In vivo neurotrophic effects of GDNF on neonatal and adult facial motor neurons

Motor neurons require neurotrophic factor(s) for their survival during development and for maintenance of function in adulthood. In vivo studies have shown that motor neurons respond to a variety of molecules, including ciliary neurotrophic factor, members of the neurotrophin family, and the insulin growth factor IGF-1 (refs 3-13). Here we investigate the potential motor neuron neurotrophic effects of glial-cell-line-derived neurotrophic factor (GDNF), initially identified as a neurotrophic factor for substantia nigra dopaminergic neurons. We find that GDNF is retrogradely transported, in a receptor-mediated fashion, by spinal cord motor neurons in neonatal rats. Local application of GDNF to the transected facial nerve prevents the massive motor neuron cell death and atrophy that normally follows axotomy in the neonatal period. In adult rats, GDNF administered locally or systemically can markedly attenuate the lesion-induced decrease of choline acetyltransferase immunoreactivity in the facial nucleus. Our data indicate that GDNF has very profound neurotrophic effects in vivo on developing as well as on adult motor neurons, and is the most potent motor neuron trophic factor found so far.

Strategies and Approaches of Targeting STAT3 for Cancer Treatment

Signal transducer and activator of transcription 3 (STAT3) is a transcription factor that regulates the expression of genes related to cell cycle, cell survival, and immune response associated with cancer progression and malignancy in a number of cancer types. Once activated, STAT3 forms a homodimer and translocates to the nucleus where it binds DNA promoting the translation of target genes associated with antiapoptosis, angiogenesis, and invasion/migration. In normal cells, levels of activated STAT3 remain transient; however, STAT3 remains constitutively active in approximately 70% of human solid tumors. The pivotal role of STAT3 in tumor progression has promoted a campaign in drug discovery to identify small molecules that disrupt the function of STAT3. A range of approaches have been used to identify novel small molecule inhibitors of STAT3, including high-throughput screening of chemical libraries, computational-based virtual screening, and fragment-based design strategies. The most common approaches in targeting STAT3 activity are either via the inhibition of tyrosine kinases capable of phosphorylating and thereby activating STAT3 or by preventing the formation of functional STAT3 dimers through disruption of the SH2 domains. However, the targeting of the STAT3 DNA-binding domain and disruption of binding of STAT3 to its DNA promoter have not been thoroughly examined, mainly due to the lack of adequate assay systems. This review summarizes the development of STAT3 inhibitors organized by the approach used to inhibit STAT3, the current inhibitors of each class, and the assay systems used to evaluate STAT3 inhibition and offers an insight into future approaches for small molecule STAT3 inhibitor development.

Distribution of intracerebral ventricularly administered neurotrophins in rat brain and its correlation with trk receptor expression

To assess the potential effectiveness by which injected neurotrophins can diffuse throughout the brain, we used autoradiographic and immunohistochemical techniques to examine the brain distributions of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3) after a single injection into the lateral cerebral ventricle (ICV) in rats. As described previously, ICV-injected NGF labeled cholinergic neurons in the basal forebrain. Injection of BDNF resulted in few or no labeled neurons in the basal forebrain or in the substantia nigra. However, very intense labeling was associated with the ventricular walls and immediate parenchyma. The distribution of NT-3 after ICV injection was intermediate between that of NGF and BDNF. In the basal forebrain, similar neurotrophin distributions were observed in neonate versus adult animals. Our in situ hybridization analysis has shown that mRNA encoding the BDNF receptor(s) (trkB) is highly expressed by ependymal cells as well as by many neurons and glia. On the other hand, expression of the high-affinity NGF receptor (trkA) is restricted to cholinergic neurons in basal forebrain and striatum. In addition, staining with antisera specific for the trkA or trkB receptors demonstrated that their expression patterns closely reflect their mRNA distributions. Taken together, these data suggest that the presence of the trkB receptor on the ependymal layer of the ventricle and its expression throughout the brain parenchyma represents a significant impediment to the adequate diffusion of ICV-injected BDNF into the brain for delivery to target neurons.

