中文摘要：

目的：探索Fas通路在结肠癌细胞中诱导上皮间质转化（epithelial-mesenchymal transition,EMT）的分子机制.方法：分别对结肠癌细胞SW480及DLD1予以低剂量FasL（12.5 ng/mL）处理.作用3d后分别提取实验组和对照组细胞的总蛋白、总RNA,并进行Western blot、RT-PCR检测,分析FasL作用下结肠癌细胞的上皮标记物、间质标记物以及EMT相关的转录因子的表达状况.在低剂量FasL作用3d后行免疫荧光检测,观察EMT相关转录因子在细胞内的分布情况.建立稳定敲除Snail及Twist的结肠癌细胞系,再予以低剂量FasL刺激,采用Western blot、RT-PCR检测是否发生EMT过程.对结肠癌细胞SW480予以低剂量FasL（12.5 ng/mL）处理后,通过Western blot检测实验组和对照组细胞ERK1/2通路及p38通路的激活状况.对SW480细胞进行信号通路抑制剂的预处理,再予以低剂量FasL刺激,采用Western blot、RT-PCR检测是否发生EMT过程,从而探索Fas通路诱导EMT的可能机制.结果：低剂量FasL可使结肠癌SW480和DLD1细胞的上皮标记物表达下调,间质标记物表达上调,EMT相关转录因子在细胞核周聚集,细胞发生梭形改变,提示发生EMT.而将结肠癌细胞的Snail或Twist基因敲除后,FasL的上述诱导作用明显减弱.低剂量FasL可激活结肠癌细胞的ERK1/2通路激活,而ERK抑制剂可减弱FasL诱导的EMT过程.结论：Fas通路可能通过激活ERK1/2通路诱导结肠癌细胞发生EMT.

英文摘要：

Objective：The present study aimed to examine the presence and mechanism of Fas-induced epithelial-mesenchymal transition （EMT） in human colon cancer cells. Methods：Colon cancer cells, namely, SW480 and DLD1, were treated with low-dose FasL （12.5 ng/mL） for 3 d. Total protein and total RNA levels of the experimental and control groups were extracted, and Western blot and RT-PCR were performed to measure both the transcriptional and translational levels of epithelial markers such as CDH1 and Villin, mesenchymal markers such as CHD2 and Vimentin, and EMT transcriptional factors such as Snail and Twist. Immunofluorescence was performed to observe the cellular distribution of EMT transcriptional factors on the third day of treatment. Snail and Twist stably knocked-down colon cancer cell lines were established and confirmed by Western blot. Colon cancer cells with low-expressing Snail or Twist were treated with low-dose FasL for 3 d. Western blot and RT-PCR were performed as described above to study the dependence of Fas-induced EMT on either Snail or Twist. Colon cancer cells, specifically SW480, were treated with low-dose FasL for 1 h, and Western blot was performed to test the activation status of the extra-cellular regulated protein kinases 1/2 （ERK1/2） pathway and the p38 pathway at 15 min, 30 min, and 1 h. SW480 was pretreated for 2 h with the signaling pathway inhibitor, which was demonstrated efficiently by Western blot, and then treated with low-dose FasL for 3 d. Western blot and RT-PCR were performed as described above to explore the possible mechanisms of Fas-induced EMT. Results：The transcriptional and translational levels of the epithelial markers decreased, whereas those of the mesenchymal markers and of the EMT transcriptional factors increased in colon cancer cells, namely, SW480 and DLD1, after treatment of low-dose FasL for 3 d. The resulting levels were accompanied by the nucleus translocation of EMT transcription factors and cellular morphological changes from paving-stone-like sh