曲古霉素A增强肺癌细胞对放射线敏感性及机制

目的：探讨组蛋白去乙酰化酶抑制剂曲古霉素A（trichostatin A，TSA）增强人非小细胞肺癌（NscLc）A549对γ-射线敏感性作用及机制。方法：以TSA（0．51zM）预处理细胞18h，再以5Gyγ-射线照射细胞，24h后采用MTT法检测细胞存活率，AnnexinV—PI染色检测细胞凋亡，Westernblot法检测胞浆中和线粒体促凋亡蛋白Bax的表达，流式细胞仪检测细胞线粒体膜电位变化。结果-5Gyγ-射线照射可轻度降低细胞存活率，仅有少量细胞发生凋亡，以TSA预处理再以γ-射线处理细胞，细胞存活率显著下降，凋亡细胞明显增多，伴有线粒体膜电位下降，以及Bax蛋白的激活，表现在线粒体Bax表达较单纯照射组显著增高。结论：TSA通过促进Bax蛋白的活化激活线粒体凋亡途径，增强增强A549细胞对γ-射线的敏感性。

Trichostatin A Increases Radiosensitivity of Non-small Cell Lung Cancer A549 Cells

Objective： To investigate the activity oftrichostatin A （TSA）, one of the HDIs, on radiosensitize human non-small cell lung cancer （NSCLC） cell line A549 cells in vitro. Methods： A549 cells were exposed to γ-irradiation with or without TSA pre-treatment. MTT assay was performed to detect cell viability. Apoptosis was analyzed with Annexin V-PI staining by flow cytometry. The pro-apoptotic protein Bax expression in cytoplasm and mitochondria was detected by western blot. The changes of mitochondrial membrane potential （MMP） were measured by flow cytometry. Results： The pre-treatment with TSA 0.5p, M radiosensitized A549 cells to -y-irradiation （5Gy） significantly by decreasing cell viability. γ-irradiation or TSA alone only caused small amount of apoptotic cells, as indicated by Annexin V positive cells. However, TSA pre-treatment enhanced γ-irradiation-induced apoptosis significantly. In the combined treatment group, mitochondrial Bax expression was higher than that in the other groups, and which decreased MMP significantly compared with γ-irradiation （5Gy） or TSA alone. Conclusions： TSA has potential to act as radio-sensitizer in A549 cells through Bax activation and mitochondrial apoptotic pathway.