Flotillins as regulators of ErbB2 levels in breast cancer.

Amplification and overexpression of the receptor tyrosine kinase ErbB2 occur in up to 30% of human breast cancers, and high ErbB2 levels are correlated with poor prognosis for breast cancer patients. In contrast to the epithelial growth factor receptor (ErbB1), ErbB2 is not downregulated by ligand-induced mechanisms. Here we show that flotillins are involved in the stabilization of ErbB2 at the plasma membrane. In SKBR3 breast cancer cells and breast cancer tissue, a positive correlation between flotillin and ErbB2 expression levels could be demonstrated. Moreover, the tissue microarray analyses of biopsies from 194 patients diagnosed with carcinomas of the breast showed that flotillin-2 emerged as a potential predictor of prognosis in breast cancer. Depletion of flotillin-1 and flotillin-2 leads to internalization and degradation of ErbB2. Furthermore, flotillin-1 and -2 were found to be in a molecular complex with ErbB2 and Hsp90. The depletion of one of these proteins results in disruption of this complex, followed by destabilization of ErbB2 at the membrane, and its internalization and degradation. As a consequence, ErbB2-triggered downstream signalling is inhibited. Our data demonstrate a novel mechanism for interfering with ErbB2 signalling, which potentially can have clinical impact.

Individual and social environment influences on smoking in children and adolescents.

OBJECTIVES: A precise knowledge of the risk factors for childhood and adolescent smoking is crucial for the development of appropriate preventive measures. This study investigated current smoking prevalence and the social and regional correlates for smoking among minors (children and adolescents aged 12-17 years) in Germany. METHODS: Bivariate data analysis was performed on the basis of a representative national cross-sectional study performed in 2004, and multivariable logistic regression models were calculated separately for boys and girls. All correlates identified as significant in the bivariate model were used in the multivariable analysis. STUDY DESIGN: The database used in this research was from the study 'Drug Affinity of Young People in the Federal Republic of Germany 2004', with approximately 1298 children and adolescents aged 12-17 years. RESULTS: Twelve percent of male and 9% of female adolescents in Germany reported that they are habitual smokers, and 12% of male and 13% of female adolescents reported that they are occasional smokers. Multivariable data analysis shows that living in a large city is protective for adolescents in terms of local disparities. The educational level of the respondents also correlates significantly with smoking behaviour. The percentage of adolescent smokers is lowest among those with a high level of education. The presence of smokers in the household is associated with a significantly higher prevalence of smoking among adolescents compared with those growing up in a non-smoking household. CONCLUSION: Smoking is a major public health problem among German children and adolescents. Control measures must tackle the structural and social pressures that shape smoking behaviour during childhood.

Interventions to prevent overweight in children.

There are only few controlled studies on prevention of overweight in children and adolescence. These studies differ with respect to strategy, setting, duration, focus, variables of outcome and statistical power. Universal and school-based interventions show some improvement of health knowledge and health-related behaviours but they have only minor or no effects on nutritional status. However they reduce the incidence of overweight. The effects seem to be more pronounced in girls than in boys. Children of middle and high class as well as children with intact families benefit better from intervention than children with low socioeconomic status. Selected prevention in overweight children was most successful when children were treated together with their parents. However there are social barriers limiting the success. Simple interventions in a single area are unlikely to work on their own. The development of effective preventive interventions likely require strategies that affect multiple settings simultaneously. At present there is no concerted action but many strategies are followed in isolation. There is need for national campaigns and action plans on childhood overweight and obesity. It is tempting to speculate that this will also increase the effects of isolated approaches.

First lessons from the Kiel Obesity Prevention Study (KOPS).

