DNA methylation associated with polycomb repression in retinoic acid receptor ß silencing.

Retinoic acid receptor ß 2 (RARß2) is a tumor suppressor gene whose loss of expression is recurrent in prostate cancers. Here we studied the epigenetic mechanisms leading to its stable silencing. First, we characterized all RARß isoforms in 6 human tumor cell lines (prostate DU145, LNCaP, PC3, lung A549, breast Hs578T, and colon HCT116) by RT-PCR and Western blot. We excluded loss of heterozygosity (2D-FISH) and loss of RARa expression, an upstream regulator, as origin of RARß2 silencing. All data concluded to an epigenetic silencing. In agreement, a DNA methylation inhibitor restored its expression. Second RARß2 loss of expression was found associated with different epigenetic profiles in LNCaP and DU145 cells. According to bisulfite sequencing and ChIP analysis, we observed heavy methylation (97%) of the RARß2 promoter with repressive histone mark H3K9me3 in LNCaP. While DNA methylation and polycomb repression are described to be mutually exclusive at CpG-rich promoters, we observed that in DU145, moderate DNA methylation (36%) and H3K9me3 mark were present concomitantly with H3K27me3, a signature of polycomb repression. In summary, we provide new insights on how the RARß2 promoter is silenced, reveal the existence of two distinct repressive chromatin profiles at the same locus, and support a polycomb-mediated epigenetic repression process in prostate cancer.

Rapid synthesis of new DNMT inhibitors derivatives of procainamide.

DNA methyltransferases (DNMTs) are responsible for DNA methylation, an epigenetic modification involved in gene regulation. Families of conjugates of procainamide, an inhibitor of DNMT1, were conceived and produced by rapid synthetic pathways. Six compounds resulted in potent inhibitors of the murine catalytic Dnmt3A/3L complex and of human DNMT1, at least 50 times greater than that of the parent compounds. The inhibitors showed selectivity for C5 DNA methyltransferases. The cytotoxicity of the inhibitors was validated on two tumour cell lines (DU145 and HCT116) and correlated with the DNMT inhibitory potency. The inhibition potency of procainamide conjugated to phthalimide through alkyl linkers depended on the length of the linker; the dodecane linker was the best.

C5-DNA methyltransferase inhibitors: from screening to effects on zebrafish embryo development.

DNA methylation is involved in the regulation of gene expression and plays an important role in normal developmental processes and diseases, such as cancer. DNA methyltransferases are the enzymes responsible for DNA methylation on the position 5 of cytidine in a CpG context. In order to identify and characterize novel inhibitors of these enzymes, we developed a fluorescence-based throughput screening by using a short DNA duplex immobilized on 96-well plates. We have screened 114 flavones and flavanones for the inhibition of the murine catalytic Dnmt3a/3L complex and found 36 hits with IC(50) values in the lower micromolar and high nanomolar ranges. The assay, together with inhibition tests on two other methyltransferases, structure-activity relationships and docking studies, gave insights on the mechanism of inhibition. Finally, two derivatives effected zebrafish embryo development, and induced a global demethylation of the genome, at doses lower than the control drug, 5-azacytidine.

Paradoxical reactions to benzodiazepines in the elderly.

The prevalence of paradoxical reactions to benzodiazepines is estimated to be approximately 1% in the general population. The semiology can be very varied, diverse and misleading. Advanced age as well as cognitive disorders are classically described in the literature as risk factors for developing paradoxical reactions. However, this literature review only identified a limited number of articles focusing on the elderly and only one article on patients with neurocognitive disorders. This paradoxical situation raises questions as to whether these are unpublished clinical observations or whether the elderly population is really at risk, especially patients with neurocognitive disorders. Semiology can be confused with underlying neurocognitive disorders. Paradoxical reactions are ultimately only rarely or not evoked, leading to a very high risk of iatrogeny. It is therefore important to be aware of these paradoxical effects in order to be able to evoke them rapidly. The most striking semiological element would be the suddenness of onset of self-aggressive or hetero-aggressive behaviours.

[Paradoxical reactions to benzodiazepines in the elderly]. / Réactions paradoxales aux benzodiazépines chez la personne âgée.

The prevalence of paradoxical reactions to benzodiazepines is estimated of about 1% in the general population. The semiology can be very rich, diverse and misleading. Advanced age as well as cognitive disorders are classically described in the literature as risk factors for developing paradoxical reactions. However, the review of the literature has only identified a limited number of articles focusing on the elderly and only one article for patients with neurocognitive disorders. One may wonder about this paradox and whether these are unpublished clinical observations, or whether the elderly population is really at risk, especially patients with neurocognitive disorders. Semiology can be confused with underlying neurocognitive disorders. So, paradoxical reactions are ultimately only rarely or not evoked leading to a very high risk of iatrogeny. It is therefore important to be aware of these paradoxical effects in order to be able to evoke them quickly. The most striking semiological element would be the suddenness of onset of self-aggressive or hetero-aggressive behaviors.

Middle-term mortality and re-bleeding after initial diverticular bleeding: A nationwide study of 365 mostly elderly French patients.

