Mitochondrial alterations in fanconi anemia fibroblasts following ultraviolet A or psoralen photoactivation.

The genetic disease Fanconi anemia (FA), generally considered to be a DNA repair defect, has also been related to a deficiency in cellular defense against reactive oxygen species (ROS). Results show that mitochondrial matrix densification occurs rapidly and transiently in FA fibroblasts following 8-methoxypsoralen (8-MOP) photoreaction or ultraviolet A (320 to 380 nm) (UVA) irradiation. This effect is oxygen dependent because it is more important under 20 than under 5% oxygen tension.

Activated ras oncogene and specifically acquired resistance to cisplatin in human mammary epithelial cells: induction of DNA cross-links and their repair.

A human non-malignant mammary epithelial cell line, HBL100, and the ras-transformed HBL100/ras1 cell line were examined for their sensitivity to cis-diamminedichloroplatinum(II) (cisplatin). The clonogenic cell survival assay showed that HBL100/ras1 exhibited a 2.7-fold increased resistance compared to the parental HBL100 cell line.

Studies on the influence of the presence of an activated ras oncogene on the in vitro radiosensitivity of human mammary epithelial cells.

The clonogenic cell survival to gamma-rays was determined in a human mammary epithelial cell line transfected by an activated ras oncogene in comparison to either the host untransfected cell line or the same cell line transfected by the neo gene. In contrast to previous observation of fibroblasts derived from a murine cellular system (NIH 3T3), the analysis of survival curves did not demonstrate an acquired radioresistance in the human ras transfected cells as opposed to the two other cell lines. In other words, the appearance of resistance to ionizing radiation does not seem to be a feature which can be generalized to all situations associated to activation of a specific oncogene (ras).

The cytostatic efficiency of gamma-rays on organotypic cultures of malignant cells is greater with irradiation at 23 degrees C compared to 37 degrees C.

The cytostatic efficiency of gamma-rays was determined following irradiation at 23 degrees C or 37 degrees C on A549 human lung carcinoma cells, irradiated either in monolayers or in three-dimensional organotypic cultures (nodules) with a dose-rate of 0.5 Gy/min. For the monolayers, the residual colony forming ability of single cells, and for the nodules, the growth rate, the proportion of regenerating or disaggregating nodules and the growth rate of regenerated nodules were measured.

Long term regeneration of cis-platinum and X ray treated human tumor nodules maintained in continuous organotypic culture.

A simple method for maintaining tumor cells in continuous three-dimensional culture, derived from Wolff's organotypic technique, has been used to study the effects of cis-platinum and X rays on growth inhibition, regrowth and long term regeneration of cultures maintained in low traumatizing conditions (absence of enzymatic dissociation of the cells and the possibility of avoiding subculturing, if necessary). The tumor nodules were derived from cells of the A 549 lung carcinoma cell line. The nodules developed an alveolar structure.