Tianjin Centers for Disease Control and Prevention, Tianjin, People's Republic of China.
Toxicol Sci. 2010 May;115(1):295-303. doi: 10.1093/toxsci/kfq046. Epub 2010 Feb 15.
Ethylbenzene is an important industrial chemical that has recently been classified as a possible human carcinogen (International Agency of Research on Cancer class 2B), but the available data do not support the genotoxic mechanism of ethylbenzene-induced tumors in kidney. We investigated the effects of ethylbenzene on renal ultrastructure and explored the nongenotoxic mechanism of mitochondria-mediated apoptosis pathway. Forty male Sprague-Dawley rats were used as a vivo model with ethylbenzene inhalation for 13 weeks, and the metabolites of ethylbenzene, mandelic acid (MA), and phenylglyoxylic acid (PGA) in urine were examined by high-performance liquid chromatography. Meanwhile, the ultrastructure of renal tubular epithelial cells was observed, and cell apoptosis was detected via terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay. Furthermore, we investigated the expression levels of messenger RNA (mRNA) and protein of bax, bcl-2, cytochrome c, caspase-9, and caspase-3 in rat kidney. With respect to levels of MA, PGA, and MA + PGA, a significant dose-dependent increase was observed in 4335 and 6500 mg/m(3) ethylbenzene-treated groups against the control group. The mitochondria of renal tubular epithelial cells became a compact and vacuolar structure in 6500 mg/m(3) ethylbenzene-treated group, and ethylbenzene induced a significant increase in the number of apoptotic cells as compared to the control group. In addition, enhanced mRNA and protein expression levels of all measured genes were observed in various ethylbenzene-treated groups except the decreased bcl-2 expression levels. Our results indicated that ethylbenzene may induce apoptosis of renal tubular epithelial cells via mitochondria-mediated apoptotic pathways. MA and PGA in urine might be a parameter of biological dose in vivo after ethylbenzene inhalation.
苯乙烯是一种重要的工业化学品，最近被归类为可能的人类致癌物（国际癌症研究机构 2B 类），但现有数据并不支持苯乙烯诱导肾脏肿瘤的遗传毒性机制。我们研究了苯乙烯对肾脏超微结构的影响，并探讨了线粒体介导的细胞凋亡途径的非遗传毒性机制。40 只雄性 Sprague-Dawley 大鼠作为体内模型，用苯乙烯吸入 13 周，用高效液相色谱法检测尿液中苯乙烯的代谢产物马尿酸（MA）和苯乙醛酸（PGA）。同时，观察肾小管上皮细胞的超微结构，通过末端脱氧核苷酸转移酶介导的 dUTP 缺口末端标记法检测细胞凋亡。此外，我们研究了大鼠肾脏 bax、bcl-2、细胞色素 c、caspase-9 和 caspase-3 的信使 RNA（mRNA）和蛋白表达水平。与 MA、PGA 和 MA+PGA 水平相比，4335 和 6500mg/m(3)苯乙烯处理组明显呈剂量依赖性增加，与对照组相比。6500mg/m(3)苯乙烯处理组肾小管上皮细胞的线粒体变得致密和空泡化，与对照组相比，苯乙烯诱导的凋亡细胞数量显著增加。此外，除 bcl-2 表达水平降低外，各苯乙烯处理组均观察到所有测定基因的 mRNA 和蛋白表达水平增强。我们的结果表明，苯乙烯可能通过线粒体介导的细胞凋亡途径诱导肾小管上皮细胞凋亡。尿液中的 MA 和 PGA 可能是苯乙烯吸入后体内生物剂量的一个参数。
