乳腺癌干细胞放疗反应性和耐受机制的研究

The response of breast cancer stem cells to radiation and the resistant mechanism of radiotherapy

目的 探讨乳腺癌干细胞对放疗的反应性以及耐受机制.方法 从人乳腺癌细胞株MCF-7中分离出乳腺癌干细胞并在体外进行悬浮培养成为细胞微球,用克隆形成实验检测它们对放射治疗的反应性,荧光实时定量聚合酶链反应（Real time PCR）技术检测乳腺癌干细胞和非干细胞在辐射处理前后ATM、p53、Her-2、Ku70/Ku80和Survivin的基因表达.结果 悬浮培养的MCF-7细胞在2 Gy辐射下的平均存活分数（SF2）=0.49,单层培养的MCF-7细胞的SF2=0.27（P〈0.01）;悬浮培养的MCF-7细胞ATM、p53、Her-2、Ku70/Ku80和Survivin的基因表达量分别是单层培养的MCF-7细胞的（5.29±1.36）倍、（1.37±0.73）倍、（2.10±0.57）倍、（4.69±1.45）倍和（1.80±1.29）倍.结论 乳腺癌干细胞比乳腺癌非干细胞具有更强的辐射抗性,具有更强的DNA修复能力是乳腺癌干细胞重要的抗辐射耐受机制之一.

Objective To discuss the response of breast cancer stem cells to radiation and its resistant mechanism. Methods Single breast cancer stem cells were isolated from the human breast adenocarcinoma cell line, MCF-7, and suspension-cultured into mammary cell microspheres in vitro. The radiosensitivity of these breast cancer stem cells were evaluated using a colony formation assay. Real-time polymerase chain reaction （PCR） was used to detect the expression levels of the following genes before and after radiation in the breast cancer stem cells, along with non-stem cells of the breast cancer cell line： ATM, p53, Her-2, Ku70/Ku80 and Survivin. Results The average survival fraction （SF2） of the suspensioncultured MCF-7 cells after 2 Gy of radiation was 0. 49, while the average SF2 of MCF-7 cells cultured as a monolayer was 0. 27 （P〈0.01）. Compared to the MCF-7 cells grown in a monolayer, the suspension-cultured MCF-7 cells had higher expression levels of ATM, p53, Her-2, Ku70/Ku80 and Survivin; The expression of ATM, p53, Her-2, Ku70/Ku80 and Survivin was 5. 29±1. 36,1. 37±0. 73,2.10±0. 57,4. 69±1. 45,and 1. 80±1.29 fold, respectively. Conclusion Breast cancer stem cells have stronger anti-radiation capabilities than breast cancer non-stem cells. The stronger DNA repair capacity is an important resistant mechanism about radiotherapy of breast cancer stem cells.