Abstract: Objective: To investigate the miR-155 expressions in colon cancer tissue and cell strain,and its clinical significance.Methods: The expressions of miR-155 mRNA in 40 cases of colon cancer tissue and adjacent carcinoma tissues,and cell strains were detected using RT-qPCR,and the clinical pathological indicators were analyzed.The effects of the inhibiting miR-155 expression on the proliferation,colony-formation and apoptosis of colon cancer cells were analyzed.Results: The results of RT-qPCR showed that the miR-155 mRNA expression in colon cancer tissues was significantly higher than that in adjacent carcinoma tissues(P<0.01).The difference of the expression of miR-155 in different differentiated colon cancer cells was statistically significant(P<0.05),and the expression of miR-155 in low-differentiated colon cancer cells was higher than that in medium and high-differentiated colon cancer cells(P<0.05 to P<0.01).The abnormally high expression of miR-155 was related to the big tumor size,poor differentiation degree,lymph node metastasis and distant metastasis(P<0.05 to P<0.01),but which was not related to the age and gender(P>0.05).Inhibiting the expression of miR-155 could inhibit the cell proliferation and colony-formation of colon cancer cells.Conclusions: The miR-155 high expression in colon cancer tissues can be used as an effective predictor of malignant degree and lymph node metastasis.The miR-155 has a certain value in the clinical targeted therapy of colon cancer.