Journal Article

Lung Tumor Development in Mice Exposed to Tobacco Smoke and Fed β-Carotene Diets

Ute C. Obermueller-Jevic, Imelda Espiritu, Ana M. Corbacho, Carroll E. Cross and Hanspeter Witschi

in Toxicological Sciences

Volume 69, issue 1, pages 23-29
Published in print September 2002 | ISSN: 1096-6080
Published online September 2002 | e-ISSN: 1096-0929 | DOI: http://dx.doi.org/10.1093/toxsci/69.1.23
Lung Tumor Development in Mice Exposed to Tobacco Smoke and Fed β-Carotene Diets

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In human clinical trials it was found that the putative chemopreventive agent β-carotene not only failed to protect active smokers against the carcinogenic action of tobacco smoke, but actually increased their risk of developing lung cancer. In preclinical animal studies, β-carotene had been effective against some chemically induced cancers, but not against tumors in the respiratory tract. We exposed male strain A/J mice to tobacco smoke at a concentration of 140 mg/m3 of total suspended particulate matter, 6 h a day, 5 days a week, for either 4 or 5 months, followed by a recovery period in air for 4 or 5 months, or for 9 months without recovery period. β-carotene was added in the form of gelatin beadlets to the AIN-93G diet either during or following tobacco smoke exposure at concentrations of 0.005, 0.05 and 0.5%. In the supplement-fed animals, plasma and lung levels of β-carotene were higher than they were in animals fed control diets. Exposure to tobacco smoke increased rather than decreased plasma β-carotene levels, but had no significant effect on lung levels. After 9 months, lung tumor multiplicities and incidence were determined. Tobacco smoke increased both lung tumor multiplicities and incidences, but β-carotene failed to modulate tumor development under all exposure conditions. Animal studies in a model of tobacco smoke carcinogenesis would thus have predicted the absence of any beneficial effects of β-carotene supplementation in current or former smokers, but would have failed to anticipate the increase in lung cancer risk.

Keywords: β-carotene; lung tumors; cigarette smoke; chemoprevention; strain A mice

Journal Article.  6335 words. 

Subjects: Medical Toxicology ; Toxicology (Non-medical)

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