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 (CoCl

2

) in the cu

lture medium. Quantitative real-time PCR and Western blotting were used to detect HIF-1α protein and miRNA-200b level in CoCl

2

-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 CoCl

2

-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 (P0.01)

whereas

miRNA-200b level was significantly lower (P0.01). HIF-1α mRNA level in colorectal cancer samples was negatively correlated with miRNA-200b level (r=-0.324

P0.05). HIF-1α protein level in CoCl

2

-induced Caco-2 cells was increased after exposure to CoCl

2

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 CoCl

2

-induced Caco-2 cells was negatively correlated with miRNA-200b level (r=-0.7422

P0.05).       Conclusion      HIF-1α takes part in epithelial-mesenchymal transition of colorectal cancer cells probably through suppressing the expression of miRNA-200b.