中文摘要：

目的探究滴滴涕（DDT）对人结直肠腺癌上皮细胞（DLD1）上皮间充质转化的影响及机制。方法DLD1细胞用DDT 0.01,0.1,1.0,10.0和100.0 nmol·L^-1处理48 h后,倒置显微镜下观察细胞形态;实时荧光定量PCR法检测E-钙黏着蛋白、N-钙黏着蛋白、波形蛋白和锌指转录因子Snail1的mRNA表达。Western蛋白质印迹法检测信号转导和转录激活因子3（STAT3）信号通路主要蛋白STAT3和p-STAT3的蛋白水平。用STAT3抑制剂WP1066（5μmol·L^-1）处理,通过Western印迹法和实时荧光定量PCR法检测其对DDT诱导的STAT3/Snail1信号通路中p-STAT3、STAT3的蛋白水平和上皮间充质转化关键因子E-钙黏着蛋白、N-钙黏着蛋白、波形蛋白和锌指转录因子Snail1的mRNA水平的影响。结果与正常对照组相比,DLD1细胞在DDT处理48 h后,细胞形态由卵圆形逐渐变为长梭形,E-钙黏着蛋白mRNA相对表达显著降低（P〈0.01）,为正常对照组的（42.4±2.8）%。N-钙黏着蛋白和波形蛋白mRNA相对表达显著提高（P〈0.01）,为正常对照组的1.91±0.1倍和（1.5±0.2）倍。STAT3信号通路蛋白STAT3和p-STAT3蛋白表达均升高（P〈0.01）,为正常对照组的2.1和1.8倍。锌指转录因子Snail1的mRNA相对表达显著升高（P〈0.01）,是正常对照组的（1.5±0.1）倍。STAT3抑制剂WP1066 5μmol·L^-1处理后,锌指转录因子Snail1 mRNA的表达明显下调（P〈0.01）,为DDT 1.0 nmol·L^-1处理组的（56.3±0.9）%,同时抑制DDT诱导的E-钙黏着蛋白mRNA表达升高（P〈0.01）,为DDT 1.0 nmol·L^-1处理组的2.5±0.1倍,N-钙黏着蛋白和波形蛋白mRNA表达降低（P〈0.01）,分别为DDT 1.0 nmol·L^-1处理组的（50.2±2.9）%和（61.6±6.1）%。结论 DDT可能通过STAT3/Snail1信号通路改变上皮间充质转化子E-钙黏着蛋白、N-钙黏着蛋白和波形蛋白的表达,进而促进大肠癌细胞上皮间充质转化。

英文摘要：

OBJECTIVE To explore the effect of clofenotane（DDT） on epithelial-mesenchymal transition（EMT） and the relevant molecular mechanism in human colorectal cancer cells.METHODS Human colorectal cancer cells DLD1 were treated with DDT 0.01, 0.1, 1.0, 10.0 and 100.0 nmol·L^-1for48 h.Then, the morphology of DLD1 cells was observed.mRNA levels of E-cadherin, N-cadherin, vimentin and Snail1 were detected by real-time PCR.Protein expression of STAT3 signaling pathway of proteins STAT3 and p-STAT3 was detected by Western blotting.STAT3 inhibitor WP1006（5 μmol·L^-1） was added to determine its impact on DDT-induced alternation of STAT3/Snail1 signaling and EMT-related molecules.Protein expression of STAT3 and p-STAT3 was detected by Western blotting and mRNA levels of E-cadherin, N-cadherin, Vimentin and Snail1 were detected by real-time PCR.RESULTS DLD1 cell morphology was changed after exposure to DDT 0.01-100.0 nmol·L^-1.Meanwhile, real-time PCR showed that the mRNA level of E-cadherin was significantly decreased compared with normal cell control（P〈0.01）, which was 42.4±2.8% of that in the normal control group.The mRNA levels of N-cadherin, Vimentin and Snail1 were significantly increased（P〈0.01）, which were 1.91±0.1, 1.5±0.2 and 1.5±0.1 times that of the normal control group.DDT 0.1, 1.0 and 10.0 nmol·L^-1exposure induced up-regulation of STAT3 and p-STAT3 protein levels（P〈0.01）, which were 2.1 and 1.8 times that of the normal control group.The addition of STAT3 inhibitor WP1066（5 μmol·L^-1） prevented STAT3 from phosphorylation as well as the up-regulation of Snail1（P〈0.01）, which was（56.3±0.9）% that of the DDT 1.0 nmol·L^-1treatment group.Compared with DDT treatment alone, the mRNA levels of EMT-related molecules were remarkably reversed by WP1066（5 μmol·L^-1） co-treatment, increasing E-cadherin but decreasing N-cadherin and vimentin in DLD1 cells（P〈0.01）, which were 50.2±2.9% and 61.6±6.1% of those in the DDT 1.0 nmol·L^-1treatment group, respectivel