Mouse mammary tumor virus : a model system for regulation of gene expression

Mouse mammary tumor virus (MMTV) kommt prizipiell in zwei Formen vor. Erstens als integierte virale DNA (endogen vererbt), die in allen Zellen der Maus enthalten ist und zweitens als infektiöse Form, bei der sich die DNA nur im Kern von Brustdrüsenzellen integriert. Die erste Form verhält sich wie ein stummes Gen während die zweite Form aktiv ist, durch Glukocorticoide stimuliert wird und zum Mamma-Karzinom führt. Wir haben beide Typen von viralen Genen molekular geklont und durch Transfektion in verschiedene Zellen in Gewebekultur eingeführt. Wir konnten zeigen, dass sowohl die endogene DNA, wie dir infektiöse DNA in transfektieren Zellen aktiv ist und dass die Expression beider Gene durch Glukocorticoide stimuliert wird. Wir konnten die DNA Squenzen, die für dir Homonstimulierung nötig sind, in einem kleinen Fragment der viralen DNA lokalisieren. Bei der Sequenzanalyse dieses DNA-Stückes haben wir ein neues virales Gen entdeckt, das dir Information für ein Protein von ca. 40000 Moleklargewicht enthählt. Mit Hilfe eines Antikörpers suchen wir in verschiedenen Brustdrüsenzellen und Tumoren nach diesem Proetin, dessen Funktion noch nicht bekannt ist.

Genome-wide association study for coronary artery calcification with follow-up in myocardial infarction.

BACKGROUND: Coronary artery calcification (CAC) detected by computed tomography is a noninvasive measure of coronary atherosclerosis, which underlies most cases of myocardial infarction (MI). We sought to identify common genetic variants associated with CAC and further investigate their associations with MI. METHODS AND RESULTS: Computed tomography was used to assess quantity of CAC. A meta-analysis of genome-wide association studies for CAC was performed in 9961 men and women from 5 independent community-based cohorts, with replication in 3 additional independent cohorts (n=6032). We examined the top single-nucleotide polymorphisms (SNPs) associated with CAC quantity for association with MI in multiple large genome-wide association studies of MI. Genome-wide significant associations with CAC for SNPs on chromosome 9p21 near CDKN2A and CDKN2B (top SNP: rs1333049; P=7.58×10(-19)) and 6p24 (top SNP: rs9349379, within the PHACTR1 gene; P=2.65×10(-11)) replicated for CAC and for MI. Additionally, there is evidence for concordance of SNP associations with both CAC and MI at a number of other loci, including 3q22 (MRAS gene), 13q34 (COL4A1/COL4A2 genes), and 1p13 (SORT1 gene). CONCLUSIONS: SNPs in the 9p21 and PHACTR1 gene loci were strongly associated with CAC and MI, and there are suggestive associations with both CAC and MI of SNPs in additional loci. Multiple genetic loci are associated with development of both underlying coronary atherosclerosis and clinical events.

Transcription factors link mouse WAP-T mammary tumors with human breast cancer.

Mouse models are important tools to decipher the molecular mechanisms of mammary carcinogenesis and to mimic the respective human disease. Despite sharing common phenotypic and genetic features, the proper translation of murine models to human breast cancer remains a challenging task. In a previous study we showed that in the SV40 transgenic WAP-T mice an active Met-pathway and epithelial-mesenchymal characteristics distinguish low- and high-grade mammary carcinoma. To assign these murine tumors to corresponding human tumors we here incorporated the analysis of expression of transcription factor (TF) coding genes and show that thereby a more accurate interspecies translation can be achieved. We describe a novel cross-species translation procedure and demonstrate that expression of unsupervised selected TFs, such as ELF5, HOXA5 and TFCP2L1, can clearly distinguish between the human molecular breast cancer subtypes-or as, for example, expression of TFAP2B between yet unclassified subgroups. By integrating different levels of information like histology, gene set enrichment, expression of differentiation markers and TFs we conclude that tumors in WAP-T mice exhibit similarities to both, human basal-like and non-basal-like subtypes. We furthermore suggest that the low- and high-grade WAP-T tumor phenotypes might arise from distinct cells of tumor origin. Our results underscore the importance of TFs as common cross-species denominators in the regulatory networks underlying mammary carcinogenesis.

