||Inhibition of Morphological Transformation of C3H10T1/2CL8 Mouse Embryo Cells by Multiple Carcinogen Treatments.
Nesnow, S. ;
Garland, H. ;
Curtis, G. ;
||Health Effects Research Lab., Research Triangle Park, NC. ;Environmental Health Research and Testing, Inc., Research Triangle Park, NC.
Transformed cell line ;
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C3H10T1/2CL8 cells treated on the first day after seeding with benzo(a)pyrene (B(a)P) and then treated again with B(a)P displayed an enhanced or inhibited response of morphological transformation depending on the time of the second treatment. When the second treatment was performed up to 8 days after seeding, the cells expressed a 60% increase in Type II or Type III foci per dish after adjusting for the total dose administered. If the second treatment was administered from 10 days to 26 days after seeding, the cells exhibited up to 100% inhibition of morphological transformation. Enhancement or inhibition seemed to be related to the growth state of the cells as enhancement was observed only in log phase growth and inhibition in preconfluent to confluent cells. The extent of inhibition was related to the concentration of B(a)P administered in the second treatment. Two additional carcinogens were examined for their ability to inhibit B(a)P induced morphological transformation when administered to cells 22 days after the initial B(a)P treatment: 3-methylcholanthrene (3MC) and n-methyl-n'-nitro-n-nitrosoguanidine (MNNG). Both 3MC and MNNG inhibited transformation as a function of concentration with 3MC the more active inhibitor. (Copyright (c) 1989 Elsevier Scientific Publishers Ireland Ltd.)