Influences of neurotrophins on mammalian motoneurons in vivo

Several recently reported investigations have shown that a member of the neurotrophin family of neuronal growth factors, brain-derived neurotrophic factor (BDNF), supports motoneurons in vitro and rescues motoneurons from naturally occurring and axotomy-induced cell death (Oppenheim et al., 1992b; Sendtner et al., 1992b; Yan et al., 1992; Koliatsos et al., 1993; Henderson et al., 1993). In the current study, we have explored the issue of whether BDNF and other neurotrophins act to regulate motoneuron survival during development and asked whether synthesis of motoneuron transmitter enzymes is also regulated. We first examined whether spinal motoneurons in newborn animals could retrogradely transport iodinated neurotrophins from their targets in a specific, receptor-mediated manner. We found that motoneurons readily transported NGF, BDNF, and neurotrophin-3 (NT-3). The retrograde transport of one factor could be completely or largely blocked by excess of unlabeled homologous factor, but only partially blocked by excess of unlabeled heterologous factors. Since previous studies have shown that these three neurotrophins bind to the low-affinity NGF receptor, p75NGFR, with similar affinity, our data suggest that the retrograde transport of neurotrophins by motoneurons may be mediated by additional components, such as the trk family of proto-oncogenes. Consistent with this hypothesis, we demonstrate here that motoneurons express mRNA for two members of the trk family, trkB and trkC. Furthermore, both trkB and trkC were expressed by E13, consistent with a role for BDNF and NT-3 in regulating important developmental events involving motoneurons such as naturally occurring cell death. In order to determine which members of the neurotrophin family influence motoneuron survival and to assess the generality of their effects, we evaluated the abilities of NGF, BDNF, and NT-3 to save both spinal and cranial motoneurons after neonatal axotomy. Locally applied BDNF saved 40-70% of motoneurons which would ordinarily die after axotomy in lumbar and cranial motor pools, depending on the treatment protocol employed. NT-3 also exhibited some ability to rescue motoneurons and saved 20-25% of motoneurons which would die in the absence of treatment. Finally, we asked whether neurotrophins could influence synthesis of transmitter enzymes by motoneurons as well as their survival after axotomy. Locally applied BDNF and NT-3 could partially prevent the decrease of protein contents in L4 and L5 ventral roots which normally follows sciatic nerve transection. However, treatment with these neurotrophins did not prevent the decrease in choline acetyltransferase (ChAT) activity in L4 and L5 ventral roots which results from this procedure.(ABSTRACT TRUNCATED AT 400 WORDS)

The Caenorhabditis elegans unc-60 gene encodes proteins homologous to a family of actin-binding proteins

Mutations in the unc-60 gene of the nematode Caenorhabditis elegans result in paralysis. The thin filaments of the muscle cells are severely disorganized and not bundled with myosin into functional contractile units. Here we report the cloning and sequence of unc-60. Two unc-60 transcripts, 1.3 and 0.7 kb in size, were detected. The transcripts share a single exon encoding only the initial methionine, yet encode proteins with homologous sequences. The predicted protein products are 165 and 152 amino acids in length and their sequences are 38% identical. Both proteins are homologous to a family of actin depolymerizing proteins identified in vertebrate, plant and protozoan systems. We propose that the unc-60 locus encodes proteins that depolymerize growing actin filaments in muscle cells, and that these proteins are required for the assembly of actin filaments into the contractile myofilament lattice of C. elegans muscle. unc-60 has an essential function in development, since one unc-60 allele, s1586, has a recessive lethal phenotype. Our characterization of s1586 has shown that it is a small deletion which disrupts both coding regions.

Cyclin-Dependent Kinase (CDK) Inhibitors: Structure-Activity Relationships and Insights into the CDK-2 Selectivity of 6-Substituted 2-Arylaminopurines

Purines and related heterocycles substituted at C-2 with 4'-sulfamoylanilino and at C-6 with a variety of groups have been synthesized with the aim of achieving selectivity of binding to CDK2 over CDK1. 6-Substituents that favor competitive inhibition at the ATP binding site of CDK2 were identified and typically exhibited 10-80-fold greater inhibition of CDK2 compared to CDK1. Most impressive was 4-((6-([1,1'-biphenyl]-3-yl)-9H-purin-2-yl)amino) benzenesulfonamide (73) that exhibited high potency toward CDK2 (IC50 0.044 μM) but was ∼2000-fold less active toward CDK1 (IC50 86 μM). This compound is therefore a useful tool for studies of cell cycle regulation. Crystal structures of inhibitor-kinase complexes showed that the inhibitor stabilizes a glycine-rich loop conformation that shapes the ATP ribose binding pocket and that is preferred in CDK2 but has not been observed in CDK1. This aspect of the active site may be exploited for the design of inhibitors that distinguish between CDK1 and CDK2.

