Induction of highly proliferative phenotypes in cultured glomerular mesangial cells by benzo[a]pyrene alone or in combination with methoxamine.

Induction of highly proliferative phenotypes in cultured glomerular mesangial cells by benzo[a]pyrene alone or in combination with methoxamine.

Recent studies have suggested that aromatic hydrocarbons can initiate glomerular mesangial cell (GMC) injury and contribute to the onset of renal disease. The present studies were conducted to assess the impact of benzo[a]pyrene (BaP), a ubiquitous polycyclic aromatic hydrocarbon, on the proliferation of GMCs. Challenge of cultured GMCs with BaP (0.3-30 microM) for 24 h was associated with concentration-dependent decreases in DNA synthesis, a response mediated by selective interference with early G1 cell cycle progression. One cycle of sequential treatment with 3 microM BaP for 24 h followed by challenge with 10 microM methoxamine (MeoA), a growth-promoting alpha 1-adrenergic agonist, for an additional 24 h attenuated the inhibitory response elicited by BaP alone. Following three rounds of sequential treatment with BaP and MeoA, GMCs exposed to BaP alone or BaP/MeoA exhibited enhanced proliferation rates relative to controls. BaP/MeoA cells acquired the greatest proliferative enhancement and exhibited unregulated c-jun and c-fos gene expression under growth-arrested and serum-stimulated conditions. Marked increases in specific AP-1 binding to a synthetic oligonucleotide were observed upon serum stimulation of quiescent cultures of BaP/MeoA cells relative to controls or any of the other treatment groups. These data demonstrate that sequential treatment with BaP in combination with MeoA is associated with induction of highly proliferative phenotypes in GMCs characterized by differential expression of growth-related protooncogenes.

近期研究表明，芳香烃可引发肾小球系膜细胞（GMC）损伤，并促使肾脏疾病发病。本研究旨在评估苯并[a]芘（BaP）——一种普遍存在的多环芳香烃，对肾小球系膜细胞增殖的影响。用浓度为0.3 - 30微摩尔的BaP刺激培养的肾小球系膜细胞24小时，会导致DNA合成呈浓度依赖性降低，这种反应是通过选择性干扰G1早期细胞周期进程来介导的。先用3微摩尔BaP处理24小时，接着再用10微摩尔甲氧胺（MeoA，一种促进生长的α1 - 肾上腺素能激动剂）刺激24小时，这样一个周期的顺序处理会减弱单独用BaP所引起的抑制反应。经过三轮BaP和MeoA的顺序处理后，单独暴露于BaP或BaP/MeoA的肾小球系膜细胞相对于对照组显示出增殖速率提高。BaP/MeoA细胞获得了最大的增殖增强，并且在生长停滞和血清刺激条件下呈现出c - jun和c - fos基因表达失调。相对于对照组或任何其他处理组，在血清刺激BaP/MeoA细胞的静止培养物时，观察到特异性AP - 1与合成寡核苷酸的结合显著增加。这些数据表明，BaP与MeoA联合顺序处理与肾小球系膜细胞中高度增殖表型的诱导有关，其特征是生长相关原癌基因的差异表达。