Musashi1基因表达对人结肠癌HCT116细胞的放射增敏作用及其机制

目的 研究沉默Musashi1对人结肠癌HCT116细胞放射敏感性的影响，为放射治疗提供新的增敏靶点。方法 用慢病毒载体建立Musashil（Msi1）低表达的稳转细胞株及阴性对照细胞株，将细胞分为沉默组、空白对照组和阴性对照组，通过克隆实验、流式细胞技术检测细胞凋亡及细胞周期，证实其放射敏感性。结果 成功构建了沉默Musashi1的HCT116细胞。沉默组的D₀、D_q、N、SF₂分别为1.55、0.88、1.76 Gy和0.43，空白对照组分别为2.17、1.51、2.01 Gy和0.64，阴性对照组分别为1.99、1.45、2.07 Gy和0.62。沉默组相对于空白对照组的放射增敏比为1.40，相对于阴性对照组的放射增敏比为1.28。8 Gy照射后24、48、72 h，沉默组凋亡比例始终高于阴性对照组和空白对照组（F=65.16，P<0.05），而阴性对照组和空白对照组之间差异无统计学意义（P>0.05）。12 Gy照射后48 h，沉默组细胞周期中G₂/M期比例较空白对照组和阴性对照组显著下降（F=65.398，P<0.05）。结论 降低Musashi1的表达对人结肠癌HCT116细胞有放射增敏作用，可能通过促进其凋亡，解除G₂/M期阻滞而发挥放射增敏作用，有望成为新的增敏靶点。

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, D_q, 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), but there was no statistically significant difference between control and NC (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.