三氧化二砷对人结肠癌SW620细胞OCT4和FOXO3a因子表达影响的研究

Effect of arsenic trioxide on the expression of OCT4 and FOXO3a in colorectal cancer SW620 cells

目的研究已证实三氧化二砷(As2O3)可杀伤干细胞,最新研究表明大肠癌是一种干细胞起源的疾病。实验研究As2O3对于大肠癌干细胞因子的作用及相关机制。通过观察FOXO3a基因沉默和激动后,As2O3对人结肠癌SW620细胞FOXO3a和OCT4表达的影响,探究As2O3对OCT4表达影响是否通过FOXO3a途径。方法采用脂质体转染siRNA方法降低人结肠癌SW620细胞FOXO3a的表达,采用PI3K抑制剂LY294002提高FOXO3a的表达。给予As2O3作用后,RT-PCR方法检测FOXO3a和OCT4 mRNA的表达,Western blot方法检测FOXO3a和OCT4蛋白的表达。结果①As2O3增加SW620细胞中FOXO3a mRNA及蛋白的表达,同时降低OCT4 mRNA及蛋白表达(P﹤0.05);②FOXO3a siRNA处理后,FOXO3a mRNA及蛋白的表达明显降低,OCT4 mRNA及蛋白的表达增加。LY294002处理后,FOXO3a mRNA及蛋白的表达增加,OCT4 mRNA及蛋白的表达减少(P﹤0.05);③FOXO3a siRNA处理后,As2O3对FOXO3a和OCT4蛋白及mRNA表达无影响(P>0.05),LY294002处理后,As2O3对FOXO3a和OCT4蛋白及mRNA表达无影响(P>0.05)。结论 As2O3能下调人结肠癌SW620细胞OCT4因子表达,其机制可能与上调FOXO3a因子表达有关。

Objective The failure of current treatments for conlon cancer has recently been attributed to the existence of cancer stem cells （CSC） , which are difficult to be killed by drugs because of their chemoresistant properties as well as their ability to stimulate neoangiogenesis. The aim of the current study was to evaluate the antitumor efficacy of arsenic trioxide in vitro. The effect of arsenic trioxide （As203） on the expression of OCT4 （Octamer binding proteins） and FOXO3a in eolorectal cancer SW620 cells was investigated by FOXO3a gene silencing and exciting. Methods Human colorectal cancer SW620 cells were transfected with FOXO3a specific siRNA using liposome method and treated by PI3K inhibitor LY294002. The mRNA and protein expressions of OCT4 and FOXO3a in human coloreetal cancer SW620 cells were detected respectively by reverse transcription-polymerase chain reaction （RT-PCR） and Western blot. Results ①The mRNA and protein expressions of FOXO3a were increased in human eolorectal cancer SW620 cells treated by As203, while the expressions of OCT4 mRNA and protein were decreased （ P 〈 0.05 ）. ②The mRNA and pro- tein expressions of FOXO3a were obviously decreased after transfection of FOXO3a specific siRNA, whereas the OCT4 mRNA and pro- tein expressions were increased（ P 〈 0.05）. The FOXO3a expressions of LY294002 treatment, however, were exactly contrary to that of siRNA. ③When transfected with FOXO3a specific siRNA, As203 made no effect on the mRNA and protein expressions of OCT4（P 〉 0. 05 ）. While treated by LY294002, As203 decreased the OCT4 mRNA and protein expressions （ P 〈 0.05 ）. Conclusion As203 could decrease the expression of OCT4 in colorectal cancer SW620 cell and the underline mechanism may be associated with the upregulation of FOXO3a expression.