Inhibition of rat mammary gland chemical carcinogenesis by dietary dehydroepiandrosterone or a fluorinated analogue of dehydroepiandrosterone.
The chemopreventive efficacy of p.o. administered dehydroepiandrosterone (DHEA), DHEA plus N-(4-hydroxyphenyl)retinamide (4-HPR), or 16 alpha-fluoro-5-androsten-17-one (DHEA analogue 8354) was examined in rats treated with N-methyl-N-nitrosourea (MNU; 50 mg/kg body weight, i.v.) at 50 days of age. Semipurified diet (AIN-76A) containing each steroid alone, or DHEA plus 4-HPR, was administered during initiation (-1 week to +1 week post-MNU), promotion/progression (+1 week post-MNU to termination), or both phases (-1 week post-MNU to termination) of the carcinogenic process. Neither DHEA nor DHEA analogue 8354 (0.2%, w/w) significantly affected the initiation of mammary cancer when administered alone; however, DHEA (0.2%, w/w) plus 4-HPR (1 mmol/kg diet) significantly reduced cancer multiplicity (26%) when given during initiation. All three treatments were strongly effective when given during promotion/progression, significantly reducing mammary cancer multiplicity by 77% (DHEA), 84% (DHEA/4-HPR), and 66% (DHEA analogue 8354), relative to carcinogen controls. Cancer incidence was significantly inhibited by DHEA (33% inhibition) and DHEA/4-HPR (24% reduction) during promotion/progression. However, the most effective chemopreventive treatment encompassed both phases of carcinogenesis. Thus, under these conditions, DHEA (0.2% or 0.1%, w/w) reduced cancer incidence (52% and 32% reductions, respectively) and multiplicity (91% and 86% reductions, respectively). Further reduction in mammary cancer incidence was observed in animals that received DHEA (both doses) plus 4-HPR (1 and 0.5 mmol/kg diet, respectively). DHEA analogue 8354 (0.2% or 0.1%, w/w) given for the duration of the study reduced only cancer multiplicity (61% and 56% reductions, respectively). Tumor-related mortality was significantly lower in rats that received long-term treatment with DHEA or DHEA/4-HPR, when compared with carcinogen controls. Except for a slight, but significant, postcarcinogen decrease in the mean body weights of rats treated concomitantly with DHEA (plus or minus 4-HPR) and MNU, additional gross manifestations of steroid-induced toxicity were not observed.
Ratko
T A
TA
Laboratory of Pathophysiology, IIT Research Institute, Chicago, Illinois 60616.
Detrisac
C J
CJ
Mehta
R G
RG
Kelloff
G J
GJ
Moon
R C
RC
D000736:Androstenes / Q000008:administration & dosage / Q000627:therapeutic use*; D000818:Animals; D000970:Antineoplastic Agents; D003687:Dehydroepiandrosterone / Q000008:administration & dosage / Q000627:therapeutic use*; D004032:Diet; D004359:Drug Therapy, Combination; D005260:Female; D017313:Fenretinide; D008325:Mammary Neoplasms, Experimental / Q000473:pathology / Q000517:prevention & control*; D008770:Methylnitrosourea; D051381:Rats; D011919:Rats, Inbred Strains; D014212:Tretinoin / Q000031:analogs & derivatives / Q000627:therapeutic use
D000736:Androstenes; D000970:Antineoplastic Agents; C066783:16-fluoro-5-androsten-17-one; D017313:Fenretinide; D003687:Dehydroepiandrosterone; D014212:Tretinoin; D008770:Methylnitrosourea