How well prepared are medical students for their first year as doctors? The views of consultants and specialist registrars in two teaching hospitals

OBJECTIVE

To evaluate (1) the extent to which first year doctors (foundation year 1 doctors, F1s) in two teaching hospitals in the Trent Deanery were rated by specialist registrars (SpRs) and consultants as being well prepared for practice; (2) the importance ascribed by SpRs and consultants to the various items of core knowledge, skills and attitudes outlined in the publication of the General Medical Council, Tomorrow's Doctors.

METHOD

SpRs and consultants were asked to rate: how well prepared F1s were in a range of items of core knowledge, skills and attitudes that a new medical graduate must possess as outlined in Tomorrow's Doctors; the importance for a new doctor of each item of core knowledge, skills and attitudes; and how well the medical school had prepared F1s in respect of key generic issues related to their practice.

RESULTS

In most of the items of core knowledge, skills and attitudes covering 8 of the 11 topic areas of Tomorrow's Doctors, F1s were seen as not prepared for starting work, especially in regard to clinical and practical skills and the more challenging communication skills. They were best prepared in asking for help and in basic communication skills.

CONCLUSIONS

Overall, F1s in the study were not well prepared either to perform the tasks that await them or in terms of most of the specific background knowledge and skills necessary for the successful execution of those tasks. The level of preparedness raises important issues about medical training and transition from medical graduate to first year doctor. Further research is needed to determine whether this situation exists in other regions of the UK.

Attitudinal factors associated with community pharmacists' involvement in services for drug misusers

AIM

To assess the relationship between pharmacists' attitudes towards drug misusers and the availability and provision of services for drug misusers.

DESIGN

A cross-sectional postal questionnaire survey.

SETTING

All community pharmacies in Scotland (n = 1142).

PARTICIPANTS

A total of 864 pharmacists managing community pharmacies on a day-to-day basis (response rate 79%).

MEASUREMENTS

Descriptive data were collected on demography, drug misuse services provided and training in drug misuse. Attitude statements were used to measure attitudes to drug misusers, the role of the pharmacist in dispensing controlled drugs and providing injecting equipment, providing advice on drug misuse and financial aspects of service provision. Statements were incorporated into a scale which was correlated with behavioural data on whether and how services were provided.

RESULTS

The attitude scale had good internal reliability and was unidimensional. Pharmacists that provided needle/syringe exchanges, sold needles/syringes, dispensed methadone, supervised the consumption of methadone and provided health promotion services to drug misusers had significantly more positive attitudes towards drug misusers. Attitudes were associated with health board area, sex and number of years registered as a pharmacist. After controlling for these characteristics, attitude was an independent predictor of whether needles/syringes were sold, methadone was dispensed and methadone consumption supervised.

CONCLUSIONS

Addressing negative attitudes could encourage more pharmacists to provide services and enhance the process of service delivery.

Allosteric inhibitors of the Eya2 phosphatase are selective and inhibit Eya2-mediated cell migration

Eya proteins are essential co-activators of the Six family of transcription factors and contain a unique tyrosine phosphatase domain belonging to the haloacid dehalogenase family of phosphatases. The phosphatase activity of Eya is important for the transcription of a subset of Six1-target genes, and also directs cells to the repair rather than apoptosis pathway upon DNA damage. Furthermore, Eya phosphatase activity has been shown to mediate transformation, invasion, migration, and metastasis of breast cancer cells, making it a potential new drug target for breast cancer. We have previously identified a class of N-arylidenebenzohydrazide compounds that specifically inhibit the Eya2 phosphatase. Herein, we demonstrate that these compounds are reversible inhibitors that selectively inhibit the phosphatase activity of Eya2, but not Eya3. Our mutagenesis results suggest that this class of compounds does not bind to the active site and the binding does not require the coordination with Mg(2+). Moreover, these compounds likely bind within a site on the opposite face of the active site, and function as allosteric inhibitors. We also demonstrate that this class of compounds inhibits Eya2 phosphatase-mediated cell migration, setting the foundation for these molecules to be developed into chemical probes for understanding the specific function of the Eya2 phosphatase and to serve as a prototype for the development of Eya2 phosphatase specific anti-cancer drugs.

Selective Targeting of RSK Isoforms in Cancer

The p90 ribosomal S6 kinase family (RSK1-4) is a group of highly conserved Ser/Thr kinases that act as downstream effectors of the Ras/Raf/MEK/ERK signaling pathway. The RSKs phosphorylate a range of substrates involved in transcription, translation, cell cycle regulation, and cell survival. Although the RSKs have a high degree of sequence homology, their functional differences in cancer are of great interest. Current RSK inhibitors target more than one RSK isoform, and this may limit their efficacy as anticancer agents. Here, we review the structure and function of the RSK kinases, their role in cancer growth and survival, and their potential as modulators of chemoresistance. In addition, we summarize the development of current RSK inhibitors and their limitations.