Traitements des facteurs de risque cardiovasculaire et dépistage de la maladie coronarienne dans le diabète de type 2 [Treatments for cardiovascular risk factors and screening for coronary artery disease in type 2 diabetes mellitus]

The recent ACCORD and DIAD studies revealed results which could modify treatments and the screening of diabetes vascular complications. Indeed, ACCORD shows no benefit on the prevention of diabetes vascular complications by aggressive treatment of hypertension or the combined treatment of the dyslipidemia. The intensive treatment of the blood glucose, if associated with severe hypoglycemias, increases mortality. DIAD revealed 20% of silent myocardial ischaemia in diabetic patients but no beneficial effect on the cardiovascular mortality. A careful reading of these studies in the light of long term studies such as UKPDS and STENO reveals that these negative results are generated by a too short follow-up and too aggressive objectives. The long term studies reveal that more realistic objectives remain beneficial.

Complete Nucleotide Sequence of Mouse Mammary Tumor Virus from JYG Chinese Wild Mice: Absence of Bacterial Insertion Sequences in the Cloned Viral gag Gene.

Mammary tumors of a newly isolated strain of Chinese wild mouse (JYG mouse) harbor exogenous mouse mammary tumor virus (MMTV). The complete nucleotide sequence of exogenous JYG-MMTV was determined on the proviral 5' long terminal repeat (LTR)(partial)-gag-pol-env-3' LTR (partial) fragment cloned into a plasmid vector and the cDNA sequence from JYG-MMTV producing cells. Similarly to the other MMTV species the LTR of JYG-MMTV contains an open reading frame (ORF). The amino acid sequence of the JYG-MMTV ORF resembles that of SW-MMTV (92% identity) and endogenous Mtv-7 (93% identity) especially at the C-terminal region. Thus, a functional similarity in T-cell receptor V beta recognition as a superantigen is implicated among these MMTV species. Analysis of the viral gag nucleotide sequence revealed that this gene is not disrupted by the bacterial insertion sequence IS1 or IS2, which have been reported to be present in the majority of the plasmids containing the gag region. Comparison of amino acid sequences of JYG-MMTV with those of BR6-MMTV showed that over 96% of the amino acids of gag, pol, protease and env products are identical. These results suggest the intact nature of the nucleotide sequence of the near full-length MMTV genome cloned in the plasmid.

Immune response to mouse mammary tumour virus.

Superantigens of mouse mammary tumor virus induce a strong cognate interaction between T cells and B cells. In addition to amplifying the virus-infected B-cell pool, this superantigen-driven interaction leads to the differentiation of virus-specific B cells into plasma cells. Successful interaction between T cells and B cells is required for completion of the viral life cycle.

Superantigen-reactive CD4+ T cells are required to stimulate B cells after infection with mouse mammary tumor virus.

Superantigens are defined by their ability to stimulate a large fraction of T cells via interaction with the T cell receptor (TCR) V beta domain. Endogenous superantigens, classically termed minor lymphocyte-stimulating (Mls) antigens, were recently identified as products of open reading frames (ORF) in integrated proviral copies of mouse mammary tumor virus (MMTV). We have described an infectious MMTV homologue of the classical endogenous superantigen Mls-1a (Mtv-7). The ORF molecules of both the endogenous Mtv-7 and the infectious MMTV(SW) interact with T cells expressing the TCR V beta 6, 7, 8.1, and 9 domains. Furthermore, the COOH termini of their ORF molecules, thought to confer TCR specificity, are very similar. Since successful transport of MMTV from the site of infection in the gut to the mammary gland depends on a functional immune system, we were interested in determining the early events after and requirements for MMTV infection. We show that MMTV(SW) infection induces a massive response of V beta 6+ CDC4+ T cells, which interact with the viral ORF. Concomitantly, we observed a B cell response and differentiation that depends on both the presence and stimulation of the superantigen-reactive T cells. Furthermore, we show that B cells are the main target of the initial MMTV infection as judged by the presence of the reverse-transcribed viral genome and ORF transcripts. Thus, we suggest that MMTV infection of B cells leads to ORF-mediated B-T cell interaction, which maintains and possibly amplifies viral infection.

