Effects of Dietary Xanthophylls, Canthaxanthin and Astaxanthin on N-Methyl-N-nitrosourea-induced Rat Mammary Carcinogenesis.
BACKGROUND
Natural xanthophylls, canthaxanthin and astaxanthin are known to exhibit anticancer activity. However, the dietary effects of canthaxanthin and astaxanthin on N-methyl-N-nitrosourea (MNU)-induced mammary cancer remain controversial, and their mechanisms of action have not been clearly identified.


METHODS
Three-week-old female Sprague-Dawley rats were fed a xanthophyll-free (basal diet) diet or experimental diets containing canthaxanthin or astaxanthin (0.04% and 0.4%) for 5 weeks (until 8 weeks of age), after which all rats were provided the basal diet (n=15 each). Rats were administered MNU at 6 weeks of age, and the incidence of mammary tumors at 20 weeks of age was compared. The expression of adiponectin in mammary adipose tissues taken at 7 weeks of age was also compared.


RESULTS
Compared to the basal diet group, the 0.4% (but not the 0.04%) astaxanthin diet significantly reduced the incidence of palpable mammary carcinoma (92% vs. 42%; p<0.05), while the low and high canthaxanthin diets produced no significant inhibition. Adiponectin immunoblotting showed significantly higher expression in the 0.4% astaxanthin diet group, while the other groups were similar to the basal diet group.


CONCLUSIONS
High concentrations of astaxanthin suppress MNU-induced mammary carcinoma. Changes in adiponectin may be involved in the mechanism of action.
Department of Pathology 2, Kansai Medical University, Hirakata, Japan yurit@hirakata.kmu.ac.jp.
Takashi
T
Yuri
Department of Pathology 2, Kansai Medical University, Hirakata, Japan.
Katsuhiko
K
Yoshizawa
Department of Pathology 2, Kansai Medical University, Hirakata, Japan.
Yuko
Y
Emoto
Department of Pathology 2, Kansai Medical University, Hirakata, Japan.
Yuichi
Y
Kinoshita
Department of Pathology 2, Kansai Medical University, Hirakata, Japan.
Michiko
M
Yuki
Department of Pathology 2, Kansai Medical University, Hirakata, Japan.
Airo
A
Tsubura
D052242:Adiponectin / Q000378:metabolism; D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism; D000284:Administration, Oral; D000818:Animals; D016644:Canthaxanthin / Q000008:administration & dosage*; D004032:Diet; D005260:Female; D015151:Immunoblotting; D008321:Mammary Glands, Animal / Q000187:drug effects / Q000378:metabolism; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced / Q000517:prevention & control*; D008770:Methylnitrosourea; D017207:Rats, Sprague-Dawley; D024341:Xanthophylls / Q000008:administration & dosage*
D052242:Adiponectin; D024341:Xanthophylls; D016644:Canthaxanthin; D008770:Methylnitrosourea; C005948:astaxanthine
Xanthophyll; adiponectin; astaxanthin; canthaxanthin; mammary cancer