociceptors. The P2X3 receptor rationale has aroused a formidable level of investigation producing many reports that clarify the potential role of ATP as a pain mediator, in chronic sensitized states in particular, and has piqued the interest of pharmaceutical companies. P2X receptor-mediated afferent activation has been implicated in inflammatory, visceral, and neuropathic pain states, as well as in airways hyperreactivity, migraine, itch, and cancer pain. It is well appreciated that oftentimes new mechanisms translate poorly from models into clinical efficacy and effectiveness; however, the breadth of activity seen from P2X3 inhibition in models offers a realistic chance that this novel mechanism to inhibit afferent nerve sensitization may find its place in the sun and bring some merciful relief to the torment of persistent discomfort and pain. The development philosophy at Afferent is to conduct proof of concept patient studies and best identify target patient groups that may benefit from this new intervention

Contemporary Management of Locally Advanced and Recurrent Rectal Cancer: Views from the PelvEx Collaborative

Pelvic exenteration is a complex operation performed for locally advanced and recurrent pelvic cancers. The goal of surgery is to achieve clear margins, therefore identifying adjacent or involved organs, bone, muscle, nerves and/or vascular structures that may need resection. While these extensive resections are potentially curative, they can be associated with substantial morbidity. Recently, there has been a move to centralize care to specialized units, as this facilitates better multi-disciplinary care input. Advancements in pelvic oncology and surgical innovation have redefined the boundaries of pelvic exenterative surgery. Combined with improved neoadjuvant therapies, advances in diagnostics, and better reconstructive techniques have provided quicker recovery and better quality of life outcomes, with improved survival This article provides highlights of the current management of advanced pelvic cancers in terms of surgical strategy and potential future developments

Identification of neural networks that contribute to motion sickness through principal components analysis of fos labeling induced by galvanic vestibular stimulation

Motion sickness is a complex condition that includes both overt signs (e.g., vomiting) and more covert symptoms (e.g., anxiety and foreboding). The neural pathways that mediate these signs and symptoms are yet to identified. This study mapped the distribution of c-fos protein (Fos)-like immunoreactivity elicited during a galvanic vestibular stimulation paradigm that is known to induce motion sickness in felines. A principal components analysis was used to identify networks of neurons activated during this stimulus paradigm from functional correlations between Fos labeling in different nuclei. This analysis identified five principal components (neural networks) that accounted for greater than 95% of the variance in Fos labeling. Two of the components were correlated with the severity of motion sickness symptoms, and likely participated in generating the overt signs of the condition. One of these networks included neurons in locus coeruleus, medial, inferior and lateral vestibular nuclei, lateral nucleus tractus solitarius, medial parabrachial nucleus and periaqueductal gray. The second included neurons in the superior vestibular nucleus, precerebellar nuclei, periaqueductal gray, and parabrachial nuclei, with weaker associations of raphe nuclei. Three additional components (networks) were also identified that were not correlated with the severity of motion sickness symptoms. These networks likely mediated the covert aspects of motion sickness, such as affective components. The identification of five statistically independent component networks associated with the development of motion sickness provides an opportunity to consider, in network activation dimensions, the complex progression of signs and symptoms that are precipitated in provocative environments. Similar methodology can be used to parse the neural networks that mediate other complex responses to environmental stimuli. © 2014 Balaban et al