The effects of radon daughter alpha-particle irradiation in K1 and xrs-5 CHO cell lines.
We investigated the radiobiological effects of the radon daughter bismuth-212 (212Bi) in Chinese hamster ovary (CHO) K1 cells and in xrs-5 cells, which are X-ray sensitive and deficient in the ability to rejoin DNA double-strand breaks. The cells were exposed to 250 kVp X-rays or to 212Bi chelated to diethylene triamine pentaacetic acid (DTPA); chelation of 212Bi to DTPA prevented its attachment to or entry into the cells. Cytotoxic, clastogenic, and mutagenic responses of the cells were measured and RBEs (D10, 2 chromatid aberrations/cell and 10 induced 6-thioguanine-resistant mutants) were calculated to be 3.8, 3.5, and 3.9, respectively for K1, and 1.4, 0.8, and 5.1, respectively, for xrs-5. With the exception of the RBE of less than 1 for alpha-induced aberrations in xrs-5, the results are consistent with the following conclusions: (1) alpha-particles are in general more effective cytotoxic, clastogenic and mutagenic agents than X-rays; (2) the primary lethal and clastogenic lesion induced by both X-rays and alpha-particles is probably a DNA double-strand break; (3) DNA double-strand breaks induced by alpha-radiation are less well repaired than those induced by X-rays, although a portion of alpha-induced damage is repairable; and (4) deficiencies in rejoining DNA double-strand breaks affect the clastogenic and cytotoxic effects of X-rays and alpha-radiation, not their mutagenic effects. The RBE of 0.8 for aberration induction in xrs-5 cells could reflect a deficiency in the ability of these cells to convert alpha-induced damage to chromosome aberrations. Alternatively, the RBE of less than 1 might reflect an unusual sensitivity of xrs-5 cells to alpha-induced G2 delays.
Shadley
J D
JD
Biological and Medical Research Division, Argonne National Laboratory, IL 60439.
Whitlock
J L
JL
Rotmensch
J
J
Atcher
R W
RW
Tang
J
J
Schwartz
J L
JL
D000512:Alpha Particles / Q000009:adverse effects; D000818:Animals; D001729:Bismuth / Q000009:adverse effects*; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects; D002869:Chromosome Aberrations; D002872:Chromosome Deletion; D006224:Cricetinae; D004247:DNA / Q000528:radiation effects*; D004252:DNA Mutational Analysis; D004307:Dose-Response Relationship, Radiation; D004351:Drug Resistance; D066298:In Vitro Techniques; D004369:Pentetic Acid / Q000494:pharmacology; D011868:Radioisotopes; D011886:Radon / Q000009:adverse effects*; D012044:Regression Analysis; D013866:Thioguanine; D014965:X-Rays / Q000009:adverse effects
D011868:Radioisotopes; D004369:Pentetic Acid; D004247:DNA; D013866:Thioguanine; D011886:Radon; D001729:Bismuth