Pastorelli R, Guanci M, Cerri A, Negri E, La Vecchia C, Fumagalli F, Mezzetti M, Cappelli R, Panigalli T, Fanelli R, Airoldi L
Department of Environmental Health Sciences, Istituto di Ricerche Farmacologiche Mario Negri, Milan, Italy.
Cancer Epidemiol Biomarkers Prev. 1998 Aug;7(8):703-9.
The benzo(a)pyrene (BaP) metabolite benzo(a)pyrenediolepoxide (BPDE) is strongly implicated as a causative agent of lung cancer. To assess the risk of exposure to BaP, we made a combined analysis of levels of BPDE adducts to hemoglobin (Hb), serum albumin (SA), and lymphocyte DNA in 44 patients with incident lung cancer, as a prototype of a population mainly exposed to tobacco-derived BaP. We also investigated whether genetic polymorphisms of cytochrome P450IA1 (CYPIA1), microsomal epoxide hydrolase (mEH), and glutathione S-transferase M1 (GSTM1), which are involved in BaP metabolism, can be determinants of adduct formation. BPDE-Hb, BPDE-SA, and BPDE-DNA adducts were quantified as BaP tetrols released from hydrolysis of macromolecules and measured by high-resolution gas chromatography-negative ion chemical ionization-mass spectrometry to achieve high specificity and sensitivity. Individuals with detectable Hb adducts were positive for SA adducts but not vice versa, suggesting that BPDE-Hb adducts are less informative indicators of BaP exposure. Using PCR methods on DNA, we characterized GSTM1 deletion, CYPIA1 MspI and exon 7 valine variants, and mEH polymorphisms at amino acid positions 113 (EH3) and 139 (EH4). Levels of BPDE adducts were no different among CYPIA1, mEH, and GSTM1 genotypes. However, individuals with measurable BPDE-SA adducts were CYPIA1 variant carriers more frequently (P = 0.03). There was a slightly higher percentage of DNA detectable adducts in subjects with CYPIA1 exon 7 valine polymorphism. When subjects were classified by both polymorphisms on the mEH gene, those with two slow alleles (EH3 homozygous mutated) and no fast alleles (EH4 homozygous wild type) had a lower frequency of BPDE-SA adducts and no DNA adducts (P = 0.06). These results are based on a small number of observations thus far, but this exploratory study suggests that CYPIA1 and mEH variants might have an impact on BPDE exposure markers such as BPDE-SA adducts. Chemical specificity in adduct measurements is important to identify the biomarkers that reflect BaP exposure more accurately.
苯并(a)芘（BaP）代谢物苯并(a)芘二氢二醇环氧化物（BPDE）被强烈认为是肺癌的致病因素。为评估BaP暴露风险，我们对44例新发肺癌患者血红蛋白（Hb）、血清白蛋白（SA）及淋巴细胞DNA上BPDE加合物水平进行了综合分析，这些患者是主要暴露于烟草衍生BaP人群的一个典型代表。我们还研究了参与BaP代谢的细胞色素P450IA1（CYPIA1）、微粒体环氧化物水解酶（mEH）和谷胱甘肽S-转移酶M1（GSTM1）的基因多态性是否可作为加合物形成的决定因素。BPDE-Hb、BPDE-SA和BPDE-DNA加合物通过从大分子水解释放的BaP四醇进行定量，并通过高分辨率气相色谱-负离子化学电离-质谱法进行测量，以实现高特异性和高灵敏度。可检测到Hb加合物的个体SA加合物呈阳性，但反之则不然，这表明BPDE-Hb加合物作为BaP暴露的指标信息量较少。我们使用针对DNA的PCR方法，对GSTM1缺失、CYPIA1 MspI和外显子7缬氨酸变异以及mEH在氨基酸位置113（EH3）和139（EH4）的多态性进行了特征分析。CYPIA1、mEH和GSTM1基因型之间的BPDE加合物水平无差异。然而，可测量到BPDE-SA加合物的个体中CYPIA1变异携带者更为常见（P = 0.03）。CYPIA1外显子7缬氨酸多态性的受试者中可检测到DNA加合物的比例略高。当根据mEH基因的两种多态性对受试者进行分类时，具有两个慢等位基因（EH3纯合突变）且无快等位基因（EH4纯合野生型）的受试者BPDE-SA加合物频率较低且无DNA加合物（P = 0.06）。这些结果基于目前少量的观察，但这项探索性研究表明CYPIA1和mEH变异可能会对诸如BPDE-SA加合物等BPDE暴露标志物产生影响。加合物测量中的化学特异性对于更准确地识别反映BaP暴露的生物标志物很重要。
