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.
Department of Radiation Biology, Hiroshima University, Japan.
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Tauchi
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Enomoto
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Sawada
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