[en] The induction of mutations at the Hprt locus and minisatellite sequences was studied in V79 cells, peripheral blood lymphocytes (PBL) and lymphoblastoid cells (CCRF-CEM) exposed to gamma rays. In V79 cells the Hprt mutant frequency increased with dose at least up to 6.0 Gy, whereas the number of HPRT mutant lymphocytes increased up to 3 Gy. Clones derived from single irradiated cells were screened for mutations at minisatellite sequences by DNA fingerprint analysis. In V79 cells, a dose-response curve for minisatellite alterations was obtained up to 4.5 Gy. In contrast, very few mutations at minisatellite sequences (2/137) were detected among clones isolated from PBL of two donors irradiated with 1-4 Gy. Similar results were observed in lymphoblastoid CCRF-CEM cells irradiated with 2-3 Gy (4 mutants/180 clones), suggesting that in human lymphoid cells minisatellite DNA is more stable than in other mammalian and human cell lines. (author)
Journal
[en] Protons and a particles of high linear energy transfer (LET) have shown an increased relative biological effectiveness with respect to X/gamma rays for several cellular and molecular endpoints in different in vitro cell system. To contribute to understanding the biochemical mechanisms involved in the increased effectiveness of high LET radiation, an extensive study has been designed. The present work reports the preliminary result of this study on two human tumoural cell lines. DLD1 and HCT116, (with different p53 status), which indicate that for these cell lines, p53 does not appear to take a part in the response to radiation induced DNA damage, suggesting an alternative p53-independent pathway and a cell biochemical mechanism dependent on the cell type. (author)
Journal