Dietary conjugated linoleic acid modulation of phorbol ester skin tumor promotion.
The fatty acid derivative conjugated dienoic linoleate (CLA) has been shown to inhibit initiation and postinitiation stages of carcinogenesis in several experimental animal models. The goal of the present study was to determine the role of increasing levels of dietary CLA in mouse skin tumor promotion elicited by 12-O-tetradecanoylphorbol-13-acetate (TPA). Mice were fed control (no CLA) diet during initiation, then switched to diets containing 0.0%, 0.5%, 1.0%, or 1.5% (wt/wt) CLA during skin tumor promotion by TPA. Body weights of mice fed 0.5%, 1.0%, or 1.5% CLA were similar to each other but were significantly lower (p < 0.05) than weights of mice fed no CLA (0.0%) throughout promotion. A reduction in papilloma incidence was observed in mice fed 1.5% CLA from Weeks 8 to 24 compared with mice fed diets containing 0.0-1.0% CLA (p < 0.05). Twenty-four weeks after tumor promotion was begun, diets containing 1.0% and 1.5% CLA inhibited tumor yield (4.94 and 4.35 tumors/mouse, respectively) compared with diets without CLA (0.0% CLA, 6.65 tumors/mouse, p < 0.05) or 0.5% CLA (5.92 tumors/mouse, p < 0.05). These data indicate that CLA inhibits tumor promotion in a manner that is independent of its anti-initiator activity. Further studies are warranted in identifying cellular mechanisms that are likely to be involved with the antipromoter effects of CLA.
Belury
M A
MA
Department of Foods and Nutrition, Purdue University, West Lafayette, IN 47907, USA.
Nickel
K P
KP
Bird
C E
CE
Wu
Y
Y
D000818:Animals; D001835:Body Weight; D004042:Dietary Fats, Unsaturated / Q000627:therapeutic use*; D005260:Female; D019787:Linoleic Acid; D008041:Linoleic Acids / Q000627:therapeutic use*; D051379:Mice; D010212:Papilloma / Q000139:chemically induced; D012878:Skin Neoplasms / Q000139:chemically induced* / Q000517:prevention & control*; D013755:Tetradecanoylphorbol Acetate; D013997:Time Factors
D004042:Dietary Fats, Unsaturated; D008041:Linoleic Acids; D019787:Linoleic Acid; D013755:Tetradecanoylphorbol Acetate