Community pharmacy services for drug misusers in Scotland: what difference does 5 years make?

AIMS

To assess current levels of participation of community pharmacists in needle exchange provision, assess participation in dispensing any drugs for drug misuse, explore methadone dispensing practice, assess involvement in health promotion for drug misusers, assess levels of training in drug misuse and compare all of the above with data from 5 years previously.

DESIGN

A cross-sectional postal questionnaire.

SETTING

All community pharmacies in Scotland (n = 1162).

PARTICIPANTS

A total of 969 pharmacists managing community pharmacies on a day-to-day basis (response rate 83.4%).

MEASUREMENTS

Descriptive data were collected on demography, drug misuse services provided and training. Data were combined with a dataset from an identical survey conducted 5 years previously for statistical comparison.

RESULTS

Levels of needle exchange provision has not changed significantly (9.7% in 2000 compared to 8.6% in 1995). Of all respondents, 71.5% now dispense drug for the management of drug misuse, 68.9% dispense methadone and 56.7% provide a supervised methadone consumption service. The number of methadone clients receiving methadone through pharmacies has increased from 3387 in 1995 to 8792 in 2000 and the mean number of clients dispensed methadone per pharmacy has increased from 7.3 in 1995 to 13.2 in 2000; 65.1% of all methadone clients now consume their methadone under pharmacist supervision. The proportion of pharmacists dispensing methadone who provide a supervised consumption service has increased significantly from 37% to 82.8%. Considerable changes in pharmacy practice are evident with significant increases in the number of pharmacists who always lay down ground rules, ask for identification on first visits, make up prescriptions in advance and provide verbal advice and leaflets on the management of drug misuse. Training in drug misuse doubled from 31.8% to 66.8%.

CONCLUSIONS

Community pharmacy involvement with drug misusers has increased dramatically in the last 5 years. However, this increase is largely in methadone dispensing and supervision. Pharmacists appear to be more proactive in providing advice and information, perhaps as a result of greater training.

A WEE1 Inhibitor Analog of AZD1775 Maintains Synergy with Cisplatin and Demonstrates Reduced Single-Agent Cytotoxicity in Medulloblastoma Cells

The current treatment for medulloblastoma includes surgical resection, radiation, and cytotoxic chemotherapy. Although this approach has improved survival rates, the high doses of chemotherapy required for clinical efficacy often result in lasting neurocognitive defects and other adverse events. Therefore, the development of chemosensitizing agents that allow dose reductions of cytotoxic agents, limiting their adverse effects but maintaining their clinical efficacy, would be an attractive approach to treat medulloblastoma. We previously identified WEE1 kinase as a new molecular target for medulloblastoma from an integrated genomic analysis of gene expression and a kinome-wide siRNA screen of medulloblastoma cells and tissue. In addition, we demonstrated that WEE1 prevents DNA damage-induced cell death by cisplatin and that the WEE1 inhibitor AZD1775 displays synergistic activity with cisplatin. AZD1775 was developed as a WEE1 inhibitor from an initial hit from a high-throughput screen. However, given the lack of structure-activity data for AZD1775, we developed a small series of analogs to determine the requirements for WEE1 inhibition and further examine the effects of WEE1 inhibition in medulloblastoma. Interestingly, the compounds that inhibited WEE1 in the same nanomolar range as AZD1775 had significantly reduced single-agent cytotoxicity compared with AZD1775 and displayed synergistic activity with cisplatin in medulloblastoma cells. The potent cytotoxicity of AZD1775, unrelated to WEE1 inhibition, may result in dose-limiting toxicities and exacerbate adverse effects; therefore, WEE1 inhibitors that demonstrate low cytotoxicity could be dosed at higher concentrations to chemosensitize the tumor and potentiate the effect of DNA-damaging agents such as cisplatin.

The health of fishermen in the catching sector of the fishing industry: a gap analysis

Offshore fishing is a sizeable industry in the UK and it is one of the most dangerous occupations. Long hours, extreme weather and working with heavy machinery contribute to a high mortality rate in fishermen. Despite a long-standing acknowledgement of the dangers and high mortality associated with fishing, there has been little research in this field. Although there have been developments within the industry in terms of safety, there has been little emphasis on the relationship between health, the environment and performance at work. This paper reviews the international literature on the health of fishermen, and describes the main findings and highlights gaps in current evidence. Areas for further research that would inform the future development of an evidence-based occupational health service for the offshore fishing industry are discussed.

