Sodium butyrate (BU) is a molecule that acts as a histone deacetylase inhibitor. As compared with its well-known antineoplastic/antiproliferative effects, little is known about BU action on vascular cell dynamics. An imbalance of proliferation and migration in pulmonary arterial smooth muscle cells (PASMCs) is essential in the onset and progression of pulmonary arterial hypertension (PAH), a disease that is characterized by vascular lung derangement and that frequently has an unfavorable outcome. Here, we show that, in PASMCs of PAH rats, BU counteracted plateletderived growth factor (PDGF)-induced Ki67 expression, and arrested the cell cycle, mainly at G 0 /G 1 . BU decreased proliferating cell nuclear antigen, c-Myc and cyclin D1 transcription and protein expression, while increasing p21 expression. BU reduced the transcription of PDGF receptor-b, and that of Ednra and Ednrb, two major receptors in PAH progression. Wound healing, migration and pulmonary artery ring assays indicated that BU inhibited PDGF-induced PASMC migration. BU strongly inhibited PDGFinduced Akt phosphorylation, an effect reversed by the phosphatase inhibitor calyculin A. BU-treated cells showed a remarkable increase in acetylated Akt, indicating an inverse relationship between the levels of acetylated Akt and phospho-Akt. These findings may provide novel perspectives on the use of histone deacetylase inhibitors in PAH.

No abstract

Li-Fraumeni syndrome (LFS) is a rare genetic cancer predisposition disease, partly determined by the presence of a TP53 germline mutation; lacking thereof, in presence of a typical LFS phenotype, defines a wide group of 'LFS Suggestive' patients. Alternative LFS susceptibility genes have been investigated without promising results, thus suggesting other genetic determinants involvement in cancer predisposition. Hence, this study explores the single and combined effects of cancer risk, age of onset and cancer type of three single nucleotide polymorphisms (SNPs)-TP53 Pro72Arg, MDM2 SNP285 and SNP309-already described as modifiers on TP53 mutation carriers but not properly investigated in LFS Suggestive patients. This case-control study examines 34 Italian LFS Suggestive lacking of germline TP53 mutations and 95 tumour-free subjects. A significant prevalence of homozygous MDM2 SNP309 G in the LFS Suggestive group (p < 0.0005) confirms its contribute to cancer susceptibility, also highlighted in LFS TP53 positive families. Conversely its anticipating role on tumour onset has not been confirmed, as in our results it was associated with the SNP309 T allele. A strong combined outcome with a 'dosage' effect has also been reported for TP53 P72 and MDM2 SNP309 G allele on cancer susceptibility (p < 0.0005). Whereas the MDM2 SNP285 C allele neutralizing effect on MDM2 SNP309 G variant is not evident in our population. Although it needs further evaluations, obtained results strengthen the role of MDM2 SNP309 as a genetic factor in hereditary predisposition to cancer, so improving LFS Suggestive patients management.

No abstract

IntroductionPulmonary arterial hypertension (PAH) is defined as a group of diseases caused by an increased pulmonary vascular resistance and subsequent right ventricular failure. This syndrome is characterized by abnormalities of pulmonary vascular biology in each compartment of the blood vessel. Vascular remodeling involves multiple signaling cascades regulating pulmonary arterial smooth muscle cells (PASMCs) proliferation, migration and differentiation. Sodium is a small butyrate histone deacetylase inhibitor affecting cell growth and differentiation. However, its effect on PASMCs had not been fully elucidated. Methods PASMCs were obtained from pulmonary artery of Wistar rats treated with a single dose of monocrotaline (MCT) in order to induce PAH. Cells were cultured in DMEM 10% FBS. PASMCs were starved in DMEM 0.5% FBS for 24 hours and treated with PDGF-BB 20ng/ml and Butyrate 5mM. Cell number was assessed indirectly by staining with dye crystal violet and proliferation was measured by uptake assay. For cell H3 thyimidine analysis, cells were stained with propidium iodide and analyzed by flow cytometry. We used a standard wound healing assay and a rat cycle pulmonary artery ring assay to evaluate cellular migration. Cells were collected for protein or RNA extraction and Western blot and Real Time PCR were performed. Cells cultured on glass coverslips were stained for assay. immunofluorescence Results Sodium butyrate significantly inhibited proliferation, DNA synthesis and migration of PDGF-BB-stimulated PASMC through inactivation of Akt without inducing cell death. Treatment with butyrate reduces the expression and the activation of PDGFR. At the same time butyrate induces cell-cycle arrest in the G(0)/G(1) phase associated with down-regulation of c-Myc, PCNA and cyclin D1, in addition to up-regulation of p21 and p15 at gene and protein level. We have also observed a down regulation of both and receptors for endothelin1, well-known target in PAH therapy. Conclusions Proliferation and migration of PASMCs is the hallmark of PAH, leading to hypertrophy of the medial smooth muscle layers in pre-capillary arterioles. Due to its proliferative and promigratory effects PDGF-BB gives a fundamental contribute to the development and progression of vascular remodeling in all types of pulmonary arterial hypertension. Butyrate has shown to be be effective in reducing PDGF-BB induced proliferation and migration in PASMCs. Moreover is able to reduce PASMCs responsiveness to endotelin1.