低浓度p,p'-滴滴涕对大肠腺癌SW620细胞增殖和凋亡的影响

Effect of low concentrations of p,p '- dichlorodiphenyltrichloroethane on proliferation and apoptosis of colorectal adenocarcinoma SW620 cells

目的探讨低浓度p,p＇-滴滴涕暴露对大肠癌SW620细胞增殖和凋亡的影响及作用机制。方法用p,p＇-滴滴涕1×10-12~1×10-6mol·L-1作用于SW620细胞48和96 h后,采用MTT实验检测细胞存活率。用p,p＇-滴滴涕1×10-10,1×10-9和1×10-8mol·L-1处理SW620细胞96 h后,用流式细胞仪检测细胞周期和细胞凋亡率。Western蛋白质印迹法检测Wnt/β-连环蛋白信号通路成员β-连环蛋白、磷酸化β连环蛋白和磷酸化糖原合成酶激酶3β,下游靶蛋白c-Myc和细胞周期蛋白D1,以及凋亡相关蛋白Bcl-2、Bax、胱天蛋白酶原8和胱天蛋白酶原3表达水平。结果 p,p＇-滴滴涕1×10-12~1×10-7mol·L-1作用96 h,明显促进SW620细胞存活（P〈0.01）;p,p＇-滴滴涕1×10-10,1×10-9和1×10-8mol·L-1处理SW620细胞96 h,与对照组相比,G1期细胞百分率显著减少（P〈0.01）,S期细胞百分率显著增加（P〈0.01）,细胞凋亡率显著降低（P〈0.01）;Wnt/β-连环蛋白信号通路成员β-连环蛋白和磷酸化糖原合成酶激酶3β以及下游靶蛋白c-Myc和细胞周期蛋白D1水平显著升高（P〈0.01）,磷酸化β连环蛋白水平显著降低（P〈0.01）;凋亡相关蛋白Bcl-2、胱天蛋白酶原8和胱天蛋白酶原3表达显著升高（P〈0.01）,Bax表达和胱天蛋白酶3活性显著降低（P〈0.01）。结论低浓度p,p＇-滴滴涕可能通过激活Wnt/β-连环蛋白信号通路及影响凋亡相关蛋白表达,进而促进SW620细胞增殖,抑制SW620细胞凋亡。

OBJECTIVE To investigate the effect and mechanism of low concentrations of p,p′-dichlorodiphenyltrichloroethane （p,p′-DDT） on colorectal adenocarcinoma SW620 cell proliferation and apoptosis. METHODS SW620 cells were exposed to low concentrations of p, p′-DDT ranging from 1×10-12 to 1×10-6 mol.L-1 for 48 and 96 h. MTT assay was employed to examine the effect of p,p′-DDT on SW620 cell viability. Different cell stages of cycle and apoptosis rate were determined by flow cytometry after SW620 cells were exposed to 1×10-10 , 1×10-9 and 1×10-8 mol.L-1 for 96 h. Western blotting was used to determine the protein expression of Wnt/ β-catenin signaling components 〔β-catenin, phospho-β-catenin and phospho-glycogen synthase kinase （ GSK） 3β〕, their downstream target proteins （ c-Myc and cyclin D1）and apoptosis related proteins （Bcl-2, Bax, procaspase 8 and procaspase 3）. RESULTS The viability of colorectal adenocarcinoma SW620 cells was significantly increased after exposure to low concentrations of p,p′-DDT ranging from 1×10-12 to 1×10-7 mol.L-1 for 96 h. p,p′-DDT 1×10-10 , 1×10-9 and 1×10-8 mol.L-1 exposure led to a decreased percentage of SW620 cells in G1 stage（P〈0.01） along with an increased percentage of cells in S stage（P〈0.01）. Meanwhile, the apoptosis rate was signifi-cantly decreased compared with control group （ P 〈 0. 01）. Exposure to p, p′-DDT from 1 × 10-10 to 1×10-8 mol.L-1 induced upregulation of phospho-GSK3β （ Ser9）, β-catenin, c-Myc and cyclin D1 in SW620 cells（ P 〈0.01）. Moreover, apoptosis related proteins Bcl-2, procaspase 8 and procaspase 3 were unregulated（P〈0.01）, and Bax level and caspase 3 activity were decreased in p,p′-DDT-stimulated cells（P 〈 0.01）. CONCLUSION Low concentrations of p, p′-DDT exposure activates Wnt/ β-catenin signaling and affects apoptosis-related proteins, which may be involved in p,p′-DDT-induced cell prolifer-ation as well as suppression of cell apoptosis in SW620 cells.