Public opinion of drug treatment policy: exploring the public's attitudes, knowledge, experience and willingness to pay for drug treatment strategies

BACKGROUND

Research evidence is strong for opiate replacement treatment (ORT). However, public opinion (attitudes) can be at odds with evidence. This study explored the relationships between, attitudes, knowledge of drugs and a range of socio-demographic variables that potentially influence attitude. This is relevant in the current policy arena in which a major shift from harm reduction to, rehabilitation is underway.

METHODS

A cross sectional postal questionnaire survey in Scotland was conducted where the drug, treatment strategy has changed from harm-reduction to recovery-based. A random sample (N=3000), of the general public, >18 years, and on the electoral register was used. The questionnaire was largely structured with tick box format but included two open questions for qualitative responses. Valuation was measured using the economic willingness-to-pay (WTP) method.

RESULTS

The response rate was 38.1% (1067/2803). Less than 10% had personal experience of drug, misuse but 16.7% had experience of drug misuse via a friend/acquaintance. Regression modelling revealed more positive attitudes towards drug users in those with personal experience of drug misuse, (p<0.001), better knowledge of drugs (p=0.001) and higher income (those earning >£50,000 per, annum compared to <£15K; p=0.01). Over half of respondents were not willing to pay anything for drug treatment indicating they did not value these treatments at all. Respondents were willing-to-pay most for community rehabilitation and least for methadone maintenance treatment. Qualitative analysis of open responses indicated many strong negative attitudes, doubts over the efficacy of methadone and consideration of addiction as self-inflicted. There was ambivalence with respondents weighing up negative feelings towards treatment against societal benefit.

CONCLUSIONS

There is a gap between public attitudes and evidence regarding drug treatment. Findings suggest a way forward might be to develop and evaluate treatment that integrates ORT with a community rehabilitative approach. Evaluation of public engagement/education to improve knowledge of drug treatment effectiveness is recommended.

General practice management of illicit drug users in Scotland: a national survey

AIMS

To describe the level of involvement of general practitioners (GPs) in the management of illicit drug dependency; nature of current practice in the management of illicit drug dependency; influence of guidelines on practice; GP training experience and needs; and to consider the policy implications of the findings.

DESIGN

A cross-sectional postal questionnaire survey.

SETTING

General practice in Scotland.

PARTICIPANTS

A 1 : 4 randomized sample (n = 926) of general practice principals, stratified according to age, gender and number of practice partners.

MEASUREMENTS

A structured postal questionnaire.

FINDINGS

A 63% response rate was achieved after two reminders (n = 583). Sixty per cent of respondents treated drug users, 51.5% provided methadone maintenance but only 58% used doses in the recommended range. Maintenance prescribing of dihydrocodeine and benzodiazepines was provided by 24% and 44.8% of respondents, respectively. While 79.3% had received the national clinical guidelines only 22.5% believed this had influenced their practice. Only a third of respondents had received drug dependency training. Beliefs about whether prescribing for drug misusers is part of a GPs professional remit was split.

CONCLUSIONS

There was relatively high involvement with drug users, with methadone maintenance being the most common treatment provided. Maintenance prescribing of dihydrocodeine and benzodiazepines were common despite a lack of clinical evidence supporting the effectiveness of these treatments. This may reflect the nature of the presenting drug problems and highlights the difficulties some GPs may face in managing multiple drug dependencies within current guidelines. Further local training to implement guidelines along with trials of alternative treatments currently outwith guidelines should be considered.

The health and lifestyle of Scottish fishermen: a need for health promotion

It has long been known that fishing is one of the most dangerous occupations. In the year 2001, 33 boats were lost and 10 fishermen killed in UK waters. Despite the dangerous nature of the occupation, very little research has been conducted on fishermen's health and safety. The few studies that have been conducted are spread widely around the globe, and tend to focus on mortality rates and accidents. Few studies considered fishermen's lifestyle behaviours. To address this gap in current knowledge research was conducted to gain an understanding of health and lifestyle issues affecting Scottish fishermen. Data was collected using a postal questionnaire survey in the Scottish fishing population and health diaries in a small subsample. High rates of smoking were prevalent and passive smoking was a considerable problem. Fewer fishermen drank alcohol compared to the general population, but fishermen lacked knowledge about what safe levels of alcohol consumption were. Diet was lacking in fruit and vegetables, and meals were eaten at very erratic intervals. Fishermen may benefit from health promotion and education in the areas of smoking, diet and alcohol consumption.

