Nairn R S, Tang M S, Wang R M, Adair G M, Humphrey R M
University of Texas System Cancer Center, Research Division, Smithville 78957.
Carcinogenesis. 1988 Aug;9(8):1369-75. doi: 10.1093/carcin/9.8.1369.
The effects of 2-aminofluorene (AF) DNA damage on cytotoxicity and DNA-mediated genetic transformation were investigated in Chinese hamster ovary (CHO) cells. N-Acetoxy-2-acetylaminofluorene (NA-AAF) treatment of DNA repair-proficient AT3-2 cells and UVL-10, a UV-hypersensitive mutant cell line derived from AT3-2, showed that UVL-10 cells were markedly more sensitive than AT3-2 cells to NA-AAF cytotoxicity. Analysis of cellular DNA from NA-AAF-treated cell cultures showed that AF was the predominant DNA adduct formed in both cell lines, while formation of 2-acetylaminofluorene (AAF) DNA adducts was not detected in cellular DNA samples of either cell line. Analysis of AF adduct removal showed that kinetics and extent of AF removal were similar in both cell lines. The effects of cellular processing of AAF DNA adducts in CHO cells were examined by introducing plasmid pSV2gpt DNA containing AAF damage into AT3-2 and UVL-10 cell lines by transfection. For comparative purposes, AF-containing pSV2gpt was also used in parallel experiments. In transfection experiments with AAF-containing pSV2gpt DNA, yields of gpt+ transformants declined relative to control frequencies in a much more pronounced manner in repair-deficient UVL-10 cells than in repair-proficient AT3-2 cells. In contrast, transfection with pSV2gpt DNA containing AF adducts had no apparent effect on transformation frequencies in either cell line, even at very high levels of modification. Results of co-transformation experiments in which transfected AAF-containing pSV2gpt DNA molecules were not subjected to selection for phenotype showed that in repair-deficient UVL-10 cells, AAF damage in pSV2gpt apparently interfered with the ultimate association of transfected DNA with recipient cell DNA.
