Expression of CYP1A1, CYP1B1 and CYP3A, and polycyclic aromatic hydrocarbon-DNA adduct formation in bronchoalveolar macrophages of smokers and non-smokers

Abstract

Variability in the expression of enzymes metabolizing carcinogens derived from cigarette smoke may contribute to individual susceptibility to pulmonary carcinogenesis. This study was designed to determine the effects of smoking and 3 major cytochrome P450 (CYP) enzymes, i.e., CYP1A1, CYP1B1 and CYP3A, which metabolize polycyclic aromatic hydrocarbons (PAH) on PAH‐DNA adduct formation in the bronchoalveolar macrophages (BAM) of 31 smokers and 16 non‐smokers. CYP protein levels were determined by immunoblotting and PAH‐DNA adduct levels by the nuclease P1 enhanced 32P‐postlabeling method. The expression of specific CYP forms was confirmed by reverse transcriptase‐polymerase chain reaction (RT‐PCR) from 10 additional samples. CYP3A protein, CYP3A5 by RT‐PCR, was detected in the majority of samples from smokers and non‐smokers. The levels of CYP3A appeared to be lower in active smokers than in ex‐smokers (p = 0.10) or never smokers (p = 0.02). CYP1A1 was not detectable by either immunoblotting or RT‐PCR. The expression of CYP1B1 was low or undetectable in most samples. The PAH‐DNA adduct levels were higher (mean 1.57/108 nucleotides) in samples from smokers compared with non‐smokers (mean 0.42/108 nucleotides, p < 0.001) and the number of adducts correlated with the number of cigarettes smoked daily (regression analysis, p < 0.001). Higher levels of adducts were detected in samples from smokers with a high level of CYP3A compared with those with a low level (regression analysis, p = 0.002). As CYP3A5 is abundant in both lung epithelial cells and BAM, its association with adduct formation suggests that this CYP form may be important in the activation of cigarette smoke procarcinogens. Int. J. Cancer 86:610–616, 2000. © 2000 Wiley‐Liss, Inc.

Polycyclic aromatic hydrocarbon‐DNA adducts in liver tissues of hepatocellular carcinoma patients and controls

“…26 In bronchoalveolar macrophages from patients with a suspicion of lung cancer or parenchymal lung disease, elevated adducts were found in smokers using the 32 P-postlabeling method. 27 We did not find differences in mean relative nuclear staining intensity with smoking status in liver tumors and adjacent nontumor tissues. Our previous study in breast tumor tissues also found no significant differences in PAH-DNA adduct levels by cigarette smoking status.…”

CYP3A5*3Polymorphism and Its Clinical Implications and Pharmacokinetic Role

“…[42] Based on the assumption that the activated PAHs are associated with decreased lung function, for which CYP3A5 is one of the PHA-metabolizing enzymes, [43][44][45] Kaur-Knudsen et al studied whether CYP3A5*3 influences lung function and the risk of chronic obstructive pulmonary disease (COPD) in smokers. [46] However, no association could be identified in the study between CYP3A5*3 and decreased lung function or risk of COPD among those who have smoked.…”

Transcription Factor Binding to a Putative Double E-Box Motif Represses CYP3A4 Expression in Human Lung Cells

“…The CYP3A enzymes expressed in human lung are important determinants of pulmonary carcinogenesis caused by metabolism of several inhaled xenobiotic compounds (Piipari et al, 2000;Mollerup et al, 2001;Yeh et al, 2003). Other lung diseases cause significant morbidity and mortality, and specific P450 enzymes are at least partially responsible for these diseases (Ding and Kaminsky, 2003;Yeh et al, 2003).…”