THE DEVELOPMENT OF A HUMAN CELL-LINE STABLY EXPRESSING HUMAN CYP3A4 - ROLE IN THE METABOLIC-ACTIVATION OF AFLATOXIN-B1 AND COMPARISON TO CYP1A2 AND CYP2A3

We have developed a human lymphoblastoid cell line, designated 3A4/Hol, which stably expresses human CYP3A4 cDNA. This cell line exhibited testosterone 6beta-hydroxylase activity, produced immunologically detectable CYP3A4 protein and was more sensitive to the cytotoxicity and mutagenicity of the carcinogenic mycotoxin aflatoxin B1 (AFB1) than was the parent cell line. The concentration-response for AFB1 cytotoxicity and mutagenicity in 3A4/Hol cells was compared to the responses of isogenic cell lines expressing comparable levels of human CYP1A2 (1A2/Hyg cells) and human CYP2A3 (2A3/Hyg cells). 1A2/Hyg cells were 3- to 6-fold more sensitive than 3A4/Hol cells to AFB1-induced mutation. 3A4/Hol cells were 10- to 15-fold more sensitive to AFB1-induced mutation than 2A3/Hyg cells. The differences in mutagenicity were supported by the relative binding of [H-3]AFB1 to cellular DNA.