Radiosensitization and its mechanism of down-regulation of Musashi1 in colon carcinoma cell line HCT116

Objective To disclose whether the down-regulation of Musashi1 gene can sensitize human colon carcinoma cell line HCT116 to radiation. Methods Lentviral vectors were used to knockdown the expression of Musashi1 gene in HCT116 cell line (HCT116-Musashi1) and its negative control (NC). Cell survival was measured by the colony formation assay, cell apoptosis and cell cycle distribution were measured by a flow cytometry. Results HCT116-Musashi1 silence and its negative control cells were established successfully. The result of cell survival assay showed that D0, Dq, N, SF2 were 1.55, 0.88, 1.76 Gy and 0.43 for the Musashil silence group, 2.17, 1.51, 2.01 Gy and 0.64 for control cells, and 1.99, 1.45, 2.07 Gy and 0.62 for siRN NC, respectively. The radiosensitivity of Musashi1 silence group was significantly higher than that of control and siRNA NC, and SER was 1.40 and 1.28 respectively. After 8 Gy irradiation, the apoptosis rate of silence group was always higher than other two groups at 24, 48, and 72 h after irradiation(F=65.16, P 0.05). After 12 Gy irradiation, the percentage of cells in G2/M phase decreased significantly in the silence group compared with control group and NC group(F=65.398, P<0.05). Conclusions Knockdown of Musashi1 in HCT116 cells increases the radiosensitivity through promoting cell apoptosis and reversing G2/M arrest, indicating that Musashi1 may be a new target of radiotherapy. Key words: Colon cancer; RNA interference; Musashi1; Radiation sensitivity; Apoptosis