ObjectiveTo detect the expressions of CD133 in four gastric cancer cell lines (KATO-Ⅲ, SGC7901, AGS, and MKN-45) and investigate the different biological characteristics of CD133 positive (CD133+) cells and CD133 negative (CD133-) cells in the KATO-Ⅲ cell lines. MethodsThe CD133 gene and protein expressions of four gastric cancer cell lines were evaluated by semiquantitative RT-PCR and Western blot, respectively. CD133+ cells in KATO-Ⅲ cell lines were isolated by magnetic activated cell sorting (MACS) and examined in morphology, growth characteristics, proliferation, and differentiation in vitro. The sensitivity of different concentrations (0.05, 0.10, 0.20, 0.50, and 1.00 mg/ml) 5-fluoropyrimidinedione (5-FU) were contrasted by drug sensitivity testing in vitro (Cell Counting Kit 8-assay) between CD133+ cells and CD133- cells. ResultsThe expressions of CD133 gene and protein in the KATO-Ⅲ cell lines were significantly higher than those in the other three cell lines (Plt;0.05). CD133+ cells produced spheroid colonies in serum-free medium culture and were ber abilities of proliferation and differentiation than those of CD133- cells in vitro. The inhibitor rate of the CD133+ cells at concentration of 0.50 mg/ml was lower than that of CD133- cells (Plt;0.05). ConclusionsCell population with CD133+ in the KATO-Ⅲ cell lines have b ability of cloning, better capability of proliferation and differentiation, as well as anticancer drug resistance to 5-FU. CD133 can be applied as one of surface markers for the detection to gastric cancer initiator cells.