Impact of R264C and R264H polymorphisms in human aromatase function.

The cytochrome P450 aromatase is involved in the last step of sex hormones biosynthesis by converting androgens into estrogens. The human enzyme is highly polymorphic and literature data correlate aromatase single nucleotide polymorphisms to the onset of pathologies such as breast cancer and neurodegenerative diseases. The aims of this study were i) to study the influence of the mutations R264C and R264H on the structure-function of the enzyme also upon phosphorylation by selected kinases and ii) to compare the activity of the variants to that of aromatase wild type in two different cell lines.

Evidence for an elevated aspartate pK(a) in the active site of human aromatase.

Aromatase (CYP19A1), the enzyme that converts androgens to estrogens, is of significant mechanistic and therapeutic interest. Crystal structures and computational studies of this enzyme shed light on the critical role of Asp(309) in substrate binding and catalysis. These studies predicted an elevated pK(a) for Asp(309) and proposed that protonation of this residue was required for function.

Deoxyhypusine synthase (DHPS) inhibitor GC7 induces p21/Rb-mediated inhibition of tumor cell growth and DHPS expression correlates with poor prognosis in neuroblastoma patients.

Purpose: Neuroblastoma (NB) is an aggressive pediatric malignancy that typically occurs in infants and children under the age of 5 years. High-stage tumors relapse frequently even after aggressive multimodal treatment, resulting in therapy resistance and eventually in patient death. Clearly, new biologically-targeted drugs are needed that more efficiently suppress tumor growth and prevent relapse.

The pan-histone deacetylase inhibitor LBH589 (panobinostat) alters the invasive breast cancer cell phenotype.

Triple-negative breast cancer (TNBC) is a very aggressive type of tumour and its aggressiveness is linked to E-cadherin downregulation. In estrogen-sensitive breast cancer, high levels of E-cadherin fit with high levels of ERα and MTA3 (a component of the transcription Mi-2/NuRD complex with intrinsic DAC activity). In TNBC the E-cadherin downregulation could be due to epigenetic silencing of the CDH1 gene as well as to the lack of a fully functioning ERα-activated pathway.

Histone deacetylase inhibition modulates E-cadherin expression and suppresses migration and invasion of anaplastic thyroid cancer cells.

Context: Anaplastic thyroid cancer cells are characterized by a mesenchymal phenotype, as revealed by spindle-shaped cells and absent or reduced levels of E-cadherin. Epigenetic silencing is considered one of the leading mechanisms of E-cadherin impairment, which causes the acquisition of the invasive and metastatic phenotype of anaplastic thyroid cancer.

Objectives: In this study we investigated the effects of histone deacetylase inhibition on E-cadherin expression, cell motility, and invasion in anaplastic thyroid cancer cell cultures.

The biphasic nature of hypoxia-induced directional migration of activated human hepatic stellate cells.

Liver fibrogenesis is sustained by pro-fibrogenic myofibroblast-like cells (MFs), mainly originating from activated hepatic stellate cells (HSC/MFs) or portal (myo)fibroblasts, and is favoured by hypoxia-dependent angiogenesis. Human HSC/MFs were reported to express vascular-endothelial growth factor (VEGF) and VEGF-receptor type 2 and to migrate under hypoxic conditions. This study was designed to investigate early and delayed signalling mechanisms involved in hypoxia-induced migration of human HSC/MFs.

Chronic exposure to agmatine results in the selection of agmatine-resistant hepatoma cells.

During our study of the cytostatic effect of agmatine, we were able to isolate an agmatine resistant clone from a parental hepatoma cell line, HTC. These cells, called Agres, had slower growth rate than the parental cells when cultured in normal medium. The modification in polyamine content induced by agmatine was much lower in these cells and ornithine decarboxylase, S-adenosylmethionine decarboxylase and spermidine/spermine acetyltransferase activities were much less affected.

Polyamines modulate epithelial-to-mesenchymal transition.

