[Effect of CD133(+) cells on the radiosensitivity of rectal cancer cells].

OBJECTIVE:To investigate the effect of CD133(+) cells on radiosensitivity of rectal cancer cells. METHODS:In vitro experiments: CD133(+) cells were purified with Immunomagnetic beads from human rectal cancer cell line SW480 cells and annexin V/PI staining was used to determine apoptosis in CD133(+) and CD133(-) cells. In vivo experiments: Transplanted rectal tumor was established in 30 nude mice using primarily established SW480 cells. The tumor cells were divided into CD133-high and CD133-low groups based on the immunohistochemical staining of CD133 expression of the tumor cells. The tumor size after irradiation was recorded every three days. RESULTS:CD133(+) cells had a much lower percentage of apoptosis after radiation exposure compared with CD133(-) cells [(12.6 ± 3.2) % vs. (38.8 ± 6.7) %, P < 0.01]. In vivo experiment showed that the normalized tumor size of CD133-high group (3.00 ± 0.32) became significantly larger than that of the CD133-low group(2.55 ± 0.29) at the ninth day and this difference lasted until the observation end (P < 0.05). CONCLUSIONS:CD133(+) cells have a radioresistant effect on rectal cancer cells and may become a potential therapeutic target in the radiotherapy of rectal cancer.