+ colon cancer cells show higher migratory capacity than CD133
- cancer cells in vivo. (A) To assess the tumorigenic capacity of the four phenotypic subpopulations, cells were injected subcutaneously into nude mice. At 30 days post-injection, mice were killed and xenografts excised for evaluation. A representative photograph of four mice from four groups is shown in the upper panel. The tumorigenesis data from all groups are shown in the lower panel. Data represent the mean ± SD of tumor weight. (B) Standard tail vein metastatic assays were used to confirm that CD133+CXCR4+ cells were responsible for metastatic cancer formation. Four phenotypic subpopulations isolated from HCT116 cells were injected into the tail veins of nude mice. After 120 days, the mice were sacrificed, and livers and lungs were harvested to observe metastatic tumor formation. A representative photograph of harvested lungs from the four groups is shown in the upper panel, with corresponding hematoxylin and eosin staining of metastatic lung tumor tissue. Arrows indicate metastatic lung nodules. The metastatic status of four groups is shown in the lower table. Comparisons between each group were made by Fisher's exact test or Student's t-test (*P <0.05 compared with the CD133+CXCR4- group).