Background and Objective:Chemotherapy is the main treatment for colon cancer,while multidrugresistance is the main reason for chemotherapy failure and tumor relapse.This study was to establish two oxaliplatinresistant colon cancer cell lines and evaluate their biological characteristics.Met hods:Oxaliplatin-resistant colon cancer cell lines SW620/L-OHP and lovo/L-OHP were established in vitro by continuous exposure to oxaliplatin(L-OHP) of low and gradually increased concentration.Growth curve,cross-resistance and resistance index of the oxaliplatin-resistant cell lines to various anti-cancer agents were determined by CCK8 assay.The expressions of P-glycoprotein(P-gp),multidrugresistance protein 1(MRP1) and MRP2 were detected by Western blot.Cell cycle distribution as well as the expression of CD133 and CD44 were measured by flow cytometry.Result s:It took 10 months to establish the SW620/L-OHP and LoVo/L-OHP cell lines with stable resistance to oxaliplatin.Cross-resistance to 5-fluorouracil,etoposide,cisplatin,vincristine and epirubicin but not to paclitaxel was observed.Longer doubling time,higher proportion of cells in G0/G1 phase and lower proportion in G2/M phase were observed in the two oxaliplatin-resistant cell lines compared with their parental cell lines.The expression of MRP2 in the oxaliplatin-resistant cells was up-regulated,while those of P-gp and MRP1 had no significant change.CD133 was overexpressed while CD44 level remained unchanged in SW620/L-OHP and LoVo/L-OHP cells.Conclusions:SW620/L-OHP and LoVo/L-OHP cell lines show a typical and stably resistant phenotype and may be used as research models. Background and Objective: Chemotherapy is the primary treatment for colon cancer, while multidrugresistance is the main reason for chemotherapy failure and tumor relapse. This study was to establish two oxaliplatinresistant colon cancer cell lines and evaluate their biological characteristics. Met hods: Oxaliplatin-resistant colon cancer cell lines SW620 / L-OHP and lovo / L-OHP were established in vitro by continuous exposure to oxaliplatin (L-OHP) of low and gradually increased concentration. Growth curves, cross-resistance and resistance index of the oxaliplatin-resistant cell lines to various anti-cancer agents were determined by CCK8 assay. The expressions of P-glycoprotein (P-gp), multidrug resistance protein 1 (MRP1) and MRP2 were detected by Western blot. Cell cycle distribution as well as the expression of CD133 and CD44 were measured by flow cytometry. Result s: It took 10 months to establish the SW620 / L-OHP and LoVo / L-OHP cell lines with stable resistance to oxaliplatin. Cross-resistance to 5-fluoro uracil, etoposide, cisplatin, vincristine and epirubicin but not to paclitaxel was observed. Longer doubling time, higher proportion of cells in G0 / G1 phase and lower proportion in G2 / M phase were observed in the two oxaliplatin-resistant cell lines compared with their parental cell lines. The expression of MRP2 in the oxaliplatin-resistant cells was up-regulated, while those with P-gp and MRP1 had no significant change. CD133 was overexpressed while CD44 level unchanged in SW620 / L-OHP and LoVo / L -OHP cells. Conclusion: SW620 / L-OHP and LoVo / L-OHP cell lines show a typical and stably resistant phenotype and may be used as research models.