Structural basis of high-order oligomerization of the cullin-3 adaptor SPOP.

Protein ubiquitination in eukaryotic cells is mediated by diverse E3 ligase enzymes that each target specific substrates. The cullin E3 ligase complexes are the most abundant class of E3 ligases; they contain various cullin components that serve as scaffolds for interaction with substrate-recruiting adaptor proteins. SPOP is a BTB-domain adaptor of the cullin-3 E3 ligase complexes; it selectively recruits substrates via its N-terminal MATH domain, whereas its BTB domain mediates dimerization and interactions with cullin-3. It has recently been recognized that the high-order oligomerization of SPOP enhances the ubiquitination of substrates. Here, a dimerization interface in the SPOP C-terminus is identified and it is shown that the dimerization interfaces of the BTB domain and of the C-terminus act independently and in tandem to generate high-order SPOP oligomers. The crystal structure of the dimeric SPOP C-terminal domain is reported at 1.5 Å resolution and it is shown that Tyr353 plays a critical role in high-order oligomerization. A model of the high-order SPOP oligomer is presented that depicts a helical organization that could enhance the efficiency of substrate ubiquitination

Phase i trial of axitinib combined with platinum doublets in patients with advanced non-small cell lung cancer and other solid tumours

BACKGROUND: This phase I dose-finding trial evaluated safety, efficacy and pharmacokinetics of axitinib, a potent and selective secondgeneration inhibitor of vascular endothelial growth factor receptors, combined with platinum doublets in patients with advanced non-small cell lung cancer (NSCLC) and other solid tumours. METHODS: In all, 49 patients received axitinib 5mg twice daily (b.i.d.) with paclitaxel/carboplatin or gemcitabine/cisplatin in 3-week cycles. Following determination of the maximum tolerated dose, a squamous cell NSCLC expansion cohort was enroled and received axitinib 5mg b.i.d. with paclitaxel/carboplatin. RESULTS: Two patients experienced dose-limiting toxicities: febrile neutropenia (n¼1) in the paclitaxel/carboplatin cohort and fatigue (n¼1) in the gemcitabine/cisplatin cohort. Common nonhaematologic treatment-related adverse events were hypertension (36.7%), diarrhoea (34.7%) and fatigue (28.6%). No gradeX3 haemoptysis occurred among 12 patients with squamous cell NSCLC. The objective response rate was 37.0% for patients receiving axitinib/paclitaxel/carboplatin (n¼27) and 23.8% for patients receiving axitinib/gemcitabine/cisplatin (n¼21). Pharmacokinetics of axitinib and chemotherapeutic agents were similar when administered alone or in combination. CONCLUSION: Axitinib 5mg b.i.d. may be combined with standard paclitaxel/carboplatin or gemcitabine/cisplatin regimens without evidence of overt drug–drug interactions. Both combinations demonstrated clinical efficacy and were well tolerated.This study was sponsored by Pfizer Inc. Support was provided in part by National Institutes of Health grant P30 CA006927 to the Fox Chase Cancer Center. We thank the patients who participated in this study and the physicians who referred them, as well as the study coordinators and data managers, Shelley Mayfield and Carol Martins at Pfizer Inc. for support of the study conduct, and Gamal ElSawah, Pfizer Medical Affairs, for his review of the manuscript. Medical writing support was provided by Joanna Bloom, of UBC Scientific Solutions (Southport, CT, USA) and Christine Arris at ACUMED (Tytherington, UK) and was funded by Pfizer In

The structure of the Bach2 POZ-domain dimer reveals an intersubunit disulfide bond.

