缺氧下调结肠癌细胞株CDX2表达的研究

目的探讨缺氧诱导因子1α(HIF-1α)和基因系尾型同源盒基因2(CDX2)在人结肠癌细胞株SW480和LS174T不同缺氧时间的表达及其可能的作用机制。方法(1)MTT方法检测在不同CoCl2浓度(100,150,200μmol/L)下和不同时点(24,36,48 h)时对SW480和LS174T细胞活力以及增殖的影响,筛选适宜的CoCl2作用浓度。(2)在细胞化学缺氧培养相应时段,采用半定量RT-PCR技术检测HIF-1α,Snail和CDX2的mRNA的表达变化;同时采用Western blotting技术检测CDX2的蛋白表达。结果结肠癌细胞株在不同浓度CoCl2环境下随缺氧时间的延长,细胞活力明显受到抑制。在低浓度CoCl2(100μmol/L)干预下,随着缺氧时间的延长,HIF-1α和Snail mRNA表达逐渐上升,缺氧24 h时达到高峰,CDX2 mRNA及蛋白表达水平逐渐下降。结论缺氧诱导HIF-1α过表达可通过下调CDX2而加速结直肠癌的进展。

Hypoxia-induced expression of HIF-1&alpha|decreases CDX2 expression in human colorectal cancer cell lines

Objective：To investigate the mechanisms and relationship between HIF-1α and CDX2 expressions in human colonic cancer cell line SW480 and LS174T during different time of hypoxia.
Methods：(1)The two tumor cell lines (SW480 and LS174T) were respectively exposed to CoCl2 (100,150 and 200 μmol/L) for different time periods (24 h,36 h and 48 h), and cells viability and proliferation were detected by MTT methods in order to select suitable CoCl2 concentration. (2) Semiquantitative RT-PCR were used to detect the change in mRNA level of SW480 and LS174T under CoCl2 (100μmol/L). Total amounts of CDX2 protein in SW480 and LS174T were examined by Western blot.
Results：Higher concentrations of CoCl2 (150, 200μmol/L) significantly decreased cell survival rate (P＜ 0.05). So, we selected low concentration of CoCl2 (100μmol/L) to construct hypoxic model. HIF-1α mRNA expression of SW480 and LS174T increased with prolongation of hypoxia time when cells were exposed to CoCl2 (100μmol/L) and reached peak at 24 hours hypoxia (P＜0.05). Similar results were observed in Snail mRNA expression. But mRNA and protein expression of CDX2 reduced significantly under CoCl2 (100μmol/L) and gradually declined as the time of hypoxia was prolonged.
Conclusions：HIF-1α might be up-stream regulator of CDX2 and its over expression may play an important role in progression of colorectal cancer.