ToxSci Advance Access published online on September 11, 2003
Toxicological Sciences, doi:10.1093/toxsci/kfg230
Toxicological Sciences © Society of Toxicology 2003; all rights reserved
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1 Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa 920-0934, Japan; Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Corporation, Kawaguchi 332-0012, Japan
* To whom correspondence should be addressed. E-mail: kizu{at}p.kanazawa-u.ac.jp.
We collected diesel exhaust particles (DEP) emitted from three diesel-engine vehicles, a car, a bus and a truck, in daily use, and prepared DEP extracts (DEPEs), designated as EC, EB or ET, respectively. The androgenic and antiandrogenic effects of the DEPE samples were examined by a luciferase reporter assay in human prostate carcinoma PC3/AR cells transiently transfected with a prostate specific antigen gene promoter-driven luciferase expression vector pGLPSA5.8. PC3/AR is a subline of human prostate carcinoma PC3 transformed to stably express wild-type human androgen receptor (AR). While DEPE samples did not exhibit any androgenic effect, they exerted antiandrogenic effect, inhibiting dihydrotestosterone (10 pM)-induced luciferase activity by 24 to 52% at an extract concentration of 10 µg/mL. The antiandrogenic effect was greater in the following order: ET>EB>EC. Co-treatment of PC3/AR cells with SKF-525A, a non-selective inhibitor of cytochrome P450 (CYP) enzymes, enhanced the antiandrogenic effect, indicating that the antiandrogenic effect is caused by intact species of DEPE constituents. The antiandrogenic effect of DEPE samples was reversed by
© 2003 Society of Toxicology
Endocrine Toxicology
Antiandrogenic Activities of Diesel Exhaust Particle Extracts in PC3/AR Human Prostate Carcinoma Cells
2 Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa 920-0934, Japan
3 Department of Urology, School of Medicine, Kanazawa University, Kanazawa 920-8641, Japan
4 Department of Molecular and Cellular Pharmacology, University of Miami School of Medicine, Miami, FL 33101, USA
5 Department of Biochemistry and Molecular Biology, University of Louisville School of Medicine, Louisville, KY 40292, USA
Abstract 
-naphthoflavone, an aryl hydrocarbon receptor (AhR) antagonist. The antiandrogenic activity of a DEPE sample correlated with its AhR agonist activity assayed in PC3/AR cells transiently transfected with CYP1A1 gene promoter-driven luciferase expression vector pLUC1A1. Equimolar mixtures of ten PAHs having four or more rings, structures found in the DEPEs, showed significant antiandrogenic effects and AhR agonist activity at concentrations equivalent to those found in DEPE samples. Further, DEPE samples elicited only antiandrogenic effects in recombinant yeast cells which express 
-galactosidase in response to androgen. A competitive AR binding assay showed that AR-binding constituents exist in DEPE samples, indicating that greater part of AR-binding constituents in DEPEs are AR antagonists. All these findings show that DEPE samples exhibit significant antiandrogenic effect in cell-based transcription assay and that this effect is due in part to the constituents with AhR agonist activity including PAHs and to the constituents with AR antagonist activity.
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