Cryptic splicing events in the iron transporter ABCB7 and other key target genes in SF3B1-mutant myelodysplastic syndromes

The splicing factor SF3B1 is the most frequently mutated gene in myelodysplastic syndromes (MDS), and is strongly associated with the presence of ring sideroblasts (RS). We have performed a systematic analysis of cryptic splicing abnormalities from RNA sequencing data on hematopoietic stem cells (HSCs) of SF3B1-mutant MDS cases with RS. Aberrant splicing events in many downstream target genes were identified and cryptic 3' splice site usage was a frequent event in SF3B1-mutant MDS. The iron transporter ABCB7 is a well-recognized candidate gene showing marked downregulation in MDS with RS. Our analysis unveiled aberrant ABCB7 splicing, due to usage of an alternative 3' splice site in MDS patient samples, giving rise to a premature termination codon in the ABCB7 mRNA. Treatment of cultured SF3B1-mutant MDS erythroblasts and a CRISPR/Cas9-generated SF3B1-mutant cell line with the nonsense-mediated decay (NMD) inhibitor cycloheximide showed that the aberrantly spliced ABCB7 transcript is targeted by NMD. We describe cryptic splicing events in the HSCs of SF3B1-mutant MDS, and our data support a model in which NMD-induced downregulation of the iron exporter ABCB7 mRNA transcript resulting from aberrant splicing caused by mutant SF3B1 underlies the increased mitochondrial iron accumulation found in MDS patients with RS.

Suicide risk linked with clinical consultation frequency, psychiatric diagnoses and psychotropic medication prescribing in a national study of primary-care patients

BACKGROUND

Little is known about the precursors of suicide risk among primary-care patients. This study aimed to examine suicide risk in relation to patterns of clinical consultation, psychotropic drug prescribing, and psychiatric diagnoses.

METHOD

Nested case-control study in the Clinical Practice Research Datalink (CPRD), England. Patients aged ⩾16 years who died by suicide during 2002-2011 (N = 2384) were matched on gender, age and practice with up to 20 living control patients (N = 46 899).

RESULTS

Risk was raised among non-consulting patients, and increased sharply with rising number of consultations in the preceding year [⩾12 consultations v. 1: unadjusted odds ratio (OR) 6.0, 95% confidence interval (CI) 4.9-7.3]. Markedly elevated risk was also associated with the prescribing of multiple psychotropic medication types (⩾5 types v. 0: OR 62.6, CI 44.3-88.4) and with having several psychiatric diagnoses (⩾4 diagnoses v. 0: OR 31.1, CI 19.3-50.1). Risk was also raised among patients living in more socially deprived localities. The confounding effect of multiple psychotropic drug types largely accounted for the rising risk gradient observed with increasing consultation frequency.

CONCLUSIONS

A greater proportion of patients with several psychiatric diagnoses, those prescribed multiple psychotropic medication types, and those who consult at very high frequency might be considered for referral to mental health services by their general practitioners. Non-consulters are also at increased risk, which suggests that conventional models of primary care may not be effective in meeting the needs of all people in the community experiencing major psychosocial difficulties.

A Novel Gaba Receptor on Central Neurones

The features of γ-aminobutyric acid (GABA) as an inhibitory neurotransmitter are described, together with those of its receptor as defined by both iontophoretic and radiolabelled ligand binding techniques. Evidence is presented supporting the existence of a second GABA receptor at both peripheral nerve endings and within the CNS. At the classical receptor, GABA can produce a depolarisation of the ganglion cell body or mediate hyperpolarisation within the CNS by increasing membrane conductance to chloride ions. At this second receptor GABA acts in a bicuculline-insensitive manner to reduce neurotransmitter outflow.

Many GABA analogues active at the classical receptor are inactive at the second receptor but by contrast baclofen which is inactive at the classical receptor is a potent agonist at the novel site.

Two-Plasmon Decay Mitigation in Direct-Drive Inertial-Confinement-Fusion Experiments Using Multilayer Targets

Multilayer direct-drive inertial-confinement-fusion targets are shown to significantly reduce two-plasmon decay (TPD) driven hot-electron production while maintaining high hydrodynamic efficiency. Implosion experiments on the OMEGA laser used targets with silicon layered between an inner beryllium and outer silicon-doped plastic ablator. A factor-of-5 reduction in hot-electron generation (>50  keV) was observed in the multilayer targets relative to pure CH targets. Three-dimensional simulations of the TPD-driven hot-electron production using a laser-plasma interaction code (lpse) that includes nonlinear and kinetic effects show good agreement with the measurements. The simulations suggest that the reduction in hot-electron production observed in the multilayer targets is primarily caused by increased electron-ion collisional damping.

Abstract P5-08-17: A study of c-Jun N-terminal kinase (JNK) and c-Jun as biomarkers in early breast cancer

Background

The AP-1 transcription factor c-Jun is a key downstream target of c-Jun N-terminal kinase (JNK) which mediates intracellular signalling associated with a variety of cellular functions. The JNK pathway in breast cancer (BC) can be attenuated via loss of function mutations in MAPK kinases as well as via PIK3CA mutations; however, there is contradictory information about the role of JNK pathway and its clinical implications in BC.

