Effect of TPA, okadaic acid and 1 alpha,25-dihydroxyvitamin D3 on neoplastic transformation induced by 60Co gamma-rays or 252Cf fission neutrons in Balb/c 3T3 cells.
The effects of 12-O-tetradecanoylphorbol-13-acetate (TPA), 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25(OH)2D3] and okadaic acid were individually examined on the neoplastic transformation of Balb/c 3T3 cells which were exposed to either 60Co gamma-rays or 252Cf fission neutrons. The addition of 1 alpha,25(OH)2D3, or TPA, enhanced the transformation induced by gamma-rays or low doses of fission neutrons. No enhancement was observed by the addition of okadaic acid except at toxic concentrations (5 ng/ml) and with higher doses of radiation. Moreover, the enhancement of transformation by either 1 alpha,25(OH)2D3 or TPA decreased as the radiation dose was increased. The enhancement ratio, calculated by least-square analysis from 0 Gy to 1 Gy, was greater for 1 alpha,25(OH)2D3 than for TPA, and also greater for gamma-ray irradiation than for neutron irradiation. These results suggest that the promotion of radiation-induced transformation depends on the level of the initial damage caused by radiation; and that the differences in the enhancement properties of different chemicals may be due to different individual triggering mechanisms involved in the transformation process.
Tauchi
H
H
Department of Radiation Biology, Hiroshima University, Japan.
Enomoto
T
T
Sawada
S
S
D016475:3T3 Cells; D000818:Animals; D002117:Calcitriol / Q000494:pharmacology*; D002471:Cell Transformation, Neoplastic / Q000187:drug effects / Q000528:radiation effects*; D004988:Ethers, Cyclic / Q000494:pharmacology*; D005720:Gamma Rays; D051379:Mice; D008807:Mice, Inbred BALB C; D009502:Neutrons; D019319:Okadaic Acid; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
D004988:Ethers, Cyclic; D019319:Okadaic Acid; D002117:Calcitriol; D013755:Tetradecanoylphorbol Acetate