Epithelial-to-mesenchymal transition and mesenchymal-to-epithelial transition are biologic processes responsible for conversion of epithelial cells into a mesenchymal phenotype or viceversa, respectively. They occur during embryo- and foetal-development and, in adult organisms, are involved in wound healing, in the genesis and progression of organ fibrosis as well as in the invasiveness of epithelial cancer cells. The key event of epithelial-to-mesenchymal transition is the loss of E-cadherin expression due to repressor activity of the transcriptional factor Snai1.

Dissection of the biphasic nature of hypoxia-induced motogenic action in bone marrow-derived human mesenchymal stem cells.

Hypoxic conditions have been reported to facilitate preservation of undifferentiated mesenchymal stem cell (MSC) phenotype and positively affect their colony-forming potential, proliferation, and migration/mobilization. In this study, designed to dissect mechanisms underlying hypoxia-dependent migration of bone marrow-derived human MSC (hMSC), signal transduction, and molecular mechanisms were evaluated by integrating morphological, molecular, and cell biology techniques, including the wound healing assay (WHA) and modified Boyden's chamber assay (BCA) to monitor migration. Exposure of hMSCs to moderate hypoxia resulted in a significant increase of migration of hMSCs in both WHA (from 6 to 20 hours) and BCA (within 6 hours).

Cytotoxic activity of the histone deacetylase inhibitor panobinostat (LBH589) in anaplastic thyroid cancer in vitro and in vivo.

Anaplastic thyroid carcinoma (ATC) has a rapidly fatal clinical course, being resistant to multimodal treatments. Microtubules, α/β tubulin heterodimers, are crucial in cell signaling, division and mitosis and are among the most successful targets for anticancer therapy. Panobinostat (LBH589) is a potent deacetylase inhibitor acting both on histones and nonhistonic proteins, including α-tubulin.

Endocellular polyamine availability modulates epithelial-to-mesenchymal transition and unfolded protein response in MDCK cells.

Epithelial-to-mesenchymal transition (EMT) is involved in embryonic development as well as in several pathological conditions. Literature indicates that polyamine availability may affect transcription of c-myc, matrix metalloproteinase (MMP)1, MMP2, TGFbeta(1), and collagen type I mRNA. The aim of this study was to elucidate polyamines role in EMT in vitro.

Redox mechanisms switch on hypoxia-dependent epithelial-mesenchymal transition in cancer cells.

Epithelial-mesenchymal transition (EMT) and hypoxia are considered as crucial events favouring invasion and metastasis of many cancer cells. In this study, different human neoplastic cell lines of epithelial origin were exposed to hypoxic conditions in order to investigate whether hypoxia per se may trigger EMT programme as well as to mechanistically elucidate signal transduction mechanisms involved. The following human cancer cell lines were used: HepG2 (from human hepatoblastoma), PANC-1 (from pancreatic carcinoma), HT-29 (from colon carcinoma) and MCF-7 (from breast carcinoma).

Cobalt induces oxidative stress in isolated liver mitochondria responsible for permeability transition and intrinsic apoptosis in hepatocyte primary cultures.

It is well established that cobalt mediates the occurrence of oxidative stress which contributes to cell toxicity and death. However, the mechanisms of these effects are not fully understood. This investigation aimed at establishing if cobalt acts as an inducer of mitochondrial-mediated apoptosis and at clarifying the mechanism of this process.

Beta-catenin triggers nuclear factor kappaB-dependent up-regulation of hepatocyte inducible nitric oxide synthase.

Disruption of cell-to-cell contacts, as observed in many pathophysiological conditions, prime hepatocytes for compensatory hyperplastic response that involves induction of several genes, including proto-oncogenes and other gene targets of beta-catenin signaling pathway. By using cultured hepatocytes and experimental models of adherens junction disruption we have investigated changes in beta-catenin subcellular localization and their relationships with inducible nitric oxide synthase (iNOS) expression. Two experimental models were employed: (a) rat hepatocytes obtained by collagenase liver perfusion within the first 48 h of culture; (b) 48-h old cultured hepatocytes, transiently transfected or not with a plasmid encoding for dominant/negative inhibitory kappa B-alpha, exposed to ethylene glycol-bis-(2-aminoethylether)-N,N,N',N'-tetraacetic acid/LiCl treatment.