AIM: To investigate the effect and mechanism of blockade of the CXC chemokine receptor-4 (CXCR4) signaling pathway by AMD3100, a small non-peptide CXCR4 inhibitor, on invasion and metastasis of colorectal cancer cells in vitro.METHODS: Human colorectal cancer cell line SW480 was treated with AMD3100 at different final concentrations.3-(4,5-dimethylthiazole-2-yl)-2.5-dipheny-ltetrazolium bromide (MTT) assay was used to detect the effect of AMD3100 on cell proliferation. The invasion ability of SW480 cells was determined by cell invasion assay kit.In the presence of AMD3100, the CXCL12-mediated migratory response of SW480 cells was tested by classical chemotaxis assays. RT-PCR analysis and Western blotting were used to detect the expression of vascular endothelial growth factor (VEGF), matrix metalloproteinase-2 (MMP-2)and -9 (MMP-9) in SW480 cells.RESULTS: Cell viability was significantly suppressed by AMD3100 in a dose-dependent manner. AMD3100 (100and 1000 ng/mL) significantly inhibited the invasion ability of SW480 cells. Treatment with AMD3100markedly reduced the expression of VEGF and MMP-9but not MMP-2 in SW480 cells.CONCLUSION: The CXCL12/CXCR4 system is an important mediator of proliferation and invasion of CXCR4-expressing colorectal cancer cells, AMD3100inhibited invasion and metastasis activity of the colorectal cancer cell line SW480 through down-regulation of VEGF and MMP-9 expression.