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Postconfluent cultures of HT-29 cells form a heterogeneous multilayer of which greater than 95% of the cells are undifferentiated. In contrast, when stably adapted to normally lethal concentrations of methotrexate (10(-6)-10(-5) M), they form a monolayer of gobletlike cells (Lesuffleur et al., 1990) which secrete large quantities of mucins and display a(More)
The HT-29 cell line contains a small proportion of differentiated polarized, enterocytic and mucus-secreting cell types (less than 95%) which can be selected under various pressure conditions, e.g., glucose deprivation or methotrexate. The purpose of the present work was to investigate whether this also applies to 5-fluorouracil (FUra). Stepwise adaptation(More)
PURPOSE To investigate changes in nucleotide metabolism after irradiation. MATERIALS AND METHODS HT29 and SW48 human colon carcinoma cells were exposed to 60Co gamma-rays at doses ranging from 0 to 7.5 Gy. At different times after irradiation, the activities of nine enzymes involved in nucleotide metabolism were measured, the levels of thymidine kinase(More)
The anti-oxidant metabolism was studied at different times after sub-culture in 2 colon cell lines previously characterized for their growth and differentiation properties. The HT29 cell line is mainly composed of proliferative and undifferentiative cells, while the derived 5-fluorouracil (FUra)-adapted cells undergo growth-dependent differentiation, which(More)
The activities of 5 enzymes involved in the pyrimidine metabolism were measured in xenografts of 8 human colon adenocarcinomas and in the corresponding primary tumors and normal tissues. The enzymes studied were thymidine kinase, thymidine phosphorylase, uridine kinase, uridine phosphorylase and thymidylate synthase. With the exception of the phosphorylases(More)
Cytogenetic studies performed on human colorectal tumors have revealed 2 specific patterns of chromosomal anomalies. The major pattern, known as the monosomic type (MT), is characterized by the loss or deletion of chromosomes 18, 17 (short arm 17p) and, less frequently, 1p, 4, 15, 5 (long arm 5q) and 21. The other one, known as the trisomic type (TT), is(More)
Karyotype, mitochondrial ultrastructure and several enzymatic activities were studied in two clones, D22 and D27, from SV40-transformed rabbit chondrocytes. Similar chromosome alterations, with recurrent losses and gains were observed at the various passages. Mitochondria were rare, with increase in size and crest alterations. By comparison to(More)
PURPOSE To establish and characterize an in vitro model of radiation-induced transformation of normal glial cells. MATERIALS AND METHODS During the last week of gestation, pregnant Sprague-Dawley rats were either irradiated at 3.5 Gy (0.022 Gy h(-1)) with a 60Co source or sham irradiated. On day 21 of gestation, cortical nerve cells from foetuses were(More)
Genistein, an isoflavonoid derivative initially described as an in vitro protein tyrosine kinase inhibitor, also inhibits mammalian DNA topoisomerase II both in vitro and in vivo. From a human leukaemic T cell line (CCRF-CEM), two genistein-resistant cell lines, which grow in the presence of 50 and 150 microM genistein, respectively, were selected and(More)
The inducibility of pulmonary microsomal enzymes and the biological effects of chronic induction by 5-6 benzoflavone and methylcholanthrene were compared in normal and precancerous rats. Two important points were shown out: a dose of 6000 WLM resulted in a permanent modification of the pulmonary microsomal enzymatic pool and 5-6 benzoflavon was a strong(More)