OBJECTIVE To investigate the effect of co-culture between colon cancer cells(SW1116)and human liver sinusoidal endothelial cells (HLSECs)on cancer cell metastasis, and to provide a novel model for studying the mechanism of colon cancer liver metastasis.METHODS HLSECs and SW1116 were co-cultured for 21 rounds in vitro. Transwell migration,gelatin-zymography,CCK-8 proliferation and colony formation assays were used to examine the invasion, proliferation, and colony forming ability of cancer cells.Assays were carried out to examine tumor growth ability and liver metastasis. The associated molecular change was examined by west blotting.RESULTS After 21 selection rounds, colon cancer cells SW1116P21 displayed a clear boundary. Compared with the SW1116 cells,SW1116P21 cells had a greater invasive ability, cell proliferation and colony formation in soft agar.A gelatin-zymography assay showed that the ability of SW1116P21 cells to secrete matrixmetaIloproteinase-2/9 was significantly greater than that ofSW1116 cells. Additionally, the capacity for subcutaneous tumorformation of SW1116P21 was significantly increased. It was found that mice injected with SW1116P21 cells developed significantly morevisually observable liver nodules than mice injected with SW1116cells.West blotting showed increased vimentin expression anddecreased E-cadherin expression in the SW1116P21 cells, comparedwith the SW1116 cells.CONCLUSION The interaction between SW1116 and HLSECs maypromote tumor cell invasion, proliferation and colony formation in vitro, and tumor formation and liver metastasis in vivo. Anepithelial-mesenchymal transition occurs in SW1116P21 cells, whichcontributes to the change in the characteristics of tumor cells.rn