AIMS: Prevention of obesity is a public health agenda. There are only few longitudinal studies on prevention of overweight in children. The Kiel Obesity Prevention Study (KOPS) intends to characterise the determinants of childhood overweight and the effect of preventive measures within schools as well as within families. METHODS: Between 1996 and 2005, KOPS investigated 4997 German 5-7 and 4487 9-11-y-old children or 41 and 37% of the total population of all first and fourth graders in 32 primary schools in Kiel (248 000 inhabitants), northwest Germany. Main outcome measures were nutritional status, health habits and risk factors of disease. In addition, health promotion was performed each year in three schools for all first graders and their teachers (nutrition education and active school breaks) together with a family-oriented approach in families with obese and preobese children. Up to now, the children were followed for 4y and were reinvestigated at age 10 y. RESULTS: The KOPS population was representative for all 5-7 and 9-11-y-old children in Kiel. The prevalence of overweight/ obesity (> or = 90th/97th BMI reference percentile) was 7.0/5.8 and 11.3/6.3% in 5-7 and 9-11-y-old children, respectively. Parental overweight, a low socio-economic status and a high birth weight were identified as main risk factors for overweight in prepubertal children. The first results of the interventions show that obesity prevention was possible, but there were limited success rates in boys and children from low social class. CONCLUSION: Faced with the environmental contributors to the obesity problem societal rather than individual responsibilities are evident. This idea suggests that dissecting and tackling the obesogenic environment is necessary to complement school- and family-based interventions.

Structural analysis and molybdenum-dependent expression of the pAO1-encoded nicotine dehydrogenase genes of Arthrobacter nicotinovorans.

The genes of nicotine dehydrogenase (NDH) were identified, cloned and sequenced from the catabolic plasmid pAO1 of Arthrobacter nicotinovorans. In immediate proximity to this gene cluster is the beginning of the 6-hydroxy-L-niotine oxidase (6-HLNO) gene. NDH is composed of three subunits (A, B and C) of M(r) 30,011, 14,924 and 87,677. It belongs to a family of bacterial hydroxylases with a similar subunit structure; they have molybdopterin dinucleotide, FAD and Fe-S clusters as cofactors. Here the first complete primary structure of a bacterial hydroxylase is provided. Sequence alignments of each of the NDH subunits show similarities to the sequences of eukaryotic xanthine dehydrogenase (XDH) but not to other known molybdenum-containing bacterial enzymes. Based on alignment with XDH it is inferred that the smallest subunit (NDHB) carries an iron-sulphur cluster, that the middle-sized subunit (NDHA) binds FAD, and that the largest NDH subunit (NDHC) corresponds to the molybdopterin-binding domain of XDH. Expression of both the ndh and the 6-hino genes required the presence of nicotine and molybdenum in the culture medium. Tungsten inhibited enzyme activity but not the synthesis of the enzyme protein. The enzyme was found in A. nicotinovorans cells in a soluble form and in a membrane-associated form. In the presence of tungsten the fraction of membrane-associated NDH increased.

13C, 15N, and 31P NMR studies on 6-hydroxy-L-nicotine oxidase from Arthrobacter oxidans.

The interaction between the apoprotein of 6-hydroxy-L-nicotine oxidase from Arthrobacter oxidans and the prosthetic group FAD has been investigated by 13C, 15N, and 31P NMR techniques. The FAD prosthetic group was selectively enriched in 13C and 15N isotopes by adding isotopically labeled riboflavin derivatives to the growth medium of riboflavin-requiring mutant cells. In the oxidized state the chemical shift of the C(7) and C(8) atoms indicates that the xylene moiety of the isoalloxazine ring is embedded in a hydrophobic environment. The polarization of the isoalloxazine ring as a whole is, however, much more comparable to that of free flavin in a polar and protic environment than to free flavin in an apolar environment. The polarization of the ring system can be ascribed to strong hydrogen bonds between the apoprotein and the two carbonyl groups. The binding of the competitive inhibitor, 6-hydroxy-D-nicotine, influences the resonances of the C(4a) and the N(5) atoms strongly. It is suggested that these shifts are due to a strong hydrogen-bonding interaction between the N(5) atom and the inhibitor. On reduction all resonances, except those of the C(10a) and the N(1) atoms, shift upfield, indicating the increased electron density in the ring system. In the dithionite-reduced enzyme, the ring system is bent at the N(5) position. Due to the bending of the N(5) atom and the sp2 hybridized N(10) atom, electron density from the N(10) atom is reallocated at the C(4) carbonyl group. In contrast, in the substrate-reduced enzyme the N(5) atom is almost completely sp2 hybridized, yielding a rather planar isoalloxazine ring.(ABSTRACT TRUNCATED AT 250 WORDS)