Yin Huijuan, Ye Xuying, Niu Qing, Wang Chao, Li Yingxin
Laboratory of Laser Medicine, Institute of Biomedical Engineering, Chinese Academy of Medical Sciences, Tianjin, 300192, China.
Cardiovascular Department, Tianjin First Central Hospital, Tianjin, 300192, China.
Lasers Med Sci. 2016 Jul;31(5):817-24. doi: 10.1007/s10103-016-1887-x. Epub 2016 Feb 9.
Apoptosis is one of the major mechanisms of photodynamic therapy (PDT) that leads to tumor degradation. Apoptosis-related genes and proteins function in a certain order and timing in the complex network of apoptosis. To further understanding of the apoptotic mechanism of PDT, this research examined the time course of apoptosis from PsD007 (a second-generation photosensitizer developed in China) induced PDT on the rat acute myeloid leukemia cell line LT12. MTT was used to detect the temporal dynamic of PDT killing effects and identified the "apoptotic window" of 2-24 h. Apoptosis showed a basal peak at 2 h, and the duration of apoptosis depended on PDT dose, which disappeared quickly at low concentrations but lasted to higher levels to 6 or 12 h at high concentrations as detected by flow cytometry. High-content imaging confirmed these results. An 84-gene apoptosis PCR array identified 15 genes with an expression level change of over twofold at 6 h post-PDT. Nine apoptosis-related genes showed changes in expression at 2-12 h after PDT. TNF family genes TNF and FASLG showed a maximal change of 3.47- and 4.42-fold from baseline. Key apoptosis proteins such as activated caspases showed strong up-regulation after PDT, with the expression peaks of cleaved caspase-7, caspase-9 and PARP at 4-6 h, and cleaved caspase-3 delayed to 6-12 h. Our findings help clarify the time course of apoptosis events in response to PDT treatment in a leukemia cell line and may help contribute to the clinical application of PDT in leukemia treatment.
细胞凋亡是光动力疗法（PDT）导致肿瘤退化的主要机制之一。凋亡相关基因和蛋白在复杂的凋亡网络中按特定顺序和时间发挥作用。为了进一步了解PDT的凋亡机制，本研究检测了国产第二代光敏剂PsD007诱导的PDT对大鼠急性髓系白血病细胞系LT12凋亡的时间进程。采用MTT法检测PDT杀伤效应的时间动态，并确定了2-24小时的“凋亡窗口”。细胞凋亡在2小时出现一个基础峰值，凋亡持续时间取决于PDT剂量，低浓度时迅速消失，高浓度时持续到6或12小时更高水平，流式细胞术检测到这一结果。高内涵成像证实了这些结果。一个84基因的凋亡PCR阵列鉴定出15个在PDT后6小时表达水平变化超过两倍的基因。9个凋亡相关基因在PDT后2-12小时表达发生变化。TNF家族基因TNF和FASLG相对于基线的最大变化分别为3.47倍和4.42倍。关键的凋亡蛋白如活化的半胱天冬酶在PDT后表现出强烈上调，裂解的半胱天冬酶-7、半胱天冬酶-9和PARP的表达峰值在4-6小时，裂解的半胱天冬酶-3延迟到6-12小时。我们的研究结果有助于阐明白血病细胞系中对PDT治疗的凋亡事件的时间进程，并可能有助于推动PDT在白血病治疗中的临床应用。