Prescribing and dispensing for drug misusers in primary care: current practice in Scotland

BACKGROUND

Substitute prescribing has increased in Scotland, as in the rest of the UK. Both GPs and pharmacists are becoming increasingly involved in service provision for drug misusers, but anecdotal evidence has suggested considerable variation in prescribing and dispensing practice.

OBJECTIVE

We aimed to gain baseline data on (i) current prescribing practice by medical practitioners and drug agencies, (ii) dispensing practice by community pharmacists across Scotland for the management of drug misuse and (iii) variations in practice between health boards.

METHODS

A structured questionnaire was posted to all community pharmacies in Scotland (n = 1142), in order to gather information on prescribing from prescriptions held at the time of the survey and information on current dispensing practice in managing drug misusers.

RESULTS

The response rate was 79%. Sixty-one per cent of pharmacists were currently dispensing drugs for the management of drug misuse. The most frequently prescribed drug was methadone, dispensed by 46% of pharmacists, followed by diazepam (37%), dihydrocodeine (26%) and temazepam (25%). Sixty-five per cent of methadone prescriptions were dispensed daily on request from the prescriber. Of the 3387 people receiving a methadone prescription, 32.9% had to consume their daily dose on the pharmacy premises under a pharmacist's supervision. Nineteen per cent of pharmacies currently provided a service to supervise the consumption of methadone by clients and a further 14% were prepared to but had no current demand. The proportion of prescriptions requiring supervision of methadone consumption varied considerably between health board areas.

CONCLUSIONS

Methadone is the most widely prescribed drug for drug misuse across Scotland, but there is considerable variation between health board areas in how prescribing is managed. Prescribing practice should be revised locally, in a process involving GPs and pharmacists. Pharmacists have an important role in preventing drug misuse in primary care, but need further support to optimize good practice.

Molecular docking of substituted pteridinones and pyrimidines to the ATP-binding site of the N-terminal domain of RSK2 and associated MM/GBSA and molecular field datasets

The data have been obtained for a series of substituted pteridinones and pyrimidines that were developed based on BI-D1870 to establish a structure-activity relationship for RSK inhibition. The 19 compounds, 12 of these with R- and S-isomeric forms, were docked into the ATP-binding site of the N-terminal domain of the RSK2 kinase using Schrodinger Glide. The binding conformations of these molecules and their interactions with RSK2 may inform the development of further small molecule RSK inhibitors. The molecular mechanics energies combined with the generalized Born and surface area continuum solvation (MM-BGSA) method was used to estimate the free energy of binding of the small molecules with RSK2. The molecular field characteristics of the docked confirmations of the inhibitors was examined using Cresset Forge software. The synthesis and evaluation of these compounds was reported in the related research article: Substituted pteridinones as p90 ribosomal S6 protein kinase 2 (RSK2) inhibitors: a structure-activity study (Casalvieri et al., 2020).

Combined treatment of acute EAE in Lewis rats with TNF-binding protein and interleukin-1 receptor antagonist

Experimental autoimmune encephalomyelitis (EAE) is a term given to describe a collection of animal models representing the human disease multiple sclerosis (MS). Although not fully understood, the involvement of cytokines and the immune system in either EAE or human MS is well established. Past efforts have shown that inhibition of proinflammatory cytokines tumor necrosis factor (TNF-alpha) or interleukin-1 (IL-1) result in amelioration of acute EAE in Lewis rats. The present study examined this model for the effect of concomitant inhibition of both TNF-alpha and IL-1, which resulted in a modest but significant therapeutic effect that was superior to inhibition of either single agent alone with respect to four of the five variables used to follow the progression of disease in this model, i.e., clinical severity, frequency of disease, loss of body weight, and day of onset. These results are in accordance with the idea that combination treatments are likely to prove superior to single agent therapy in the treatment of autoimmune inflammatory disease.