Methods

In the current study, the clinicopathological implications of JNK and JUN mRNA expressions were evaluated in multiple independent BC datasets: a) Training-set (Uppsala cohort; n=249), b) Test-set (human genome atlas database; n=540), c) External validation-set (METABRIC cohort; n=1952) and d) Multicentre pooled databases (n=5530). The clinicopathological associations of their phosphorylated proteins (p-Jnk and p-c-Jun) were assessed in the Nottingham Tenovus Primary BC Series (n= 1650) and in an ER negative cohort (n=450).

Results

Both JNK and c-JUN mRNA high expressions were significantly associated with PAM50-Luminal A and ER+/HER2-/low proliferation molecular BC subtypes, tubular/lobular types, and integrative molecular clusters 4 (IntClust.4), ps<0.001. Whereas BC that had both low JNK and c-JUN mRNA, were significantly associated with large tumour size, high grade, absence of hormonal receptors (HR), HER2 overexpression, PAM50 HER2 and PAM50 Basal molecular subtypes, and IntClust.1, 9 and 10 BCs; ps<0.001.

There was a significant positive correlations between p-Jnk and p-c-Jun protein levels (p<0.0001), however; our data suggested that differential p-Jnk/p-c-Jun expression may influence BC phenotypes. BC with p-Jnk-ve/p-c-Jun-ve were associated with the most aggressive phenotypes including largest tumour size, highest grade, lympho-vascular invasion, absence of HR, basal-like-phenotype, HER2 overexpression, and loss of double strand , single stand and base excision DNA repair proteins (ps<0.0001). In addition p-Jnk-ve/ pc-Jun-ve phenotype was associated with the lowest levels of p-38, ATF2, and p-ATF2; ps<0.001. Interestingly, low levels of either c-JUN-mRNA or pc-Jun protein, was associated with, PAM50-luminal B, epithelial mesenchymal transition and TP53 mutation and loss of its downstream proteins such as MDM2, MDM4, Bcle2 and p21; ps<0.05.

JNK+ (mRNA and p-Jnk) and c-JUN+ (mRNA and p-c-Jun) individually were associated with prolonged BC specific survival (ps<0.001). Multivariate cox regression models that included other validated prognostic factors and therapies revealed that c-JUN-mRNA (Uppsala: p=0.005 and METABIRIC: p=0.036) and p-c-Jun (HR: 0.69; 95% CI = 0.55-0.88; p=0.002) were independently associated with clinical outcome. Furthermore, in ER+ high risk BC, exposure to tamoxifen was associated with decreased risk of death from BC in those patients with p-c-Jun-ve BC (HR: 0.65; 95% CI: 0.45-0.95; p=0.025).

Conclusion

JNK and c-JUN mRNA as well as p-Jnk and p-c-Jun protein levels are associated with luminal BC, with p-c-Jun being found to be an independent prognostic factor. The interaction between p-Jnk, p-c-Jun and TP53 mutation could predict response to endocrine therapy in ER+ BC. The role of the transcriptionally active form of c-JUN warrants further investigation with regard to its role in BC.

Citation Format: Palmieri C, Rudraraju B, Giannoudis A, Moore D, Shaw J, Chan S, Ellis IO, Caldas C, Coombes RC, Carroll JS, Ali S, Abdel-Fatah TMA. A study of c-Jun N-terminal kinase (JNK) and c-Jun as biomarkers in early breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-08-17.

Clinical profile of diabetic ketoacidosis in tertiary hospitals in China: a multicentre, clinic-based study

AIMS

To evaluate the clinical profile of patients with diabetic ketoacidosis in tertiary hospitals in China.

METHODS

A retrospective study of patients hospitalized with diabetic ketoacidosis between 2010 and 2012 was carried out in 15 tertiary hospitals around China. Clinical and laboratory data were collected. Patients were classified based on clinical diagnosis and treatment history. Groups were compared for differences in vital statistics and biochemical profiles at presentation.

RESULTS

The study comprised 643 patients with diabetic ketoacidosis: 308 patients (47.9%) with Type 1 diabetes, 294 patients (45.7%) with Type 2 diabetes and 41 patients (6.4%) with atypical diabetes. Three hundred and eighty-eight diabetic ketoacidosis episodes (60.3%) were in patients with known diabetes. The most common precipitating factor was infection (40.1%), followed by unknown causes (36.9%) and non-compliance with anti-diabetes treatment (16.8%). At presentation, gastrointestinal symptoms and dehydration were more common in the Type 1 diabetes group. For new-onset diabetes, only 74.4% and 55.9% of patients were evaluated for β-cell function and autoantibodies for classification. Only 67% of patients with diabetic ketoacidosis received appropriate fluid therapy and 56% patients with severe acidosis received bicarbonate therapy. The length of hospital stay was 10.0 (7.0-14.0) days. The mortality rate was 1.7%, and was much higher in Type 2 diabetes than that in Type 1 diabetes (3.2% vs. 0.4%, P < 0.01).

