TY - JOUR
T1 - Chinese hamster ovary cells deficient or proficient in O6-alkylguanine-DNA alkyltransferase activity are equally sensitive to X-rays
AU - Pardini, C.
AU - Piras, A.
AU - Voliani, M.
AU - Rainaldi, G.
AU - Mariani, L.
AU - Taverna, P.
AU - D'Incalci, M.
AU - Citti, L.
PY - 1992
Y1 - 1992
N2 - In mammalian cells, under aerobic conditions, ionizing radiations and radiomimetic chemical agents can induce an enzymatic activity involved in DNA repair, O6-alkylguanine-DNA alkyltransferase (O6-AT). This catalytic protein is active against alkyl-radical-induced DNA damages. This induction was proposed to be linked to the formation of hydroxyl radicals. The possible involvement of O6-AT in the defense mechanism of the cell against aerobic radiation damage was investigated by comparing the X-ray sensitivity of two Chinese hamster ovary (CHO) cell lines, the first deficient (CHO mex-) and the second proficient by transfection of O6-AT (CHO mex+). The colony-forming ability after X-irradiation was appreciably reduced in CHO mex- in comparison to CHO mex+ cells. Nevertheless, pretreatment of proficient cells with O6-methylguanine, a specific inhibitor of O6-AT, reduced the DNA repair activity but did not modify the degree of sensitivity to X-rays of the CHO mex+ cells. Since the glutathione concentrations as well as the DNA damage amounts induced by X-irradiation were comparable in the variously treated cell lines, these results suggest that the observed induction of O6-AT by ionizing radiation in aerobic conditions could be a generalized rather than a specific response to damage by radicals.
AB - In mammalian cells, under aerobic conditions, ionizing radiations and radiomimetic chemical agents can induce an enzymatic activity involved in DNA repair, O6-alkylguanine-DNA alkyltransferase (O6-AT). This catalytic protein is active against alkyl-radical-induced DNA damages. This induction was proposed to be linked to the formation of hydroxyl radicals. The possible involvement of O6-AT in the defense mechanism of the cell against aerobic radiation damage was investigated by comparing the X-ray sensitivity of two Chinese hamster ovary (CHO) cell lines, the first deficient (CHO mex-) and the second proficient by transfection of O6-AT (CHO mex+). The colony-forming ability after X-irradiation was appreciably reduced in CHO mex- in comparison to CHO mex+ cells. Nevertheless, pretreatment of proficient cells with O6-methylguanine, a specific inhibitor of O6-AT, reduced the DNA repair activity but did not modify the degree of sensitivity to X-rays of the CHO mex+ cells. Since the glutathione concentrations as well as the DNA damage amounts induced by X-irradiation were comparable in the variously treated cell lines, these results suggest that the observed induction of O6-AT by ionizing radiation in aerobic conditions could be a generalized rather than a specific response to damage by radicals.
KW - CHO cells
KW - O-Alkylguanine-DNA alkyltransferase
KW - x-Ray sensivity
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U2 - 10.1016/0165-7992(92)90144-7
DO - 10.1016/0165-7992(92)90144-7
M3 - Article
C2 - 1381489
AN - SCOPUS:0026701589
VL - 283
SP - 125
EP - 129
JO - Mutation Research Letters
JF - Mutation Research Letters
SN - 0165-7992
IS - 2
ER -