Androgen manipulation alters oxidative DNA adduct levels in androgen-sensitive prostate cancer cells grown in vitro and in vivo.
Intracellular reactive oxygen species (ROS) may cause oxidative DNA damage, resulting in the formation of adducts such as 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG) and the cyclic pyrimidopurinone N-1, N(2) malondialdehyde-2'-deoxyguanosine (M(1)dG). These adducts have been associated with carcinogenesis, genomic instability and clonal evolution. We tested two hypotheses in human prostate cancer cells grown in vitro and in a xenograft model: (1) treatment of androgen-sensitive cells with DHT increases levels of oxidative DNA adduct levels; (2) flutamide, a competitive androgen receptor antagonist, prevents DHT-induced changes. Levels of M(1)dG and 8-oxo-dG adducts were determined by immunoslot blot and liquid chromatography-tandem mass spectrometry. M(1)dG and 8-oxo-dG levels were significantly higher than control levels in LNCaP cells exposed to supra-physiological concentrations (25-100 nM) of DHT (both P<0.05 by ANOVA). Flutamide pre-treatment completely prevented this increase. In the xenograft model, tumour levels of M(1)dG were decreased by 46% (P=0.001 by Mann-Whitney Test) in flutamide-treated animals compared to controls. The changes demonstrated suggest that oxidative DNA adducts may serve as biomarkers of the efficacy of androgen manipulation in chemoprevention trials.
Pathak
Sanjeev
S
Cancer Biomarkers and Prevention Group, Department of Cancer Studies and Molecular Medicine, University of Leicester, Leicester LE2 7LX, UK.
Singh
Rajinder
R
Verschoyle
Richard D
RD
Greaves
Peter
P
Farmer
Peter B
PB
Steward
William P
WP
Mellon
J Kilian
JK
Gescher
Andreas J
AJ
Sharma
Ricky A
RA
D000728:Androgens / Q000494:pharmacology*; D000818:Animals; D045744:Cell Line, Tumor; D018736:DNA Adducts / Q000378:metabolism*; D004249:DNA Damage; D013196:Dihydrotestosterone / Q000494:pharmacology; D005485:Flutamide / Q000494:pharmacology; D006801:Humans; D008297:Male; D051379:Mice; D009368:Neoplasm Transplantation; D009376:Neoplasms, Hormone-Dependent / Q000378:metabolism*; D011471:Prostatic Neoplasms / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*
D000728:Androgens; D018736:DNA Adducts; D017382:Reactive Oxygen Species; D013196:Dihydrotestosterone; D005485:Flutamide