Transcriptomics does not show adverse effects of b-carotene in A/J mice exposed to smoke for 2 weeks Emmanuelle Kuntz a,c , Ju ¨ rgen Borlak b , Georges Riss a , Claude-Pierre Aebischer a , Heinrich Bachmann a,d , Nicole Seifert a , Petra Buchwald Hunziker a , Do ¨rte So ¨lle b , Willi Hunziker a,e , Regina Goralczyk a , Karin Wertz a, * a DSM Nutritional Products, Human Nutrition and Health, P.O. Box 3255, Building 241/421, CH-4002 Basel, Switzerland b Fraunhofer Institute or Toxicology and Experimental Medicine, Drug Research and Clinical Inhalation, Hannover, Germany c RCC Ltd., Zelgliweg 1, 4452 Itingen, Switzerland d Herbonis AG, Grellingerstrasse 23, P.O. Box 4001, 4052 Basel, Switzerland e Frimorfo Ltd., Chemin du Musee 12, P.O. Box 191, 1705 Fribourg, Switzerland Received 22 December 2006, and in revised form 17 June 2007 Available online 18 July 2007 Abstract b-Carotene (bC) supplementation in smokers was unexpectedly associated with increased incidence of lung cancer versus smoking alone. We performed a study in A/J mice to explore possible bC/cigarette smoke (CS) interactions potentially influencing lung cancer risk in smokers. A/J mice received a diet containing 120 or 600 ppm bC for six weeks, and exposed to mainstream CS (140 mg total sus- pended particulates/m 3 ) during the last two weeks. Lung transcriptomics analysis revealed that CS induced drug metabolism, oxidative stress, extracellular matrix (ECM) degradation, inflammation markers, and apoptosis. bC reduced CS-induced inflammation markers and ECM degradation. bC modulated the CS effect on apoptosis without a clear pro- or anti-apoptotic trend. bC alone induced only minor changes of gene expression. In conclusion, bC/CS interactions caused gene regulations in lungs. CS was the main effector. The gene regulations overall did not indicate that bC exacerbated CS effects. Dose-dependency of bC effects was minor and not detectable by genome-wide data mining. Ó 2007 Elsevier Inc. All rights reserved. Keywords: b-Carotene; Cigarette smoke exposure; Lung cancer; Retinoic acid Lung cancer is the most common cancer in the world and tobacco smoking is the major risk factor, accounting for about 90% of the cases [1]. A considerable body of epi- demiological evidence demonstrates an association of high intake of fruits and vegetables or high bC plasma levels with a lower risk of lung cancer [2]. These findings were confirmed in preclinical studies [3,4]. Unexpectedly, in three large-scale clinical intervention trials, bC supplemen- tation was either not effective in lung cancer prevention [5], or was—in heavy smokers—associated with increased lung cancer incidence [6,7]. The molecular mechanism(s), by which bC 1 interferes with lung cancer in heavy smokers, is as yet unknown, but several hypotheses have been put forward. These include, e.g., CYP activation, retinoic acid (RA) depletion followed by disturbed retinoid signaling, and pro-oxidant effects of bC [8]. So far, studies in ferrets are the only published efforts to unravel the mechanism(s) explaining the unexpected outcomes of the ATBC and CARET trials [8,9]. 0003-9861/$ - see front matter Ó 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.abb.2007.06.034 * Corresponding author. E-mail address: Karin.wertz@dsm.com (K. Wertz). 1 Abbreviations used: bC, b-carotene; ECM, extracellular matrix; CS, cigarette smoke; TSP, total suspended particulates; HbCO, carboxyhe- moglobin; cRNA, complementary RNA; dscDNA, double-stranded cDNA; qRT-PCR, quantitative RT-PCR; RA, retinoic acid; CO, carbon monoxide; Cyp, cytochrome P450. www.elsevier.com/locate/yabbi Archives of Biochemistry and Biophysics 465 (2007) 336–346 ABB