Bowes R C, Parrish A R, Steinberg M A, Willett K L, Zhao W, Savas U, Jefcoate C R, Safe S H, Ramos K S
Faculty of Toxicology, Department of Physiology and Pharmacology, College of Veterinary Medicine, Texas A&M University, College Station 77843, USA.
Biochem Pharmacol. 1996 Aug 23;52(4):587-95. doi: 10.1016/0006-2952(96)00310-3.
Recent studies in this laboratory have shown that benzo[a]pyrene (BaP) modulates growth factor-related gene expression and proliferation of renal glomerular mesangial cells (GMCs) in vitro. Because many of the toxic and biochemical effects of this polycyclic aromatic hydrocarbon are mediated through oxidative metabolism, the present studies were conducted to examine the patterns of cytochrome P450IA1 (CYP1A1) and P4501B1 (CYP1B1) inducibility in mesangial cells and the molecular consequences of this response. Exposure of cultured GMCs to BaP (30 microM) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, 10 nM) for 24 hr induced CYP1A1 mRNA levels, a response abolished by cotreatment with 10 microM cycloheximide. The pattern of hydrocarbon inducibility was atypical in that BaP was a more effective inducer of CYP1A1 gene expression than TCDD, and both hydrocarbons induced aryl hydrocarbon hydroxylase (AHH) activity, but not ethoxyresorufin-O-deethylase activity. Cotreatment with alpha-naphthoflavone (alpha NF, 1 microM) or ellipticine (ELLIP, 0.1 nM) only partially inhibited the induction of AHH activity by BaP (30 microM). BaP and TCDD also induced expression of the CYP1B1 protein and the pattern of induction was comparable to that observed for CYP1A1. Treatment of GMCs with 30 microM BaP was associated with the formation of eight DNA adducts, and their occurrence could be inhibited by pretreatment with alpha NF (1 microM), but not ELLIP (0.1 nM). These results demonstrate that CYP1A1 and CYP1B1-related activities are induced in GMCs by BaP and TCDD and this induction is associated with metabolism of BaP to reactive intermediates that bind covalently to DNA.
本实验室最近的研究表明，苯并[a]芘（BaP）在体外可调节肾小球系膜细胞（GMCs）中与生长因子相关的基因表达及细胞增殖。由于这种多环芳烃的许多毒性和生化效应是通过氧化代谢介导的，因此开展了本研究以检测系膜细胞中细胞色素P450IA1（CYP1A1）和P4501B1（CYP1B1）的诱导模式以及这种反应的分子后果。将培养的GMCs暴露于BaP（30微摩尔）或2,3,7,8 - 四氯二苯并 - p - 二恶英（TCDD，10纳摩尔）24小时可诱导CYP1A1 mRNA水平升高，用10微摩尔环己酰亚胺共同处理可消除该反应。烃诱导模式不典型，因为BaP比TCDD是更有效的CYP1A1基因表达诱导剂，且两种烃均可诱导芳烃羟化酶（AHH）活性，但不诱导乙氧基亚香豆素 - O - 脱乙基酶活性。用α - 萘黄酮（αNF，1微摩尔）或玫瑰树碱（ELLIP，0.1纳摩尔）共同处理仅部分抑制BaP（30微摩尔）诱导的AHH活性。BaP和TCDD还诱导CYP1B1蛋白表达，且诱导模式与CYP1A1观察到的模式相似。用30微摩尔BaP处理GMCs与形成8种DNA加合物有关，其形成可被αNF（1微摩尔）预处理抑制，但不能被ELLIP（0.1纳摩尔）抑制。这些结果表明，BaP和TCDD在GMCs中诱导CYP1A1和CYP1B1相关活性，且这种诱导与BaP代谢为与DNA共价结合的反应性中间体有关。
