Comparative analysis of thymidylate synthase, thymidine phosphorylase and dihydropyrimidine dehydrogenase expression in colorectal cancer and surrounding normal tissue.

Thymidylate synthase [TS], thymidine phosphorylase [TP] and dihydropyrimidine dehydrogenase [DPD] play the essential role in the activation and catabolism of the fluoropyrimidines used in cancer therapy. Its expression may influence the antitumor activity or toxicity of these drugs. We studied the expression levels of selected enzymes in colorectal tumors and adjacent normal mucosa. The analysis of TS, TP and DPD gene expression was performed using quantitative Real time PCR technique (Roche) in 15 (TS), 64 (TP) and 12 (DPD) of 64 colorectal cancer patients. The mean gene expression of TS, TP and DPD was found to be 3.29; 3.79 and 8.24 in tumors and 1.88; 3.80 and 19.69 in normal mucosa. The corresponding median gene expression was 1.87; 2.32 and 4.50 for tumors and 2.14; 2.63 and 11.64 for normal tissue. We did not find any significant differences in TS, TP and DPD gene expression between colorectal tumor and surrounding mucosa.

[Cellular and tissue hypoxia--role of the von Hippel Lindau gene and hypoxia-inducible factor-1]. / Bunecná a tkánová hypoxie--úloha von Hippel Lindau genu a hypoxií indukovaného faktoru-1.

Hypoxia results in increased expression of some genes. This can compensate effects of hypoxia on the organism, and adapt cells and tissues to the environment with low oxygen tension. Mechanisms of cell and tissue responses to hypoxia have been extensively studied last years. The first identified mediator of cell response to hypoxia was hypoxia-inducible factor (HIF-1), which is being up regulated during hypoxic conditions. It binds to regulatory regions of sensitive genes and increases their transcription rate. Other key elements of cell response to hypoxia have been described recently--von Hippel-Lindau protein and prolyl hydroxylases, that allow degradation of alpha-subunit of HIF-1 during normal oxygen tension. This can ensure low level of HIF-1 in cells under physiological oxygen tension thus the expression of target genes is maintained on basal level. These new findings are starting points for further research and possible therapeutic use.

Cytokine gene expression in regenerating haematopoietic tissues of mice after cyclophosphamide treatment.

The goal of the study was to investigate changes in expression of selected growth factors tentatively involved in regeneration of haematopoietic tissues (bone marrow and spleen) following cyclophosphamide (CY) damage in the mouse. The bone marrow (BM) and spleen were examined separately, since the regenerating pattern for haematopoietic progenitor cells (HPC) markedly differs in these two haematopoietically active organs after CY. Cytokines assumed to have a stimulatory effect on HPC - stem cell factor (SCF), fetal liver tyrosine kinase 3-ligand (flt3-ligand), thrombopoietin (TPO), stromal cell-derived factor 1 (SDF-1), oncostatin M (OSM) -, a suppressive effect on HPC proliferation - macrophage inflammatory protein-1alpha (MIP-1alpha), transforming growth factor-beta1 (TGFbeta1), tumour necrosis factor-alpha (TNFalpha) - and to be involved in migration of HPC (SCF, flt3-ligand, MIP1alpha, SDF-1) were examined at the level of mRNA expression by means of real-time RT-PCR. The expression of a particular cytokine appears to be similar in both BM and spleen of untreated mice. CY administration changed the expression pattern of the studied genes in BM and spleen. In BM, the levels of mRNAs for SCF and SDF-1 were increased and that for TGFbeta1 decreased at time intervals at which HPC are known to proliferate intensively during BM regeneration. In contrast, stimulated proliferation of HPC in spleen was accompanied by increased expression of flt3-ligand and oncostatin M. Upon mobilization of HPC from BM into blood after CY, the expression of SCF, TPO, SDF-1 and TGFbeta1 tends to decrease in BM. Accumulation of HPC in spleen is accompanied by increased mRNA for flt3-ligand and OSM. Our findings demonstrate that different cytokines may be involved in the proliferation and mobilization/homing of HPC during recovery after CY damage in BM and spleen.