Hyperthermia inhibits cell proliferation and induces apoptosis: relative signaling status of P53, S100A4, and Notch in heat sensitive and resistant cell lines.

The effects of hyperthermia on the expression of p53, the apoptosis-associated genes Bax and Bcl-2, Notch and S100A4 have been studied in the HepG2 cell line and the HUT cell line derived from HepG2, adapted for growth in hyperthermic conditions. Hyperthermia inhibits cell proliferation and induces apoptosis. HepG2 and HUT cells differed in respect of anchorage to growth surface, degree of proliferation and apoptosis and expression of p53, Bax, Bcl-2, Notch, and S100A4 genes.

Stathmin in Cell Proliferation and Cancer Progression.

The phosphoprotein stathmin exerts profound influences on cell proliferation, differentiation and in cell motility. These phenotypic features are displayed in response to specific signals imparted to the cell by biological response modifiers. Stathmin functions as a focal point in co-ordinating and directing the cellular signals into specific and defined pathways.

Prediction of nodal spread of breast cancer by using artificial neural network-based analyses of S100A4, nm23 and steroid receptor expression.

The expression of tumour promoter gene S100A4, metastasis suppressor gene nm23, oestrogen and progesterone receptors, and tumour grade and size have been investigated for their potential to predict breast cancer progression. The molecular and cellular data have been analysed using artificial neural networks to determine the potential of these markers to predict the presence of metastatic tumour in the regional lymph nodes. This study shows that tumour grade and size are poor predictors.

Stathmin is involved in S100A4-mediated regulation of cell cycle progression.

S100A4 is a cell proliferation- and cancer metastasis-related gene. Previous studies have shown that over-expression of S100A4 drives the cells into the S-phase of the cell cycle, with concomitant enhancement of p53 detection. This has led to the postulate that S100A4 could be controlling cell cycle progression by sequestering p53 and abrogating its G1-S checkpoint control.

Synthesis of (E)-9-(1-pyrenyl)-4-hydroxynon-2-enal, a fluorescent probe of the (E)-4-hydroxynon-2-enal with retained biological properties.

(E)-9-(1-pyrenyl)-4-hydroxynon-2-enal (FHNE), a fluorescent probe of (E)-4-hydroxynon-2-enal (HNE) is synthesised in seven steps and in 35% overall yield, starting from commercially available 1-pyrencarboxyaldehyde. When incubated with cultured HeLa cells this fluorescent probe penetrates cells and particularly concentrates in the region surrounding the nucleus. As the parent compound, HNE it is able to induce the activation of heat shock factor (HSF) and is able to induce the binding of HSF to heat shock element (HSE).

Characterization of a splice variant of metastasis-associated h-mts1 (S100A4) gene expressed in human infiltrating carcinomas of the breast.

The h-mts1 (S100A4) is a member of the S100 gene family, coding for a calcium-binding protein. It is a metastasis-associated gene whose expression shows strong correlation with the proliferative potential and invasive and metastatic ability of cancers. In a proportion of human intraductal carcinomas of the breast, a shorter variant h-mts1 transcript (h-mts1v) of approximately 450 nucleotides is expressed.

Expression of metastasis-associated genes h-mts1 (S100A4) and nm23 in carcinoma of breast is related to disease progression.

The murine 18A2/mts1 and its human homolog h-mts1 (S100A4), encoding a Ca2+-binding protein belonging to the S-100 family, are associated with high invasive and metastatic potentials of murine tumors, human tumor cell lines in vitro, and human tumors growing as xenografts. The nm23 is a putative metastasis-suppressor gene whose expression has been found to correlate inversely with the metastatic potential of some forms of human cancer. The products of both human genes alter cytoskeletal dynamics, with antagonistic effects.

Heat shock modulates the expression of the metastasis associated gene MTS1 and proliferation of murine and human cancer cells.

Mts1 is a metastasis-associated gene of the S-100 gene family and codes for a Ca2+-binding protein. It is highly expressed in murine and human cancers of high invasive and metastatic potential. Recent work has shown that the mts1 protein might be involved in cell cycle regulation.

Structural requirements of aldehydes produced in LPO for the activation of the heat-shock genes in HeLa cells.

The ability of various aldehydes, some of which are produced in lipid peroxidation, to effect heat-shock gene expression and heat-shock proteins synthesis was evaluated in HeLa cells. Only (E)-4-hydroxyalk-2-enals were active both in racemic and homochiral form. Between the reported primary metabolic products of (E)-4-hydroxynon-2-enal, only the glutathione conjugates were active, whereas (E)-4-hydroxynon-2-enoic acid and 2-nonen-1,4-diol were inactive.

Metastasis-associated mts1 gene expression is down-regulated by heat shock in variant cell lines of the B16 murine melanoma.

Tumour cells are more heat sensitive than corresponding normal cells but the reasons for this are poorly understood. Here we report that induction of heat shock proteins was associated with a down-regulation of the metastasis associated mts1 gene in BL6-B16 murine melanoma cells, and the heat-resistant HTG variant of the BL6 line. Melanocyte stimulating hormone, which does not affect B16 cell proliferation but upregulates mts1 expression, only marginally enhanced heat shock protein expression in F1 cells as determined by immunohistochemical methods.

In vitro activation of heat shock transcription factor by 4-hydroxynonenal.

In the activation of eukaryotic heat shock genes, the acquisition of a binding ability to specific DNA sequence by a transcriptional activator, heat shock factor (HSF), is believed to be a crucial step. The induction of this new DNA binding activity of HSF is also obtained in a cell-free system (in vitro activation) by hyperthermia or at physiological temperature by calcium ions, low pH, urea, or non-ionic detergent. We report here the in vitro activation of HSF by treating at 0 degrees C a HeLa cell-free system with the aldehyde 4-hydroxynonenal (HNE), a highly cytotoxic product of lipid peroxidation.

