ObjectiveTo study the mechanism of invasion of CD133 positive population in gallbladder cancer. MethodsThe invasive abilities of the CD133 positive cells and the CD133 negative cells were detected by Transwell.The CXCR4 mRNA and protein in the CD133 positive cells and the CD133 negative cells were detected by the semi-quanti-tative RT-PCR, Western blot method, and immunofluorescence, respectively.SDF-1αand AMD3100 were respectively used to stimulate/inhibit the GBC-SD cells.The invasive ability and the migration force were detected in the CD133 posi-tive cells and the CD133 negative cells.The expressions CD133 mRNA and protein of the GBC-SD cells were detected by semi-quantitative RT-PCR and Western blot method, respectively. Results①The number of invasion cells in the CD133 positive cells was significantly more than that in the CD133 negative cells (23.78±8.74 versus 6.56±3.09, P=0.000 7).②The fluorescent protein of CXCR4 in the CD133 positive cells was stronger than that in the CD133 negative cells.The expression of CXCR4 mRNA in the CD133 positive cells was significantly higher than that in the CD133 negative cells (0.642 4±0.020 4 versus 0.335 9±0.043 2, P=0.004).The expression of CXCR4 protein in the CD133 positive cells was significantly higher than that in the CD133 negative cells (0.765 0±0.106 6 versus 0.409 4±0.019 5, P=0.013).③In the CD133 positive cells, compared with the control group, the number of invasion cells was significantly increased in the SDF-1αgroup (62.89±15.27 versus 23.78±8.74, P=0.000 6) and decreased in the AMD3100 group (10.33±2.00 versus 23.78±8.74, P=0.000 2).In the CD133 negative cells, compared with the control group, the number of invasion cells was not significant change in the SDF-1αgroup (6.89±4.23 versus 6.59±3.09, P=0.41) and in the AMD3100 group (6.11±2.67 versus 6.59±3.09, P=0.38), respectively.④In the CD133 positive cells, compared with the control group, the number of migration cells was significantly increased in the SDF-1αgroup (74.56±15.80 versus 35.56±10.97, P=0.000 3) and decreased in the AMD3100 group (12.67±2.40 versus 35.56±10.97, P=0.000 2).In the CD133 negative cells, compared with the control group, the number of migration cells was not significant change in the SDF-1αgroup (9.78±2.04 versus 9.56±1.74, P=0.43) and in the AMD3100 group (9.54±1.74 versus 9.56±1.74, P=0.42).⑤In the GBC-SD cells, compared with the control group, the CD133 mRNA was significantly increased in the SDF-1αgroup (0.626 5±0.048 7 versus 0.450 0±0.024 3, P=0.004) and decreased in the AMD3100 group (0.359 3±0.047 3 versus 0.450 0±0.024 3, P=0.011);the CD133 protein was significantly increased in the SDF-1αgroup (0.508 9±0.020 7 versus 0.440 9±0.013 0, P=0.016) and decreased in the AMD3100 group (0.317 7±0.013 7 versus 0.440 9±0.013 0, P=0.004). ConclusionThe high invasion ability of CD133 positive population in gallbladder cancer might be due to the high expression of CXCR4.