title: Reduction of androgen receptor expression by benzo[alpha]pyrene and 7,8-dihydro-9,10-epoxy-7,8,9,10-tetrahydrobenzo[alpha]pyrene in human lung cells.
abstract: 5Alpha-dihydrotestosterone significantly increased cell growth of lung adenocarcinoma cell line H1355. Benzo[alpha]pyrene (BaP) was a pulmonary carcinogen found in cigarette smoke. Treatment with 1microM BaP tremendously reduced constitutive androgen receptor (AR) expression, as determined with Western immunoblotting and the real-time RT-PCR assay, as well as testosterone-induced AR protein levels in H1355 cells. Similarly, 1microM BaP significantly reduced AR mRNA levels in human bronchial epithelial cells BEAS-2B. Although BaP, 2,3,7,8-tetrachlorodibenzo-p-dixin and polychlorinated biphenyl 126 activated aryl hydrocarbon receptor (AhR), which subsequently induced cytochrome P4501A1 (CYP1A1) and P4501B1 (CYP1B1) expression in H1355 cells, unexpectedly, neither TCDD nor PCB126 reduced AR expression. Antagonizing AhR activation and cytochrome P4501 activity with alpha-naphthoflavone, or inhibiting CYP1B1 activity with 2,4,3',5'-tetramethoxystilbene, however, prevented BaP-induced AR reduction. Furthermore, 7,8-dihydro-9,10-epoxy-7,8,9,10-tetrahydrobenzo[alpha]pyrene, a BaP carcinogenic metabolite catalyzed by CYP1A1 and CYP1B1, significantly reduced AR expression in H1355 cells and human lung fibroblasts WI-38. This was the first study that reports that BaP and BPDE reduced endogenous AR expression. These data suggest that metabolically activated BaP may disrupt androgen function by reducing AR levels in androgen-responsive organs.
authors.affiliation: Institute of Toxicology, Chung Shan Medical University, No. 110, Sector 1, Chien-Kuo N. Rd., Taichung 40 203, Taiwan, ROC. ppl@csmu.edu.tw
authors.forename: Pinpin
authors.initials: P
authors.lastname: Lin
authors.forename: Jinghua Tsai
authors.initials: JT
authors.lastname: Chang
authors.forename: Jiunn-Liang
authors.initials: JL
authors.lastname: Ko
authors.forename: Sheng-Hung
authors.initials: SH
authors.lastname: Liao
authors.forename: Wai-Sze
authors.initials: WS
authors.lastname: Lo
mesh_terms: D015123:7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide / Q000494:pharmacology*; D001189:Aryl Hydrocarbon Hydroxylases / Q000096:biosynthesis; D001564:Benzo(a)pyrene / Q000494:pharmacology*; D002273:Carcinogens / Q000494:pharmacology; D019363:Cytochrome P-450 CYP1A1 / Q000096:biosynthesis; D065633:Cytochrome P-450 CYP1B1; D004347:Drug Interactions; D004965:Estrogen Antagonists / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology; D015870:Gene Expression / Q000187:drug effects*; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology; D011078:Polychlorinated Biphenyls / Q000494:pharmacology; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology; D011944:Receptors, Androgen / Q000235:genetics / Q000378:metabolism*; D013739:Testosterone / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D002273:Carcinogens; D004965:Estrogen Antagonists; D000072317:Polychlorinated Dibenzodioxins; D011944:Receptors, Androgen; D001564:Benzo(a)pyrene; D013739:Testosterone; D015123:7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide; D011078:Polychlorinated Biphenyls; D001189:Aryl Hydrocarbon Hydroxylases; C585496:CYP1B1 protein, human; D019363:Cytochrome P-450 CYP1A1; D065633:Cytochrome P-450 CYP1B1; C023035:3,4,5,3',4'-pentachlorobiphenyl