OBJECTIVE: We aimed to investigate the regulatory effects of hemin and EGCG on colon carcinogenesis and the underlying mechanism of action.
METHODS: Hemin and EGCG were treated in Caco2 cells to perform the water-soluble tetrazolium salt-1 assay, lactate dehydrogenase release assay, reactive oxygen species (ROS) detection assay, real-time quantitative polymerase chain reaction and western blot. We investigated the regulatory effects of hemin and EGCG on an azoxymethane (AOM) and dextran sodium sulfate (DSS)-induced colon carcinogenesis mouse model.
RESULTS: In Caco2 cells, hemin increased cell proliferation and the expression of cell cycle regulatory proteins, and ROS levels. EGCG suppressed hemin-induced cell proliferation and cell cycle regulatory protein expression as well as mitochondrial ROS accumulation. Hemin increased nuclear factor erythroid-2-related factor 2 (Nrf2) expression, but decreased Keap1 expression. EGCG enhanced hemin-induced Nrf2 and antioxidant gene expression. Nrf2 inhibitor reversed EGCG reduced cell proliferation and cell cycle regulatory protein expression. In AOM/DSS mice, hemin treatment induced hyperplastic changes in colon tissues, inhibited by EGCG supplementation. EGCG reduced the hemin-induced numbers of total aberrant crypts and malondialdehyde concentration in the AOM/DSS model.
CONCLUSIONS: We demonstrated that EGCG reduced hemin-induced proliferation and colon carcinogenesis through Nrf2-inhibited mitochondrial ROS accumulation.
目的:我们旨在研究血红素和EGCG对结肠癌发生的调节作用及其潜在的作用机制。
方法:在Caco2细胞中处理Hemin和EGCG以进行水溶性四唑鎓盐-1测定,乳酸脱氢酶释放试验,活性氧(ROS)检测试验,实时定量聚合酶链反应和蛋白质印迹。我们研究了血红素和EGCG对偶氮甲烷(AOM)和葡聚糖硫酸钠(DSS)诱导的结肠癌发生小鼠模型的调节作用。
结果:在Caco2细胞中,血红素增加细胞增殖和细胞周期调节蛋白的表达,和ROS水平。EGCG抑制血红素诱导的细胞增殖和细胞周期调节蛋白表达以及线粒体ROS积累。Hemin增加了核因子-2相关因子2(Nrf2)的表达,但降低Keap1表达。EGCG增强血红素诱导的Nrf2和抗氧化基因表达。Nrf2抑制剂逆转EGCG降低细胞增殖和细胞周期调控蛋白表达。在AOM/DSS小鼠中,血红素治疗引起结肠组织增生改变,通过补充EGCG抑制。EGCG减少了AOM/DSS模型中血红素诱导的总异常隐窝数量和丙二醛浓度。
结论:我们证明了EGCG通过Nrf2抑制线粒体ROS积累减少了血红素诱导的增殖和结肠癌的发生。