TRANSFECTION OF HUMAN CYTOCHROME-P-450 REDUCTASE CDNA AND ITS EFFECT ON THE SENSITIVITY TO TOXINS

NADPH-cytochrome P-450 reductase (CYPR; EC 1.6.2.4) is an essential en zyme for the catalytic function of cytochromes and is also regarded as being implicated in drug activation. To examine whether CYPR is direc tly involved in the drug metabolism, a cDNA encoding human CYPR was st ably transfected into Chinese hamster ovary cells. Three clonal cell l ines were identified which expressed increased levels of CYPR activity (9.3- to 11.2-fold). Western blot analysis indicated that CYPR-transf ectant cells contained markedly elevated levels of CYPR protein, while wild-type Chinese hamster ovary cells contained low levels. They show ed 1.8- to 3.3-fold higher sensitivity to Adriamycin, 2.1- to 3.0-fold higher sensitivity to mitomycin C, and 2.9- to 4.3-fold higher sensit ivity to paraquat than wild-type cells. We also studied other common-u se anticancer agents: vinblastine, vincristine, VP-16, and cisplatin, but there were no differences observed in the sensitivity. This report provides the first evidence that transfection of human CYPR into mamm alian cells is concerned in the sensitivity to some drugs.