title: Response of radiation-sensitive human cells to defined DNA breaks.
abstract: We have investigated the response of four human cell lines, representing a range of sensitivities to ionizing radiation, to enzymes which induce defined DNA double-strand breaks (dsbs). Cell lines were derived from a normal individual, from the cancer-prone disorders ataxia-telangiectasia (AT) and Bloom's syndrome (BS), and from an immunodeficient individual (46BR). The molecular defects in AT and BS are unknown, while 46BR is known to be DNA ligase I deficient. We assayed the clonogenic survival of the cell lines following in vivo scission of the DNA by the restriction endonucleases PvuII and BanI. These two enzymes differ in their action; PvuII gives rise to dsbs with blunt termini, while BanI generates staggered ends with a 4 bp overhang. We found a correlation between the sensitivity of the cell lines to X-rays and to the blunt-end cutter PvuII, but not to the cohesive-end cutter BanI.
authors.affiliation: DNA Repair and Mutagenesis Group, MRC Radiobiology Unit, Chilton, UK.
authors.forename: N D
authors.initials: ND
authors.lastname: Costa
authors.forename: J
authors.initials: J
authors.lastname: Thacker
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000235:genetics* / Q000473:pathology; D001260:Ataxia Telangiectasia / Q000235:genetics* / Q000473:pathology; D001816:Bloom Syndrome / Q000235:genetics* / Q000473:pathology; D002460:Cell Line; D004249:DNA Damage; D004262:DNA Restriction Enzymes; D006801:Humans; D066298:In Vitro Techniques; D011836:Radiation Tolerance / Q000235:genetics*
chemical_list: D004262:DNA Restriction Enzymes