4-Hydroxynonenal induces a DNA-binding protein similar to the heat-shock factor.

By using a gel mobility assay, we have shown that treatment of HeLa cells with 4-hydroxynonenal, a major product of the peroxidation of membrane lipids and an inducer of heat-shock proteins, has the same effect as heat shock in causing the appearance of a protein which binds to the sequence of DNA specific for the induction of heat-shock genes. Lipoperoxidation and heat exposure seem to share a common mechanism of specific gene activation.

The action of 4-hydroxynonenal on heat shock gene expression in cultured hepatoma cells.

Hep G2 cells do not synthesize heat-shock proteins when incubated with ADP-iron, under conditions that can trigger lipoperoxidation. However, exposure of these cells to added 4-hydroxynonenal (HNE), one of the main products of lipoperoxidation, induces the synthesis of hsp70, the most conserved among heat-shock proteins. HNE acts mainly on transcription: in Hep G2 cells the increase in the steady-state level of hsp70 mRNA is detectable by two different hybridization techniques.

C-myc gene expression in heat-adapted and heat-shocked cells.

The steady-state level of c-myc transcripts increases in cells exposed to high temperatures. Therefore c-myc can be included with c-fos in the family of heat-inducible oncogenes. Activation of c-myc upon heat exposure could in turn account for the induction of heat-shock proteins but recent observations suggest also alternative interpretations.

Oxidative stress induces a subset of heat shock proteins in rat hepatocytes and MH1C1 cells.

Lipoperoxidative damage caused by exposure of isolated hepatocytes or cultivated hepatoma cells to ADP-iron or to 4-hydroxynonenal induces the synthesis of some proteins which are different under these two conditions but are always a subset of the proteins induced in each type of cells upon heat-shock (heat-shock proteins). For at least one of these proteins (hsp 31), induced by 4-hydroxynonenal, the increase is dose-dependent and the effect of heat and the chemical seems to be additive. Lipoperoxidation may be implicated in the induction of some of the heat shock proteins, but reproduces only incompletely the response of protein synthesis typical of heat-shock conditions.

Synthesis of heat-shock proteins and tumor growth.

Exposure to hyperthermia induces the preferential synthesis of a set of proteins, known as heat-shock proteins. The synthesis of heat-shock proteins has been studied in rat liver cells, and human lymphocytes, and in their neoplastic counterparts. Tumor cells synthesize heat-shock proteins essentially as their normal controls, but the response of ascites hepatoma cells depends on the presence of glucose in the medium.

Soluble factors of protein synthesis in rat liver during the acute-phase reaction.

Cell sap of liver cells from rats undergoing an acute-phase reaction has an increased capacity for binding leucine to tRNA. This increased capacity does not depend on concurrent changes in the leucine pool. The kinetics of activity of leucyl-tRNA synthetase from acute-phase cell sap do not show relevant differences from the normal.

The role of nuclei, polyribosomes and cytosol factors in the onset of the acute-phase reaction in the liver cell.

Nuclei isolated from livers of turpentine-treated rats show an increased RNA synthesis, reaching a maximum at 10 h after treatment. The stimulation affects both alpha-amanitin-resistant and alpha-amanitin-sensitive activities, suggesting that pre-ribosomal and pre-messenger RNA formation are activated at the same time and to the same extent. The amount of ribosomal RNA, which is still normal 10 h after treatment, increases significantly at 24 h, but the increase is limited to the bound ribosomes, in keeping with the fact that the acute phase reactants are export proteins.

The effect of phenobarbital on protein metabolism of liver. Results with isolated hepatocytes.

A technique has been devised which makes use of an amino acid alternatively labeled with either [14C] or [3H], and permits the simultaneous evaluation of synthesis, catabolism and secretion by the same sample of isolated rat liver cells during the same time-period of incubation. This technique has been used to study protein metabolism of liver cells isolated from rats treated with 4 doses of phenobarbital (8 mg/100 g body weight) given in the 4 days before killing the animals. Total protein synthesis and secretion do not change in phenobarbital-treated rats; albumin represents 40% of secreted protein in both normal and treated rats.

Thioacetamide effects on protein metabolism in the liver: lessons from isolated hepatocytes.

The effects of a short-term treatment with thioacetamide have been studied in isolated hepatocytes obtained from intoxicated rats. A technique has been developed which utilizes leucine alternatively labeled with either [14C] or [3H] and permits the simultaneous evaluation of protein synthesis, catabolism and secretion in the same cell during the same incubation period. The results indicate that short-term thioacetamide treatment causes an overall slowing-down of protein metabolism.

Isoelectric characteristics and the secondary structure of some nucleic acids.

The isoelectric characteristics of some nucleic acid preparations from rat liver have been examined. 10S and 4S RNA species and SV-DNA were found to have isoelectric points of 5.2, 6.

Mechanisms of stimulation of protein synthesis in regenerating liver.

Cell sap obtained from regenerating liver is able to support an increased incorporation of [C] leucine into protein only when the rate of acylation of tRNA increases, as at 24 h after hepatectomy. When the rate of formation of amino acyl-tRNA returns to normal, as at 96 h after hepatectomy, the incorporation of amino acids into protein proceeds at a normal rate, in spite of persistent enhancement in amino acyl-tRNA incorporation into protein and in amino acyl-tRNA binding to ribosomes.