Structure-Based Screen Identification of a Mammalian Ste20-like Kinase 4 (MST4) Inhibitor with Therapeutic Potential for Pituitary Tumors

Pituitary tumors of the gonadotrope lineage are often large and invasive, resulting in hypopituitarism. No medical treatments are currently available. Using a combined genetic and genomic screen of individual human gonadotrope pituitary tumor samples, we recently identified the mammalian sterile-20 like kinase 4 (MST4) as a protumorigenic effector, driving increased pituitary cell proliferation and survival in response to a hypoxic microenvironment. To identify novel inhibitors of the MST4 kinase for potential future clinical use, computational-based virtual library screening was used to dock the SelleckChem kinase inhibitor library into the ATP-binding site of the MST4 crystal structure. Several inhibitor candidates were identified with the potential to bind with high affinity. Using a TR-FRET in vitro recombinant kinase assay, hesperadin, initially described as an Aurora kinase inhibitor, exhibited potent inhibition of the MST4 kinase at nanomolar concentrations. The LβT2 gonadotrope pituitary cell hypoxic model was used to test the ability of this inhibitor to antagonize MST4 actions. Under short-term severe hypoxia (1% O2), MST4 protection from hypoxia-induced apoptosis was abrogated in the presence of hesperadin. Similarly, under chronic hypoxia (5%), hesperadin blocked the proliferative and colony-forming actions of MST4 as well as the ability to activate specific downstream signaling and hypoxia-inducible factor-1 effectors. Together, these data identify hesperadin as the first potent, selective inhibitor of the MST4 kinase with the capacity to block pituitary tumor cell growth in a hypoxic microenvironment.

Evaluation of quantitative assays for the identification of direct signal transducer and activator of transcription 3 (STAT3) inhibitors

In many forms of cancer the signal transducer and activator of transcription 3 (STAT3) transcription factor remains constitutively active, driving cancer survival and progression. The critical role of STAT3 in tumorigenesis has prompted a campaign of drug discovery programs to identify small molecules that disrupt the function of STAT3, with more recent efforts focusing on direct STAT3 inhibition. There are two target binding sites for direct STAT3 inhibitors: the SH2 dimerization domain and the DNA-binding domain. An in vitro fluorescence polarization assay, using recombinant STAT3 protein, has successfully identified compounds that target the SH2 domain; however, no assay has been reported to identify inhibitors that bind the DNA-binding domain. The lack of such a quantitative assay has limited the identification and development of STAT3 DNA-binding domain inhibitors. Here, we report a modified DNA-binding ELISA to incorporate recombinant STAT3 protein to evaluate small molecules that prevent STAT3-DNA binding. The concomitant use of the ELISA and fluorescence polarization assay enables the classification of direct STAT3 inhibitors by their site of action. Our data provide further support that niclosamide inhibits STAT3 through interaction with the DNA-binding domain. Furthermore, the ELISA can support medicinal chemistry efforts by identifying DNA-binding domain inhibitors and allowing the determination of an IC50 value, supporting the ranking of inhibitors and development of structure-activity relationships. Therefore, we propose a tandem evaluation approach to identify small molecules that target the SH2 domain or the DNA-binding domain of STAT3, which allows for quantitative evaluation of candidate STAT3 inhibitors.

Model system for irreversible inhibition of Nek2: thiol addition to ethynylpurines and related substituted heterocycles

Recent studies have shown that irreversible inhibition of Nek2 kinase [(Never in mitosis gene a)-related kinase 2], overexpression of which is observed in several cancers, can be achieved using Michael acceptors containing an ethynyl group, which target the enzyme's cysteine 22 residue lying near the catalytic site. The model studies described herein demonstrate an analogous capture of the ethynyl moiety in a series of ethynyl-heterocycles (e.g. 6-ethynyl-N-phenyl-9H-purin-2-amine) by N-acetylcysteine methyl ester in the presence of 1,4-diazabicyclo[2.2.2]octane in either dimethyl sulfoxide or N,N-dimethylformamide. Kinetic studies showed a 50-fold range in reactivity with 7-ethynyl-N-phenyl-3H-[1,2,3]triazolo[4,5-d]pyrimidin-5-amine being the most reactive compound, whereas 4-ethynyl-N-phenyl-7H-pyrrolo[2,3-d]pyrimidin-2-amine was the least reactive. Studies of the isomeric compounds, 2-(3-((6-ethynyl-7-methyl-7H-purin-2-yl)amino)phenyl)acetamide and 2-(3-((6-ethynyl-9-methyl-9H-purin-2-yl)amino)phenyl)acetamide, revealed the N(7)-methyl isomer to be 5-fold more reactive than the 9-methyl isomer, which is ascribed to a buttressing effect in the N(7)-methyl compound. Comparison of the crystal structures of these isomers showed that the ethynyl group is significantly displaced away from the methyl group exclusively in the N(7)-methyl isomer with an sp(2) bond angle of 124°, whereas the corresponding angle in the N(9)-methyl isomer was the expected 120°. The results of this study indicate heterocyclic scaffolds that are likely to be more promising for inhibition of Nek2 and other kinases containing a reactive cysteine.