Regional coronary endothelial function is closely related to local early coronary atherosclerosis in patients with mild coronary artery disease: pilot study.

BACKGROUND: Coronary endothelial function is abnormal in patients with established coronary artery disease and was recently shown by MRI to relate to the severity of luminal stenosis. Recent advances in MRI now allow the noninvasive assessment of both anatomic and functional (endothelial function) changes that previously required invasive studies. We tested the hypothesis that abnormal coronary endothelial function is related to measures of early atherosclerosis such as increased coronary wall thickness. METHODS AND RESULTS: Seventeen arteries in 14 healthy adults and 17 arteries in 14 patients with nonobstructive coronary artery disease were studied. To measure endothelial function, coronary MRI was performed before and during isometric handgrip exercise, an endothelial-dependent stressor, and changes in coronary cross-sectional area and flow were measured. Black blood imaging was performed to quantify coronary wall thickness and indices of arterial remodeling. The mean stress-induced change in cross-sectional area was significantly higher in healthy adults (13.5%±12.8%, mean±SD, n=17) than in those with mildly diseased arteries (-2.2%±6.8%, P<0.0001, n=17). Mean coronary wall thickness was lower in healthy subjects (0.9±0.2 mm) than in patients with coronary artery disease (1.4±0.3 mm, P<0.0001). In contrast to healthy subjects, stress-induced changes in cross-sectional area, a measure of coronary endothelial function, correlated inversely with coronary wall thickness in patients with coronary artery disease (r=-0.73, P=0.0008). CONCLUSIONS: There is an inverse relationship between coronary endothelial function and local coronary wall thickness in patients with coronary artery disease but not in healthy adults. These findings demonstrate that local endothelial-dependent functional changes are related to the extent of early anatomic atherosclerosis in mildly diseased arteries. This combined MRI approach enables the anatomic and functional investigation of early coronary disease.

Carotid artery stenting compared with endarterectomy in patients with symptomatic carotid stenosis (International Carotid Stenting Study): an interim analysis of a randomised controlled trial.

BACKGROUND: Stents are an alternative treatment to carotid endarterectomy for symptomatic carotid stenosis, but previous trials have not established equivalent safety and efficacy. We compared the safety of carotid artery stenting with that of carotid endarterectomy. METHODS: The International Carotid Stenting Study (ICSS) is a multicentre, international, randomised controlled trial with blinded adjudication of outcomes. Patients with recently symptomatic carotid artery stenosis were randomly assigned in a 1:1 ratio to receive carotid artery stenting or carotid endarterectomy. Randomisation was by telephone call or fax to a central computerised service and was stratified by centre with minimisation for sex, age, contralateral occlusion, and side of the randomised artery. Patients and investigators were not masked to treatment assignment. Patients were followed up by independent clinicians not directly involved in delivering the randomised treatment. The primary outcome measure of the trial is the 3-year rate of fatal or disabling stroke in any territory, which has not been analysed yet. The main outcome measure for the interim safety analysis was the 120-day rate of stroke, death, or procedural myocardial infarction. Analysis was by intention to treat (ITT). This study is registered, number ISRCTN25337470. FINDINGS: The trial enrolled 1713 patients (stenting group, n=855; endarterectomy group, n=858). Two patients in the stenting group and one in the endarterectomy group withdrew immediately after randomisation, and were not included in the ITT analysis. Between randomisation and 120 days, there were 34 (Kaplan-Meier estimate 4.0%) events of disabling stroke or death in the stenting group compared with 27 (3.2%) events in the endarterectomy group (hazard ratio [HR] 1.28, 95% CI 0.77-2.11). The incidence of stroke, death, or procedural myocardial infarction was 8.5% in the stenting group compared with 5.2% in the endarterectomy group (72 vs 44 events; HR 1.69, 1.16-2.45, p=0.006). Risks of any stroke (65 vs 35 events; HR 1.92, 1.27-2.89) and all-cause death (19 vs seven events; HR 2.76, 1.16-6.56) were higher in the stenting group than in the endarterectomy group. Three procedural myocardial infarctions were recorded in the stenting group, all of which were fatal, compared with four, all non-fatal, in the endarterectomy group. There was one event of cranial nerve palsy in the stenting group compared with 45 in the endarterectomy group. There were also fewer haematomas of any severity in the stenting group than in the endarterectomy group (31 vs 50 events; p=0.0197). INTERPRETATION: Completion of long-term follow-up is needed to establish the efficacy of carotid artery stenting compared with endarterectomy. In the meantime, carotid endarterectomy should remain the treatment of choice for patients suitable for surgery. FUNDING: Medical Research Council, the Stroke Association, Sanofi-Synthélabo, European Union.

