靶向Chk2逆转乳腺癌启动细胞化疗耐药的实验研究

Interference of Chk2 reverses chemo-resistance of breast cancer initiating cells

目的探讨化疗压力下,乳腺癌启动细胞DNA损伤修复的能力以及DNA损伤修复机制在乳腺癌启动细胞化疗耐药中的作用。方法获取乳腺癌细胞株MCF-7及其阿霉素耐药株AdrR/MCF-7,球囊培养检测乳腺癌细胞的自我更新功能,流式细胞技术检测CD44+/CD24-细胞和侧群细胞的比例,单细胞凝胶电泳实验检测DNA断裂程度。结果 AdrR/MCF-7的球囊形成率高于MCF-7([8.71±0.71)%vs(3.94±1.90)%,P<0.05];AdrR/MCF-7中高表达CD44+/CD24-([59.27±4.86)%vs(1.86±0.60)%,P<0.001],并含有更高比例的侧群细胞([8.43±1.82)%vs(0.20±0.10)%,P<0.01];AdrR/MCF-7比MCF-7能更加迅速地修复阿霉素引起的DNA损伤,拖尾消失(28.33±21.60vs315.00±24.54),且伴有Chk2的异常激活。干预Chk2的激活可以降低乳腺癌启动细胞的DNA损伤修复能力,凋亡细胞比例由(4.86±0.89)%增加至(19.17±0.70)%。结论乳腺癌启动细胞的化疗耐药性与DNA损伤修复能力增强有关,该功能与Chk2的异常激活相关。

Objective To find out the mechanism responsibles for the chemo-resistance of breast cancer initiating cells. Methods MCF-7 and Adriamycin-resistant MCF-7 （AdrR/MCF-7） were obtained. Mammospheres formation efficiency were caculated to evaluate self-renewal capacity. The proportion of CD44＋/CD24- cells and side-population was tested by FACS. The single cell gel electrophoresis（SCEG） was used to test the DNA damage. Results Compared with chemo-sensitive MCF-7, AdrR/MCF-7 enriched higher proportion of cancer initiating cells, repaired chemo-induced DNA damage more efficiently, which was associated with activation of Chk2. Interfering activation of Chk2 reduced the capacity of DNA damage repair of breast cancer cells and resensitized them to chemotherapy. Conclusions The chemo-resistance of breast cancer initiating cells is related to enhanced capacity of DNA damage repair, which is regulated by activation of Chk2.