Colon carcinoma is one of the commonly tumors that threaten human beings as its highly morbidity and mortality.Recent evidences suggested that microRNA-21 (miR-21) played an important role in the development of colon carcinoma and might be a potential biological marker for the diagnosis and prognosis of colon carcinoma.However,the potential effect of miR-21 based therapeutic studies in colon carcinoma remains to be fully elucidated.Methods: In present study, we constructed an eukaryotic expression vector encoding antisense oligonucleotides against miR-21 (termed as p-miR-21-ASO) and the expression of miRNA-21 in human colon cancer was detected by Real-time PCR.To assess its possible effects on the proliferation and migration capacity of human colon carcinoma cells in vitro, CCK-8 assay, colony formation assay and cell invasion, as well as migration assay,were performed respectively.Moreover, PTEN, one of target molecules of miRNA-21 ,was analyzed by Western blot and Fluorescence activated cell sorter assay.Finally,the transduction of AKT and ERK pathways in human colon carcinoma cells was determined by Western blot.Results: We found that transiently transfection of p-miR-21-ASO could efficiently decrease the relative expression of miR-21 in human colon carcinoma HCT116 cells, accompanied by impaired proliferation and clone formation.Furthermore, we found that down-regulation of miR-21 also could significantly abrogate the invasion and migration capacity in vitro, as well as the expression of VEGF which is critical for the metastatic capacity of colon carcinoma cells.Mechanistic evidence showed that down-regulation of miR-21 increased the expression of its target molecule PTEN in HCT116 cells.Finally, we revealed that the expression level of both phosphor-ERK1/2 and phosphor-AKT also were altered.Conclusions : Therefore, our data suggested miR-21 ASO against miR-21 might be a useful strategy to alter the expression of miR-21 in colon carcinoma cells ,which was helpful for the development of miR-21-based therapeutic strategies against clinical colon carcinoma.