Bach2 is a transcriptional repressor that is expressed during specific stages of B-cell development and in neuronal cells. It plays a critical role in modulating class-switch recombination during the differentiation of mature B cells to antibody-secreting plasma cells and it is also an important regulator of apoptotic responses to oxidative stress. Bach2 has been implicated both as an oncogene and as a tumour suppressor in human malignancy. The interaction of Bach2 with its target genes is mediated via its basic leucine-zipper region, whereas the N-terminal POZ domain recruits transcriptional co-repressors and class II histone deacetylases. Here, the crystal structure of the human Bach2 POZ domain is reported at 2.1 Å resolution. The Bach2 POZ-domain dimer resembles the POZ-domain dimers of the POZ zinc finger transcription factors and dimerization is independent of an N-terminal region that has previously been implicated in the dimerization of the POZ basic leucine-zipper protein Bach1. The Bach2 POZ domain crystallized in two forms which differed by the presence of an intersubunit disulfide bond. The intersubunit disulfide bond is present both in bacterially expressed Bach2 POZ domain in solution and in protein expressed in transfected eukaryotic cells. These crystal structures will be relevant for understanding the regulation of Bach2 in response to oxidative stress and for the design of therapeutics that target the Bach2 POZ domain in human malignancy

Lower levels of cigarette consumption found in smoke-free workplaces in California.

ObjectiveWe examined the relationship between workplace smoking policies and smoking prevalence and cigarette consumption.MethodsCalifornia residents were questioned by telephone with the 1990 California Tobacco Survey. All respondents (11,704) above age 18 years who were employed indoors were used. Respondents were asked about smoking status, workplace smoking policy, desire to quit, and smoking history. Logistic regression was used to determine the relationship of workplace smoking policy to smoking status, accounting for demographic variables.ResultsPrevalence of regular smokers was significantly lower in smoke-free workplaces than in those with no restrictions (13.7% vs 20.6%, P < .001). Continuing regular smokers in smoke-free workplaces smoked fewer cigarettes than those in workplaces with no restrictions (296 vs 341 packs per year, P < .001). More comprehensive smoking policies were associated with smokers more likely to contemplate quitting (P = .014).ConclusionsEmployees in smoke-free workplaces have a lower smoking prevalence and, among continuing smokers, lower cigarette consumption than individuals working where smoking is permitted. We estimate cigarette consumption among employees indoors is 21% below that if there were no smoking restrictions in California workplaces. Furthermore, if all California workplaces were smoke-free, cigarette consumption among employees would be 41% below that if there were no workplace smoking restrictions, approximately a $406 million annual loss in sales to the tobacco industry. This study supports the hypothesis that smoke-free workplace policies are an effective public health measure for decreasing smoking prevalence and cigarette consumption among continuing smokers

Lower levels of cigarette consumption found in smoke-free workplaces in California.

ObjectiveWe examined the relationship between workplace smoking policies and smoking prevalence and cigarette consumption.MethodsCalifornia residents were questioned by telephone with the 1990 California Tobacco Survey. All respondents (11,704) above age 18 years who were employed indoors were used. Respondents were asked about smoking status, workplace smoking policy, desire to quit, and smoking history. Logistic regression was used to determine the relationship of workplace smoking policy to smoking status, accounting for demographic variables.ResultsPrevalence of regular smokers was significantly lower in smoke-free workplaces than in those with no restrictions (13.7% vs 20.6%, P < .001). Continuing regular smokers in smoke-free workplaces smoked fewer cigarettes than those in workplaces with no restrictions (296 vs 341 packs per year, P < .001). More comprehensive smoking policies were associated with smokers more likely to contemplate quitting (P = .014).ConclusionsEmployees in smoke-free workplaces have a lower smoking prevalence and, among continuing smokers, lower cigarette consumption than individuals working where smoking is permitted. We estimate cigarette consumption among employees indoors is 21% below that if there were no smoking restrictions in California workplaces. Furthermore, if all California workplaces were smoke-free, cigarette consumption among employees would be 41% below that if there were no workplace smoking restrictions, approximately a $406 million annual loss in sales to the tobacco industry. This study supports the hypothesis that smoke-free workplace policies are an effective public health measure for decreasing smoking prevalence and cigarette consumption among continuing smokers