Expression and presentation of endogenous mouse mammary tumor virus superantigens by thymic and splenic dendritic cells and B cells.

Tolerance against superantigens (SAgs) encoded by endogenous mouse mammary tumor virus (Mtv) loci involves the intrathymic deletion of SAg-reactive T cells expressing a particular TCR V beta-chain, presumably upon presentation of the SAg by specialized APC. However, although the role of dendritic cells (DC) in the induction of tolerance against conventional Ags has been demonstrated, little is known about the role played by DC in tolerance induction against Mtv SAgs. Moreover, there is conflicting evidence concerning the capacity of DC to express and present Mtv SAgs. In this report we have analyzed the expression of Mtv SAgs in highly purified thymic and splenic DC and B cells by reverse transcriptase-PCR, using primers amplifying Mtv SAg-specific spliced mRNAs. DC express Mtv SAgs at levels comparable to B cells, but display a differential expression pattern of the various Mtv loci compared with B cells. Furthermore, our results show that DC are able to induce the deletion of SAg-reactive thymocytes in an in vitro assay, indicating that Mtv SAgs are functionally expressed on the DC surface. Collectively, our data are consistent with the hypothesis that DC play a role in the induction of intrathymic tolerance to Mtv SAgs.

Intravenous thrombolysis in patients with stroke attributable to small artery occlusion.

BACKGROUND: Intravenous thrombolysis (IVT) for stroke seems to be beneficial independent of the underlying etiology. Recent observations raised concern that IVT might cause harm in patients with strokes attributable to small artery occlusion (SAO). OBJECTIVE: The safety of IVT in SAO-patients is addressed in this study. METHODS: We used the Swiss IVT databank to compare outcome and complications of IVT-treated SAO-patients with IVT-treated patients with other etiologies (non-SAO-patients). Main outcome and complication measures were independence (modified Rankin scale <or=2) at 3 months, intracranial hemorrhage (ICH), and recurrent ischaemic stroke. RESULTS: Sixty-five (6.2%) of 1048 IVT-treated patients had SAO. Amongst SAO-patients, 1.5% (1/65) patients died, compared to 11.2% (110/983) in the non-SAO-group (P = 0.014). SAO-patients reached independence more often than non-SAO-patients (75.4% versus 58.9%; OR 2.14 (95% CI 1.20-3.81; P = 0.001). This association became insignificant after adjustment for age, gender, and stroke severity (OR 1.41 95% CI 0.713-2.788; P = 0.32). Glucose level and (to some degree) stroke severity but not age predicted 3-month-independence in IVT-treated SAO-patients. ICHs (all/symptomatic) were similar in SAO- (12.3%/4.6%) and non-SAO-patients (13.4%/5.3%; P > 0.8). Fatal ICH occurred in 3.3% of the non-SAO-patients but none amongst SAO-patients. Ischaemic stroke within 3 months after IVT reoccurred in 1.5% of SAO-patients and in 2.3% of non-SAO-patients (P = 0.68). CONCLUSION: IVT-treated SAO-patients died less often and reached independence more often than IVT-treated non-SAO-patients. However, the variable 'SAO' was a dependent rather than an independent outcome predictor. The absence of an excess in ICH indicates that IVT seems not to be harmful in SAO-patients.

