中文摘要：

背景与目的：除草醚（nitrofen）是一种除草剂，已被广泛用于肺发育不良动物模型的制备。本研究旨在观察除草醚对体外培养的Ⅱ型肺上皮细胞增殖、凋亡活性的影响及其分子机制。材料与方法：分别用20、40、80μmol/L除草醚处理Ⅱ型肺上皮细胞A549后，采用MTT比色法、集落形成实验检测细胞增殖活性，western blot和实时RT-PCR检测增殖细胞核抗原（PCNA）的表达，TUNEL法及吖啶橙一溴化乙啶荧光染色法观测细胞凋亡情况，western blot检测凋亡相关基因表达。结果：与对照组比较，20、40、80μmol/L除草醚作用12-48h后，A549细胞增殖活性降低12．43％～71．73％（P〈0．01），克隆形成能力抑制79．2％（P〈0．01）；细胞内PCNA蛋白及mRNA表达水平显著降低，且呈时间和剂量依赖性（P〈0．01）；除草醚作用后部分A549细胞发生凋亡形态学改变，凋亡率为8．0％～22．5％（P〈0．01），且不受caspases抑制剂zVAD-fmk的影响，凋亡抑制基因Bcl-xL表达显著下调（P〈0．01）。结论：除草醚可能通过分别下调PCNA和Bcl-xL的表达抑制Ⅱ型肺上皮细胞增殖、诱导凋亡。

英文摘要：

BACKGROUND ＆ AIM： Nitrofen is a herbicide used to establish the pulmonary hypoplasia model. The current study was performed to explore the effects and mechanisms of nitrofen on proliferation and apoptosis of cultured type Ⅱ pneumocytes. MATERIALS AND METHOOS： Type Ⅱ pneumocytes A549 were treated with 20, 40 and 80 μmol/L of nitrofen. Cellular proliferation was measured by MTF colorimetry, colony formation assay. Western blot and real-time RT-PCR were performed to detect the PCNA expression. Apoptosis was assayed by TUNEL labeling and acridine orange-ethidium bromide staining. Expression of apoptosis-related genes was detected by western blot. RESULTS： Compared with controls, administration of 20,40 and 80 μmol/L nitrofen for 12-48 hrs resulted in 12.43%- 71.73% decrease in proliferation （P 〈0.01）, and 79.2% decrease in colony formation （P 〈0.01） of A549 cells. The PCNA protein and mRNA within nitrofen-treated cells were reduced in a time-and dose-dependent manner（P 〈 0.01） Partial nitrofen-treated A549 cells presented morphological changes of apoptosis, with apoptotic rates of 8.0%- 22.5% （P〈0.01）, which could not be abolished by the pan caspase inhibitor zVAD-fmk. The expression of anti-apoptotic Bcl-xL was significantly down-regulated （P 〈 0.01） . CONCLUSION： Nitrofen decreased proliferation of cultured type Ⅱ pneumocytes associated with down-regulation of PCNA, and induced apoptosis associated with suppressed Bcl-xL expression.