Piipari R, Savela K, Nurminen T, Hukkanen J, Raunio H, Hakkola J, Mäntylä T, Beaune P, Edwards R J, Boobis A R, Anttila S
Departments of Occupational Medicine, Industrial Hygiene and Toxicology, and Epidemiology and Biostatistics, Finnish Institute of Occupational Health, Helsinki, Finland.
Int J Cancer. 2000 Jun 1;86(5):610-6. doi: 10.1002/(sici)1097-0215(20000601)86:5<610::aid-ijc2>3.0.co;2-m.
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 (32)P-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 1.57/10(8) nucleotides) in samples from smokers compared with non-smokers (mean 0.42/10(8) 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.
香烟烟雾中致癌物代谢酶表达的变异性可能导致个体对肺癌发生的易感性。本研究旨在确定吸烟以及3种主要的细胞色素P450（CYP）酶，即CYP1A1、CYP1B1和CYP3A（它们可代谢多环芳烃（PAH））对31名吸烟者和16名非吸烟者支气管肺泡巨噬细胞（BAM）中PAH-DNA加合物形成的影响。通过免疫印迹法测定CYP蛋白水平，采用核酸酶P1增强的（32）P后标记法测定PAH-DNA加合物水平。通过逆转录聚合酶链反应（RT-PCR）对另外10个样本进行检测，以确认特定CYP形式的表达。在吸烟者和非吸烟者的大多数样本中均检测到CYP3A蛋白，通过RT-PCR检测到CYP3A5。活跃吸烟者中CYP3A的水平似乎低于已戒烟者（p = 0.10）或从不吸烟者（p = 0.02）。通过免疫印迹法或RT-PCR均未检测到CYP1A1。在大多数样本中，CYP1B1的表达较低或无法检测到。吸烟者样本中的PAH-DNA加合物水平（平均1.57/10（8）个核苷酸）高于非吸烟者（平均0.42/10（8）个核苷酸，p < 0.001），且加合物数量与每日吸烟量相关（回归分析，p < 0.001）。与CYP3A水平低的吸烟者样本相比，CYP3A水平高的吸烟者样本中检测到的加合物水平更高（回归分析，p = 0.002）。由于CYP3A5在肺上皮细胞和BAM中均大量存在，其与加合物形成的关联表明这种CYP形式可能在香烟烟雾前致癌物的激活中起重要作用。
