Potent preventive action of alpha-carotene against carcinogenesis: spontaneous liver carcinogenesis and promoting stage of lung and skin carcinogenesis in mice are suppressed more effectively by alpha-carotene than by beta-carotene.
Although beta-carotene has been considered to be a key cancer preventive agent in green and yellow vegetables, other types of carotenoids, such as alpha-carotene, may also contribute to anticarcinogenic action, since these carotenoids usually coexist with beta-carotene and are detectable in human blood and tissues. In this study, we compared the inhibitory effect of natural alpha-carotene, obtained from palm oil, with that of beta-carotene on spontaneous liver carcinogenesis in C3H/He male mice. The mean number of hepatomas per mouse was significantly decreased by alpha-carotene supplementation (per os administration in drinking water at a concentration of 0.05%, ad libitum) as compared with that in the control group (P < 0.001, Student's t test). On the other hand, beta-carotene, at the same dose as alpha-carotene, did not show any such significant difference from the control group. Furthermore, we also compared the antitumor-promoting activity of alpha-carotene with that of beta-carotene against two-stage mouse lung carcinogenesis (initiator, 4-nitroquinoline 1-oxide; promoter, glycerol). alpha-Carotene, but not beta-carotene, reduced the number of lung tumors per mouse to about 30% of that in the control group (P < 0.001, Student's t test). The higher potency of the antitumor-promoting action of alpha-carotene compared to beta-carotene was confirmed in other experimental systems; e.g., alpha-carotene was also found to have a stronger effect than beta-carotene in suppressing the promoting activity of 12-O-tetradecanoylphorbol-13-acetate on skin carcinogenesis in 7,12-dimethylbenz[a]anthracene-initiated mice. These results suggest that not only beta-carotene, but also other types of carotenoids, such as alpha-carotene, may play an important role in cancer prevention.
Murakoshi
M
M
Department of Biochemistry, Kyoto Prefectural University of Medicine, Japan.
Nishino
H
H
Satomi
Y
Y
Takayasu
J
J
Hasegawa
T
T
Tokuda
H
H
Iwashima
A
A
Okuzumi
J
J
Okabe
H
H
Kitano
H
H
D015112:4-Nitroquinoline-1-oxide; D015127:9,10-Dimethyl-1,2-benzanthracene; D000284:Administration, Oral; D000818:Animals; D002338:Carotenoids / Q000627:therapeutic use*; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D008113:Liver Neoplasms / Q000517:prevention & control*; D008175:Lung Neoplasms / Q000139:chemically induced / Q000517:prevention & control*; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D009955:Ornithine Decarboxylase / Q000032:analysis; D010212:Papilloma / Q000139:chemically induced / Q000517:prevention & control; D012878:Skin Neoplasms / Q000139:chemically induced / Q000517:prevention & control*; D013047:Specific Pathogen-Free Organisms; D013755:Tetradecanoylphorbol Acetate; D019207:beta Carotene
D019207:beta Carotene; D002338:Carotenoids; C041635:alpha-carotene; D015112:4-Nitroquinoline-1-oxide; D015127:9,10-Dimethyl-1,2-benzanthracene; D009955:Ornithine Decarboxylase; D013755:Tetradecanoylphorbol Acetate