Contribution of major cardiovascular risk factors to familial premature coronary artery disease : the GENECARD project

Résumé Objectifs: Cette étude relève la prévalence des principaux facteurs de risque cardiovasculaire dans les coronaropathies précoces (P-CAD) familiales, survenant chez au moins deux frères et/ou soeurs d'une même fratrie. Méthodes: Nous avons recruté 213 survivants atteints de P-CAD, issus de 103 fratries, diagnostiqués avant l'âge de 50 ans chez les hommes et 55 ans chez les femmes. La présence ou non d'hypertension, d'hypercholestérolémie, d'obésité et de tabagisme a été documentée au moment de l'événement chez 163 de ces patients (145 hommes et 18 femmes). Chaque patient a été comparé à deux individus de même âge et sexe, chez qui un diagnostic de P-CAD «sporadique» (non familiale) était posé, et à trois individus choisis au hasard parmi la population générale. Résultats: En comparaison de la population générale, les patients atteints de P-CAD sporadique avaient une prévalence supérieure pour l 'hypertension (29% vs. 14%, p<0.001), le cholestérol (54% vs. 33%, p<0.001), l'obésité (20% vs. 13%, p<0.001) et le tabagisme (76% vs. 39%, p<0.001). Ces facteurs de risque étaient de prévalences similaires, voire supérieures chez les patients atteints de P-CAD familiale (43% [p0.05 vs. P-CAD sporadiques], 58% [p=0.07], 21% et 72% respectivement). Seulement 7 (4%) des 163 patients atteints de P-CAD familiale et 22 (7%) des 326 patients atteints de P-CAD sporadique, ne présentaient aucun facteur de risque cardiovasculaire, comparés à 167 (34%) des 489 patients issus de la population générale. Conclusions: Les facteurs de risque cardiovasculaire classiques et réversibles ont une haute prévalence chez les patients atteints de P-CAD familiale. Ce fait rend improbable une contribution génétique prédominante, agissant en l'absence de facteurs de risque. Summary Objectives: This study was designed to assess the prevalence of major cardiovascular risk factors in familial premature coronary artery disease (P-CAD), affecting two or more siblings within one sibship. Background: Premature CAD has a genetic component. It remains to be established whether familial P-CAD is due to genes acting independently from major cardiovascular risk factors. Methods: We recruited 213 P-CAD survivors from 103 sibships diagnosed before age ?50 (men) or ?55 (women) years old. Hypertension, hypercholesterolemia, obesity, and smoking were documented at the time of the event in 163 patients (145 men and 18 women). Each patient was compared with two individuals of the same age and gender, diagnosed with sporadic (nonfamilial) P-CAD, and three individuals randomly sampled from the general population. Result: Compared with the general population, patients with sporadic P-CAD had a higher prevalence of hypertension (29% vs. 14%, p < 0.001), hypercholesterolemia (54% vs. 33%, p < 0.001), obesity (20% vs. 13%, p < 0.01), and smoking (76% vs. 39%, p < 0.001). These risk factors were equally or even more prevalent in patients with familial P-CAD (43% [p < 0.05 vs. sporadic P-CAD], 58% [p = 0.07], 21% and 72%, respectively). Overall, only 7 (4%) of 163 of patients with familial P-CAD and 22 (7%) of 326 of patients with sporadic P-CAD had none of these conditions, as compared with 167 (34%) of 489 patients in the general population. Conclusions: Classic, remediable risk factors are highly prevalent in patients with familial P-CAD. Accordingly, a major contribution of genes acting in the absence of these risk factors is unlikely.