Null effect of dietary restriction on prostate carcinogenesis in the Wistar-Unilever rat.
Chronic dietary restriction inhibits carcinogenesis in several sites in laboratory animals. To determine the effects of dietary restriction on prostate carcinogenesis, prostate cancers were induced in male Wistar-Unilever rats by a sequential regimen of cyproterone acetate (50 mg/day; 21 days); testosterone propionate (100 mg/kg/day; 3 days); N-methyl-N-nitrosourea [MNU; 30 mg/kg; single dose]; and testosterone (subcutaneous implants of 2 pellets containing 40 mg each). Dietary restriction (0% [ad libitum control], 15%, or 30%) was initiated 2 wk post-MNU, and continued until study termination at 12 mo. Dietary restriction induced a rapid suppression of body weight gain but conferred no protection against prostate carcinogenesis. 74% of carcinogen-treated ad libitum controls developed accessory sex gland cancers, versus cancer incidences of 64% and 72% in groups restricted by 15% and 30%, respectively. Similarly, 44% of dietary controls developed cancers limited to the dorsolateral/prostate, versus incidences of 45% and 53% in groups restricted by 15% and 30%. The results of the present study do not support the hypothesis that prostate carcinogenesis can be prevented by reducing caloric intake. Reducing mean body weight by up to 25% through chronic dietary restriction has no effect on the induction of prostate cancers in the Wistar-Unilever rat model.
McCormick
David L
DL
Life Sciences Group, IIT Research Institute, Chicago, IL 60616, USA. dmccormick@iitri.org
Johnson
William D
WD
Haryu
Todd M
TM
Bosland
Maarten C
MC
Lubet
Ronald A
RA
Steele
Vernon E
VE
D000818:Animals; D002273:Carcinogens / Q000633:toxicity*; D017373:Cyproterone Acetate / Q000633:toxicity; D004038:Diet, Reducing; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008297:Male; D008770:Methylnitrosourea / Q000633:toxicity; D015995:Prevalence; D011471:Prostatic Neoplasms / Q000139:chemically induced / Q000453:epidemiology / Q000517:prevention & control*; D051381:Rats; D017208:Rats, Wistar; D013739:Testosterone / Q000097:blood / Q000633:toxicity; D043343:Testosterone Propionate / Q000633:toxicity; D016896:Treatment Outcome; D015430:Weight Gain / Q000187:drug effects*
D002273:Carcinogens; D013739:Testosterone; D017373:Cyproterone Acetate; D008770:Methylnitrosourea; D043343:Testosterone Propionate