Lu K P, Hallberg L M, Tomlinson J, Ramos K S
Department of Physiology and Pharmacology, College of Veterinary Medicine, Center for Environmental and Rural Health, Texas A & M University, College Station, TX 77843-4466, USA.
Mutat Res. 2000 Nov 6;454(1-2):35-44. doi: 10.1016/s0027-5107(00)00095-6.
Benzo(a)pyrene (BaP) modulates vascular smooth muscle cells (vSMCs) from a quiescent to proliferative phenotype, a shift associated with activation of L1Md retrotransposon [K.P. Lu, K.S. Ramos, Biochem. Biophys. Res. Commun. 253 (1998) 828-833]. The present studies were conducted to evaluate L1Md activation profiles in murine vSMCs treated with BaP or its oxidative metabolites, and to screen for possible insertional mutations into p53 and retinoblastoma (RB) genes. We also sought to examine the profile of DNA damage and repair in BaP-treated vSMCs. Northern analysis revealed that BaP (0. 03-3microM), and its major reactive 7,8-diol metabolite (0. 03-3microM), activate L1Md gene in a concentration-dependent manner. Two other metabolites, 3-OH BaP and 3,6-BaP quinone (0.03-3microM), as well as hydrogen peroxide (25-75microM) also activated L1Md. No insertional mutations into either p53 or RB genes were observed in vSMCs treated with BaP in vitro, although a slight elevation of p53 mRNA was observed as early as 4h after chemical challenge. Treatment of vSMCs with 3 or 30microM BaP for 4h increased unscheduled DNA synthesis (UDS) 1.4- and 2.5-fold, respectively. Challenge with 0. 3microM BaP for 24h inhibited DNA repair capacity in vSMCs for up to 48h. These results demonstrate that BaP and its oxidative metabolites activate L1Md retrotransposon in vSMCs, which coupled to DNA damage and inhibition of DNA repair are part of the atherogenic response elicited by BaP and related hydrocarbons.
苯并(a)芘（BaP）可使血管平滑肌细胞（vSMC）从静止表型转变为增殖表型，这种转变与L1Md逆转座子的激活有关[K.P. Lu，K.S. Ramos，《生物化学与生物物理研究通讯》253（1998）828 - 833]。本研究旨在评估用BaP或其氧化代谢产物处理的小鼠vSMC中L1Md的激活情况，并筛选p53和视网膜母细胞瘤（RB）基因可能的插入突变。我们还试图检测经BaP处理的vSMC中的DNA损伤和修复情况。Northern分析显示，BaP（0.03 - 3μM）及其主要活性7,8 - 二醇代谢产物（0.03 - 3μM）以浓度依赖性方式激活L1Md基因。另外两种代谢产物，3 - OH BaP和3,6 - BaP醌（0.03 - 3μM）以及过氧化氢（25 - 75μM）也激活了L1Md。体外经BaP处理的vSMC中未观察到p53或RB基因的插入突变，尽管在化学刺激后4小时就观察到p53 mRNA略有升高。用3或30μM BaP处理vSMC 4小时分别使非预定DNA合成（UDS）增加了1.4倍和2.5倍。用0.3μM BaP刺激24小时可使vSMC的DNA修复能力在长达48小时内受到抑制。这些结果表明，BaP及其氧化代谢产物可激活vSMC中的L1Md逆转座子，这与DNA损伤和DNA修复抑制相关，是BaP和相关碳氢化合物引发的动脉粥样硬化反应的一部分。