CONCLUSIONS

Type 2 and Type 1 diabetes contribute to a similar proportion of cases presenting with diabetic ketoacidosis in China. Admissions with diabetic ketoacidosis are still associated with significant mortality and prolonged hospitalization. The efficiency of diabetic ketoacidosis management needs to be improved by implementing the updated guidelines.

Cognitive-behavioural suicide prevention for male prisoners: a pilot randomized controlled trial

BACKGROUND

Prisoners have an exceptional risk of suicide. Cognitive-behavioural therapy for suicidal behaviour has been shown to offer considerable potential, but has yet to be formally evaluated within prisons. This study investigated the feasibility of delivering and evaluating a novel, manualized cognitive-behavioural suicide prevention (CBSP) therapy for suicidal male prisoners.

METHOD

A pilot randomized controlled trial of CBSP in addition to treatment as usual (CBSP; n = 31) compared with treatment as usual (TAU; n = 31) alone was conducted in a male prison in England. The primary outcome was self-injurious behaviour occurring within the past 6 months. Secondary outcomes were dimensions of suicidal ideation, psychiatric symptomatology, personality dysfunction and psychological determinants of suicide, including depression and hopelessness. The trial was prospectively registered (number ISRCTN59909209).

RESULTS

Relative to TAU, participants receiving CBSP therapy achieved a significantly greater reduction in suicidal behaviours with a moderate treatment effect [Cohen's d = -0.72, 95% confidence interval -1.71 to 0.09; baseline mean TAU: 1.39 (S.D. = 3.28) v. CBSP: 1.06 (S.D. = 2.10), 6 months mean TAU: 1.48 (S.D. = 3.23) v. CBSP: 0.58 (S.D. = 1.52)]. Significant improvements were achieved on measures of psychiatric symptomatology and personality dysfunction. Improvements on psychological determinants of suicide were non-significant. More than half of the participants in the CBSP group achieved a clinically significant recovery by the end of therapy, compared with a quarter of the TAU group.

CONCLUSIONS

The delivery and evaluation of CBSP therapy within a prison is feasible. CBSP therapy offers significant promise in the prevention of prison suicide and an adequately powered randomized controlled trial is warranted.

Identification of a lead like inhibitor of the hepatitis C virus non-structural NS2 autoprotease

Hepatitis C virus (HCV) non-structural protein 2 (NS2) encodes an autoprotease activity that is essential for virus replication and thus represents an attractive anti-viral target. Recently, we demonstrated that a series of epoxide-based compounds, previously identified as potent inhibitors of the clotting factor, FXIII, also inhibited NS2-mediated proteolysis in vitro and possessed anti-viral activity in cell culture models. This suggested that a selective small molecule inhibitor of the NS2 autoprotease represents a viable prospect. In this independent study, we applied a structure-guided virtual high-throughput screening approach in order to identify a lead-like small molecule inhibitor of the NS2 autoprotease. This screen identified a molecule that was able to inhibit both NS2-mediated proteolysis in vitro and NS2-dependent genome replication in a cell-based assay. A subsequent preliminary structure–activity relationship (SAR) analysis shed light on the nature of the active pharmacophore in this compound and may inform further development into a more potent inhibitor of NS2 mediated proteolysis.

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In silico screening identified a small molecule inhibitor of hepatitis C virus NS2 autoprotease in vitro.

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This compound showed specific inhibition of NS2-NS3 autocleavage dependent HCV genome replication in a cell based assay.

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NS2 protease is a valid target for further drug development.

The moderating effects of coping and self-esteem on the relationship between defeat, entrapment and suicidality in a sample of prisoners at high risk of suicide

BACKGROUND

Research is sparse which examines pathways to suicide, and resilience to suicide, in people who are particularly vulnerable to suicide, for example, prison inmates. The purpose of this study was to examine the ways in which perceptions of self-esteem and coping ability interacted with defeat and entrapment to both amplify suicidal thoughts and feelings, and to act as a buffer against suicidal thoughts and feelings.

METHODS

Participants were 65 male prisoners at high risk of suicide. A cross-sectional questionnaire design was used. Questionnaire measures of depression, defeat, entrapment, self-esteem, coping ability and suicidal probability were administered.

RESULTS

For the hopelessness component of the suicide probability measure, high levels of coping ability together with low levels of defeat resulted in the lowest levels of suicidality indicative of a resilience factor. In contrast, low levels of coping skills together with high levels of entrapment were a high risk factor for this hopelessness component of suicide. This pattern of results pertained when controlling for depression levels.

CONCLUSIONS

This is the first study to examine interactions between defeat, entrapment and appraisals of self-esteem and coping ability. Therapeutic interventions would benefit from boosting perceptions and appraisals of coping ability, in particular, in people who are at high risk for suicide.