人脑胶质瘤干／祖细胞系SU-2放射耐受及其相关机制的初步研究

目的研究胶质瘤干细胞在胶质瘤耐受放射中的作用,为克服恶性胶质瘤放射耐受寻找新的干预靶点。方法干细胞培养条件下培养自建人脑胶质瘤干/祖细胞系SU-2,以及人脑胶质瘤细胞系U251和SHG-44,观察不同剂量直线加速器照射前后细胞形态变化、Hoechst 33342-细胞和CD133 细胞比例、肿瘤细胞存活率和裸小鼠致瘤率等项指标,并以实时荧光定量PCR方法检测人脑胶质瘤细胞系U251和人脑胶质瘤干/祖细胞系SU-2照射前后MGMT基因表达水平。结果当照射剂量为1～15Gy时,人脑胶质瘤干/祖细胞系SU-2中的Hoechst 33342-细胞和CD133 细胞比例明显增加,高达18.73%和13.70%,细胞存活率升高、致瘤率(8/8)增加、侵袭性增强,MGMT基因表达水平轻度升高。结论经一定剂量的X线照射后,胶质瘤干细胞因具有强于其他肿瘤细胞的放射耐受性而出现选择性存活且细胞比例升高,其生物学特性如细胞存活率、体内致瘤率增加,侵袭性增强。可能与胶质瘤干细胞DNA损伤修复能力提高有关,确切的分子学机制值得进一步深入研究。

Preliminary study on radioresistance and relevant mechanisms of human cerebral glioma stem/pro-genitor cell line SU-2

Objective To investigate the effect of glioma stem cells in the radioresistance of glioma,and find out potential targets for overcoming radioresistance of malignant glioma. Methods Human cerebral glioma stem/progenitor cell line SU-2 and human cerebral glioma cell line U251,SHG-44 were cultured in vitro under stem cell culture conditions. Changes of cell morphology,percentage of Hoechst 33342- and CD133 cells,tumor cell survival ratio,nude mice tumorigeinity were observed before and after different radiation dosages of linear accelerator. MGMT gene expression levels of human cerebral glioma cell line U251 and human cerebral glioma stem/progenitor cell line SU-2 were assayed by real-time fluorescene quantitative PCR method before and after radiation. Results Over a range of 1-15 Gy radiation,percentage of Hoechst 33342- and CD133 cells in human cerebral glioma stem/progenitor cell line SU-2 obviously increased to 18.73% and 13.70%,respectively after radiation. Cell survival ratio increased,the tumorigeneity increased to 100% (8/8),invasiveness enhanced,MGMT gene expression level also increased after radiation. Conclusion Glioma stem cells enriched not only in numbers after radiation,their biological characteristics,such as survival ratio,tumorigeneity,invasiveness also increased. Upregulation of DNA repair capacity in radiated glioma stem cells maybe involved with radioresistance. Precise molecular mechanism should be further studied.