INHIBITION OF ANDROGEN RECEPTOR-DEPENDENT TRANSCRIPTIONAL ACTIVITY BYDDT ISOMERS AND METHOXYCHLOR IN HEPG2 HUMAN HEPATOMA-CELLS

Recent reports have raised new concerns that chemicals in our environm ent may disrupt normal reproduction and development through inhibition of androgen receptor function. This heightened concern has also incre ased our need for methods that allow us to characterize chemical inter action with the androgen receptor. In this report we describe an andro gen receptor assay that utilizes the HepG2 human hepatoma cell line tr ansiently transfected with the human androgen receptor and an androgen -responsive reporter, We used this assay to characterize the interacti on with the androgen receptor of several steroidal and nonsteroidal ch emicals, including isomers of DDT and methoxychlor. Chemicals were tes ted either in the absence (for determining agonist activity) or presen ce of 10(-7) IM dihydrotestosterone (for determining antagonist activi ty), Testosterone and dihydrotestosterone were equally potent agonists in this assay. Estradiol and progesterone displayed partial agonist/a ntagonist activity. Flutamide was a complete agonist, whereas its hydr oxylated metabolite, hydroxyflutamide, only partially antagonized and displayed some agonist activity at 10(-6) M and above, o,p'-DDT, o,p'- DDE, o,p'-DDD, p,p'-DDT, p,p'-DDE, and p,p'-DDD all behaved as antagon ists at concentrations above 10(-6) M, p,p'-DDE also showed some agoni st activity at 10(-5) M, Methoxychlor was only weakly antagonistic whi le its hydroxylated metabolite, HPTE, was approximately 10-fold more p otent. Our results demonstrate that the HepG2 assay is a sensitive and specific method for detecting chemical interaction with the androgen receptor. This reporter gene assay, which we have used to characterize interaction with both the estrogen and androgen receptors, coupled wi th more extensive in vivo studies, should be useful for determining th e role of multiple steroid receptors in the mechanism of action of end ocrine active chemicals. (C) 1998 Academic Press.