RSK3: A regulator of pathological cardiac remodeling

The family of p90 ribosomal S6 kinases (RSKs) are pleiotropic effectors for extracellular signal-regulated kinase signaling pathways. Recently, RSK3 was shown to be important for pathological remodeling of the heart. Although cardiac myocyte hypertrophy can be compensatory for increased wall stress, in chronic heart diseases, this nonmitotic cell growth is usually associated with interstitial fibrosis, increased cell death, and decreased cardiac function. Although RSK3 is less abundant in the cardiac myocyte than other RSK family members, RSK3 appears to serve a unique role in cardiac myocyte stress responses. A potential mechanism conferring the unique function of RSK3 in the heart is anchoring by the scaffold protein muscle A-kinase anchoring protein β (mAKAPβ). Recent findings suggest that RSK3 should be considered as a therapeutic target for the prevention of heart failure, a clinical syndrome of major public health significance.

The effect of macrophage colony-stimulating factor on haemopoietic recovery after autologous bone marrow transplantation

Macrophage colony-stimulating factor (M-CSF) is active in the late stages of monocyte maturation, activates mature monocyte-macrophages and enhances their production of various other cytokines. We have examined the effects of a 21 d course of escalating doses of M-CSF purified from human urine (hM-CSF) on recovery following autologous bone marrow transplantation (ABMT) in 20 patients with malignant lymphomas. Four patients were treated at each dose level of 4, 8, 16, 32 and 64 x 10(6) U/m2/d and results compared to 46 concurrent controls. There was no significant difference in recovery to an absolute neutrophil count (ANC) of 0.5 x 10(9)/l (median 20 d in hM-CSF group versus 22 in controls) or in recovery of platelets to 50 x 10(9)/l (32 d versus 39 d, 0.05 less than P less than 0.1); hM-CSF patients received a median of 81 platelet units following ABMT (controls 112 units, P = NS). hM-CSF patients had a median of 5.5 d with fever greater than 37.5 degrees C (control 8, P = NS), received parenteral antibiotics for 14.5 d (control 17, P = NS) and had a 50% incidence of bacteraemia (control 48%). hM-CSF treated patients were discharged by a median of day 29 following transplantation (control 33, P less than 0.05). Platelet and neutrophil recovery correlated significantly with the number of marrow mononuclear cells (MNC) reinfused in the hM-CSF group (P = 0.05 and P = 0.014 respectively) but not in controls. Subgroup analysis showed that hM-CSF patients receiving greater than 2 x 10(8) MNC/kg body weight reached an ANC of 0.5 x 10(9)/l by a median of day 16.5 (control 18.5, NS), became platelet transfusion independent by day 17 (control 29, P less than 0.05) and reached a platelet count of 50 x 10(9)/l by day 21 (control 40, P less than 0.05). No significant toxicity attributable to hM-CSF treatment was seen. These results suggest that hM-CSF accelerates platelet recovery following ABMT and that relatively large marrow innocula are required to see this effect.

Substituted oxindol-3-ylidenes as AMP-activated protein kinase (AMPK) inhibitors

AMP-activated protein kinase (AMPK) is a central metabolic regulator that promotes cancer growth and survival under hypoxia and plays a role in the maintenance of cancer stem cells. A major challenge to interrogating the potential of targeting AMPK in cancer is the lack of potent and selective small molecule inhibitors. Compound C has been widely used as an AMPK inhibitor, but it lacks potency and has a poor selectivity profile. The multi-kinase inhibitor, sunitinib, has demonstrated potent nanomolar inhibition of AMPK activity and has scope for modification. Here, we have designed and synthesized several series of oxindoles to determine the structural requirements for AMPK inhibition and to improve selectivity. We identified two potent, novel oxindole-based AMPK inhibitors that were designed to interact with the DFG motif in the ATP-binding site of AMPK, this key feature evades interaction with the common recptor tyrosine kinase targets of sunitinib. Cellular engagement of AMPK by these oxindoles was confirmed by the inhibition of phosphorylation of acetyl-CoA carboxylase (ACC), a known substrate of AMPK, in myeloid leukemia cells. Interestingly, although AMPK is highly expressed and activated in K562 cells these oxindole-based AMPK inhibitors did not impact cell viability or result in significant cytotoxicity. Our studies serve as a platform for the further development of oxindole-based AMPK inhibitors with therapeutic potential.