BACKGROUND AND AIMS: The aim of this study was to determine the mortality and re-bleeding rates, and the risk factors involved, in a cohort of patients with previous diverticular bleeding (DB). METHODS: In 2007, data on 2462 patients with lower gastrointestinal (GI) bleeding were collected prospectively at several French hospitals. We studied the follow-up of patients with DB retrospectively. The following data were collected: age, mortality rates and re-bleeding rates, drug intake, surgery and comorbidities. RESULTS: Data on 365 patients, including 181 women (mean age 83.6 ± 9.8 years) were available. The median follow-up time was 3.9 years (IQR 25-75: 1.7-5.4). Of these, 148 patients died (40.5%). Among the 70 patients (19.2%) who had at least one re-bleeding episode, nine died and three underwent surgical procedures. Anticoagulation and antiplatelet therapy was discontinued in 70 cases (19.2%). The independent risk factors contributing to mortality were age > 80 years (HR = 3.18 (2.1-4.9); p < 0.001) and a Charlson comorbidity score > 2 (1.91 (1.31-2.79); p = 0.003). Discontinuation of therapy was not significantly associated with a risk of death due to cardiovascular events. No risk factors responsible for re-bleeding were identified, such as antiplatelet and anticoagulant therapy in particular. CONCLUSIONS: In this cohort, the rates of mortality and DB re-bleeding after a median follow-up time of 3.9 years were 19.2% and 40.5%, respectively. The majority of the deaths recorded were not due to re-bleeding.

Synthesis and evaluation of analogues of N-phthaloyl-l-tryptophan (RG108) as inhibitors of DNA methyltransferase 1.

DNA methyltransferases (DNMT) are promising drug targets in cancer provided that new, more specific, and chemically stable inhibitors are discovered. Among the non-nucleoside DNMT inhibitors, N-phthaloyl-l-tryptophan 1 (RG108) was first identified as inhibitor of DNMT1. Here, 1 analogues were synthesized to understand its interaction with DNMT. The indole, carboxylate, and phthalimide moieties were modified. Homologated and conformationally constrained analogues were prepared. The latter were synthesized from prolinohomotryptophan derivatives through a methodology based amino-zinc-ene-enolate cyclization. All compounds were tested for their ability to inhibit DNMT1 in vitro. Among them, constrained compounds 16-18 and NPys derivatives 10-11 were found to be at least 10-fold more potent than the reference compound. The cytotoxicity on the tumor DU145 cell line of the most potent inhibitors was correlated to their inhibitory potency. Finally, docking studies were conducted in order to understand their binding mode. This study provides insights for the design of the next-generation of DNMT inhibitors.

Therapeutic education in coronary heart disease: position paper from the Working Group of Exercise Rehabilitation and Sport (GERS) and the Therapeutic Education Commission of the French Society of Cardiology.

Cardiovascular mortality has decreased over the past 25 years, largely because of acute coronary syndrome care and preventive actions. Nevertheless, the rate of coronary heart disease remains high, with an annual risk of 4.7% (cardiac mortality, myocardial infarction, stroke). Cardiovascular risk factor management must be a priority in primary and secondary prevention, to improve the prognosis of this severe disease, in which absence of symptoms does not mean benignity. The current goals of therapeutic patient education are smoking cessation, regular physical activity, a cardioprotective (Mediterranean) diet, management of stress, good treatment adherence (which improves compliance), judicious use of the care system and help with occupational reintegration. Current and future programmes must be in accordance with the Haute Autorité de Santé recommendations published in 2007.

[Palliative care in cardiology]. / Les soins palliatifs en cardiologie.

Palliative care is a subject which is not often broached in cardiology. Its development comes up against several difficulties. It is intended for patients suffering from heart failure and requires efficient and coherent communication between all the caregivers, the patient and his close relatives, in line with the principle of good treatment.

Mechanistic insights on the inhibition of c5 DNA methyltransferases by zebularine.

In mammals DNA methylation occurs at position 5 of cytosine in a CpG context and regulates gene expression. It plays an important role in diseases and inhibitors of DNA methyltransferases (DNMTs)--the enzymes responsible for DNA methylation--are used in clinics for cancer therapy. The most potent inhibitors are 5-azacytidine and 5-azadeoxycytidine. Zebularine (1-(beta-D-ribofuranosyl)-2(1H)- pyrimidinone) is another cytidine analog described as a potent inhibitor that acts by forming a covalent complex with DNMT when incorporated into DNA. Here we bring additional experiments to explain its mechanism of action. First, we observe an increase in the DNA binding when zebularine is incorporated into the DNA, compared to deoxycytidine and 5-fluorodeoxycytidine, together with a strong decrease in the dissociation rate. Second, we show by denaturing gel analysis that the intermediate covalent complex between the enzyme and the DNA is reversible, differing thus from 5-fluorodeoxycytidine. Third, no methylation reaction occurs when zebularine is present in the DNA. We confirm that zebularine exerts its demethylation activity by stabilizing the binding of DNMTs to DNA, hindering the methylation and decreasing the dissociation, thereby trapping the enzyme and preventing turnover even at other sites.