Publications by authors named "Brad Geatrix"

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Beta-carotene interaction with NNK in the AJ-mouse model: effects on cell proliferation, tumor formation and retinoic acid responsive genes.

Biochim Biophys Acta 2005 May 27;1740(2):179-88. Epub 2005 Jan 27.

Build. 221/106, DSM Nutritional Products Ltd., R and D, Human Nutrition and Health P.O. Box 3255, CH-4002 Basel, Switzerland.

We studied the influence of beta-carotene on the tobacco smoke carcinogen 4-(N-Methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung tumor development in the A/J-mouse model. The normally low beta-carotene absorption was facilitated with a diet enriched in fat and bile salt, resulting in plasma and lung tissue levels similar to humans. beta-Carotene enhanced NNK-induced early bronchial cell proliferation, however, this effect was not predictive for later tumor development. Tumor multiplicity was not significantly affected by beta-carotene, neither in carcinogen-initiated nor in uninitiated mice, and regardless of dose and time point of supplementation during tumor development. RARbeta isoform and CYP26 gene expression levels analyzed by quantitative RT-PCR were weakly, but significantly, inversely correlated and showed evidence for altered retinoid signaling and catabolism in the lungs of NNK-initiated, beta-carotene supplemented mice. However, this interaction did not translate into enhanced tumor multiplicity. These results indicate that impaired retinoid signaling is not likely a key factor in lung tumorigenesis in this mouse model.
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May 2005