Promotion of BALB/3T3 cell transformation by the okadaic acid class of tumor promoters, okadaic acid and dinophysistoxin-1.
Okadaic acid and dinophysistoxin-1 are non-12-O-tetradecanoylphorbol-13-acetate (non-TPA)-type tumor promoters, which enhance chemically induced tumorigenesis on mouse skin through a different mechanism from that of TPA. In the present study, we examined the promoting effects of these okadaic acid class tumor promoters on a two-stage transformation using BALB/3T3 cells which was designed to simulate in vivo two-stage carcinogenesis. Cells were treated first with a low dose of the initiator 3-methylcholanthrene (MCA) and then with a test chemical. Okadaic acid and dinophysistoxin-1 significantly enhanced the MCA-induced cell transformation. Okadaic acid tetramethyl ether, an inactive compound, did not affect the transformation of MCA-treated cells. The okadaic acid class of tumor promoters failed to induce transformation without pretreatment by MCA. Okadaic acid did not show initiating activity in the two-stage transformation assay in which cells were treated first with okadaic acid and then with TPA. These results indicate that this transformation assay with BALB/3T3 cells is useful to predict tumor-promoting activity of non-TPA-type as well as TPA-type tumor promoters, before long-term in vivo two-stage carcinogenesis experiments are carried out.
Sakai
A
A
Division of Microbiology, National Institute of Hygienic Sciences, Tokyo.
Fujiki
H
H
D000818:Animals; D002273:Carcinogens; D002471:Cell Transformation, Neoplastic / Q000139:chemically induced*; D002478:Cells, Cultured; D004141:Dinoflagellida; D004988:Ethers, Cyclic / Q000494:pharmacology*; D008387:Marine Toxins; D051379:Mice; D008815:Mice, Inbred Strains; D019319:Okadaic Acid / Q000031:analogs & derivatives; D011714:Pyrans / Q000494:pharmacology*
D002273:Carcinogens; D004988:Ethers, Cyclic; D008387:Marine Toxins; D011714:Pyrans; D019319:Okadaic Acid; C051904:dinophysistoxin 1