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Antitumor activity of beta-carotene, canthaxanthin and phytoene
Abstract:
Mice were given either beta-carotene or either of two carotenoids with no vitamin A activity--canthaxanthin or phytoene--or placebo. Skin tumors were induced in each group by each of three methods: (1) UV-B (290--320 nm); (2) dimethylbenz(a)anthracene (DMBA)/croton oil applications; (3) DMBA followed by low-dose UV-B. For tumors induced by UV-B alone, beta-carotene-phytoene- and canthaxanthin-treated mice developed fewer tumors per mouse, with a delay in tumor appearance, than did control mice. For tumors induced by DMBA/croton oil or DMBA/UV-B, mice receiving beta-carotene showed a significant difference in tumor numbers and appearance time from placebo mice; phytoene and canthaxanthin treatment had no effect.
Insights
Beta-carotene and other carotenoids may offer protection against UV-induced skin tumors in mice. However, only beta-carotene demonstrated significant tumor reduction when chemical carcinogens were involved.
Area of Science:
- Photodermatology
- Carotenoid research
- Chemical carcinogenesis
Background:
- Carotenoids are pigments found in plants, some of which are precursors to Vitamin A.
- The role of specific carotenoids, like beta-carotene, canthaxanthin, and phytoene, in skin cancer prevention is an area of ongoing research.
- Understanding the differential effects of various carotenoids on skin tumor development is crucial for assessing their potential chemopreventive properties.
Purpose of the Study:
- To investigate the protective effects of beta-carotene, canthaxanthin, and phytoene against skin tumor induction in mice.
- To compare the efficacy of these carotenoids under different tumor induction methods: UV-B radiation, chemical carcinogens (DMBA/croton oil), and a combination of both.
- To determine if carotenoids lacking vitamin A activity offer any photoprotective or chemoprotective benefits.
Main Methods:
- Mice were administered beta-carotene, canthaxanthin, phytoene, or a placebo.
- Skin tumors were induced using three distinct methods: UV-B radiation (290-320 nm), topical application of dimethylbenz(a)anthracene (DMBA) with croton oil, and DMBA followed by low-dose UV-B exposure.
- Tumor incidence, number of tumors per mouse, and time to tumor appearance were recorded and compared between groups.
Main Results:
- Beta-carotene, phytoene, and canthaxanthin treatments resulted in fewer UV-B-induced tumors and delayed tumor onset compared to the placebo group.
- In cases of tumors induced by DMBA/croton oil or DMBA/UV-B, only beta-carotene administration showed a significant reduction in tumor number and a delay in tumor appearance compared to placebo.
- Canthaxanthin and phytoene had no significant effect on tumors induced by chemical carcinogens, even when combined with UV-B.
Conclusions:
- Beta-carotene exhibits protective effects against both UV-induced and chemically induced skin tumors in mice.
- Carotenoids with no vitamin A activity (canthaxanthin and phytoene) demonstrate efficacy against UV-induced tumors but not against chemically induced ones.
- The findings suggest a differential mechanism of action for various carotenoids in skin cancer prevention, with beta-carotene showing broader protective capabilities.