Regulation of transcription of the glutathione S-transferase P1 gene by methylation of the minimal promoter in human leukemia cells.

To study the relationship between methylation and the transcriptional activity of the minimal promoter of the glutathione S-transferase GSTP1 gene encoding glutathione S-transferase P1-1, GSTP1 mRNA levels as well as basal promoter activity were compared in human leukemia cell lines. The K562 erythroleukemia cell line presented a strong GSTP1 promoter activity, as measured in transient transfection assays using a luciferase reporter plasmid, and correlated with a high mRNA whereas in Raji cells no mRNA was expressed. In order to establish a relationship between the expression and the methylation status, we used in vitro bisulfite sequencing which indicated that both methylated and unmethylated GSTP1 promoter alleles coexisted in K562 cells, whereas Raji lymphoma cells showed a nearly uniform hypermethylation of the promoter region. To determine the impact of methylation, we used in vitro SssI methylation of the minimal GSTP1 promoter, which led to the silencing of the promoter activity in transient transfection assays in expressing K562 as well as in non-expressing Raji cells. These data are in good agreement with previously obtained results and indicate that methylation of CpG sites of the basal promoter is an essential mechanism in the control of GSTP1 gene expression in human leukemia.

Phorbol ester responsiveness of the glutathione S-transferase P1 gene promoter involves an inducible c-jun binding in human K562 leukemia cells.

Overexpression of the glutathione S-transferase P1 (GSTP1) gene is related to drug resistance in human cancer cells. However, the mechanisms of the transcriptional activation of this gene remain unclear. In this study, we examined the molecular mechanisms underlying phorbol ester mediated gene regulation using human K562 leukemia cells as a model. Promoter deletion analyses revealed that the activator protein-1 (AP-1) transcription factor site was crucial for 12-O-tetradecanoyl phorbol 13-acetate (TPA)-mediated GSTP1 gene transcription. Electrophoretic mobility shift assays and transient transfection analysis demonstrated that both DNA binding and transactivation activities of AP-1 were induced by TPA. By supershift analysis, we identified transcription factors c-jun and fra-1 as well as NF-E2p45 as components of the induced binding complex. These results show for the first time that the phorbol ester TPA is involved in the molecular mechanism(s) mediating the activation of the GSTP1 promoter in a human leukemia model.

GTP-mediated differentiation of the human K562 cell line: transient overexpression of GATA-1 and stabilization of the gamma-globin mRNA.

Induction of specific gene expression may provide an alternative or a support to conventional cytotoxic chemotherapy of cancer, as well as to therapy for sickle cell diseases. In this respect, pharmacological induction of expression of the endogenous gamma-globin gene is a realistic approach to therapy of beta-globin disorders. Erythroid differentiation and inhibition of proliferation of the human CML K562 cell line was induced by guanosine 5'-triphosphate (GTP). The hemoglobin production in cells was correlated to an increase in alpha- and gamma-globin mRNA expression. At the transcriptional level, we showed that both the expression of the major erythroid transcription factor GATA-1 (protein and mRNA) and its binding capacity to the gamma-globin gene promoter was transiently increased. Moreover, GTP moderately stimulated the gamma-globin gene promoter after 48 h of treatment. At the post-transcriptional level, GTP treatment led to a drastic increase of the gamma-globin mRNA half-life. This stabilizing effect of GTP was mediated via the 3'-untranslated region (3'-UTR) of the gamma-globin mRNA. In conclusion, mechanism of GTP-mediated differentiation of K562 cells is linked to an early activation of gamma-globin gene transcription followed by a stabilization of its mRNA.

Jugular pulse and flow velocity anomalies: a diagnostic clue to an obstructive tricuspid prosthetic dysfunction.

Report of a case of obstructive dysfunction of a tricuspid Starr-Edwards (6120) ball prosthesis, diagnosed on phonocardiographic (PCG) diastolic anomalies with abnormal diastolic pattern of the jugular pulse, abnormal jugular flow velocity curve, and confirmed by cinefluoroscopy. The thrombotic origin of the obstruction was assessed on the regression of PCG and cinefluoroscopic anomalies under fibrinolytic therapy.

[Are nitrate compounds effective when administered orally? Results of pharmacokinetic and hemodynamic studies]. / Les dérivés nitrés sont-ils efficaces par la voie orale? Apport des données métaboliques at hémodynamiques.

Several reports had concluded that nitrates were not efficacious when administered by the oral route, on the basis of experiments which had shown a rapid denitration by the liver enzyme glutathion-organic nitrate reductase. Recent data demonstrate the efficacy of nitrates on parameters measured at cardiac catheterisation and echocardiography on condition that adequate doses are used. Doses commonly used up to now are often inadequate. The demonstration in the blood, after oral administration of adequate doses, of concentration of non-metabolized nitrates which are of the same order as those obtained after sublingual administration of clinically efficacious doses, confirms the efficacy of nitrates administered by the oral route.

[Ascending aortic aneurysm with mucoid infiltration of the media and aortic leaflets. Pathogenic hypotheses- surgical consequences]. / Les anévrysmes de l'aorte ascendante avec infiltration mucoïde de la média et des sigmoïdes. Hypothèses pathogéniques - conséquences chirurgicales.

The theoretical and practical problems posed by aneurysms of the ascending aorta with mucoid infiltration of the Media and the aortic leaflets are discussed with reference to two suggestive cases. These histological changes are not specific for Marfan's syndrome, the relation with which is very inconstant. Incomplete replacement of the affected tissues risks a recurrence which is especially serious when the sinus of Valsalva is involved. Therefore, total replacement of the ascending aorta with aortic valve replacement and reimplantation of the coronary arteries is generally indicated. Histology of the excised tissues should be performed routinely with specific stains for mucopolysaccharides. Close follow-up of operated patients with this condition is recommended, especially those with only partial replacements.

[Nitroglycerin infusion in patients with or without cardiac failure. Demonstration by multifactorial analysis (analysis of correspondences) of three types of hemodynamic response dependent upon the initial state (author's transl)]. / La trinitrine intraveineuse chez les malades avec et sans insuffisance cardiaque. Mise en évidence par une analyse multifactorielle (analyse des correspondances) de 3 types de réponse hémodynamique dépendant de l'état initial.

The effects of nitroglycerin on systemic vascular resistance and cardiac output are highly debated. This study demonstrates that these effects depend on the initial haemodynamic condition, and explains the conflicting results previously reported. 31 patients presenting initially with a fairly wide spectrum of various haemodynamic parameters underwent cardiac catheterisation with measures of parameters before and after nitroglycerin infusion. Multifactorial statistical analysis by correspondence analysis identifies 3 types of haemodynamic responses and demonstrates the association of each response with a particular haemodynamic profile. It is demonstrated that systemic vascular resistance is decreased only when it is initially elevated and cardiac output is increased only when initial pulmonary wedge pressure and systemic vascular resistance are elevated and cardiac output is low. The effects of nitroglycerin on cardiac output, systemic vascular resistance, heart rate and arterial pressure differ significantly according to the presence or not of cardiac insufficiency and depend mainly on the initial value of three parameters: systemic vascular resistance, pulmonary wedge pressure and cardiac output.