结直肠癌及缺氧的结直肠癌细胞中HIF-1α与miRNA-200b表达的相关性

Correlation of HIF-1α and miRNA-200b expression in human colorectal cancer tissues and hypoxia-induced colorectal cancer cells

目的探讨缺氧诱导因子HIF-1α与miRNA-200b在结直肠癌及缺氧的结直肠癌细胞中的表达以及两者的相关性。方法采用实时定量PCR检测50例结直肠癌患者的结直肠癌组织及其癌旁组织中HIF-1α与miRNA-200b的表达。利用Co Cl_2构建结肠癌细胞系的缺氧诱导模型,通过实时定量PCR和Western blot分别测定缺氧的Caco-2细胞中HIF-1α和miRNA-200b基因表达并确立两者相关性。结果 HIF-1α在癌组织中的表达显著高于癌旁组织（P〈0.01）,miRNA-200b在癌组织中的表达显著低于癌旁组织（P〈0.01）,且HIF-1α和miRNA-200b在癌组织中的表达呈负相关（r=-0.324,P〈0.05）。缺氧处理2 h后,HIF-1α表达升高,miRNA-200b表达降低;随着缺氧时间延长（4~12 h）HIF-1α表达逐渐降低,miRNA-200b的表达缓慢上升;缺氧16 h,HIF-1α的表达回升且达到另一个高峰,miRNA-200b的表达降至最低。Real-time PCR和Western blot联合检测发现,HIF-1α和miRNA-200b表达呈相反的趋势。结论 HIF-1α可能通过抑制miRNA-200b的表达从而参与结直肠癌上皮细胞EMT的过程。

Objective To determine the expression of HIF-1α and miRNA-200b in human colorectal cancer tissues and hypoxia-induced colorectal cancer cells and determine their correlation. Methods The expression of HIF-1α mRNA and miRNA-200b in 50 colorectal cancer samples and their pericancerous mucosa were detected by quantitative real-time PCR. The cell hypoxia model was established by use of cobalt chloride （CoCl2） in the culture medium. Quantitative real-time PCR and Western blotting were used to detect HIF-1α protein and miRNA-200b level in CoCl2-induced Caco-2 cells. The correlations between HIF-1α mRNA level and miRNA-200b level in human colorectal cancer tissues and between HIF-1α protein level and miRNA-200b level in CoCl2-induced Caco-2 cells were analyzed by Spearman’s rank correlation test. Results HIF-1α mRNA level in colorectal cancer samples was significantly higher than that in the pericancerous mucosa （P〈0.01）, whereas, miRNA-200b level was significantly lower （P〈0.01）. HIF-1α mRNA level in colorectal cancer samples was negatively correlated with miRNA-200b level （r=-0.324, P〈0.05）. HIF-1α protein level in CoCl2-induced Caco-2 cells was increased after exposure to CoCl2 for 2 h, and miRNA-200b level was decreased in 2-h hypoxia. In hypoxia for 4 to 12 h, HIF-1α protein was decreased slowly, whereas miRNA-200b level was increased. Finally, HIF-1α was rapidly increased to the peak after 16-h hypoxia, and on the contrary, miRNA-200b level was decreased rapidly to the lowest level. HIF-1α protein level in CoCl2-induced Caco-2 cells was negatively correlated with miRNA-200b level （r=-0.7422, P〈0.05）. Conclusion HIF-1α takes part in epithelial-mesenchymal transition of colorectal cancer cells probably through suppressing the expression of miRNA-200b.