Survivin-2B在硒诱导白血病细胞命运决定中的作用与机制

The complex relationship between apoptosis and autophagy is an important and attractive issue that is needed to be studied and resolved. In recent ten years, we explored the mechanisms by which selenite induced apoptosis and autophagy in leukemia cells and identified a series of molecules which was involved in these processes. In recent study, we discovered survivin-2B, one of survivin splicing variants, could promote autophagy in leukemia cells after selenite exposure. Selenite apparently down-regulated survivin-2B in P53 wildtype NB4 cells and further switched protective autophagy to apoptosis. However, in P53 deficient Jurkat cells, survivin-2B was not down-regulated and autophagy was promoted. This project aimed to investigate the mechanisms by which survivin-2B regulated apoptosis and autophagy in leukemia cells. This investigation will discuss the regulatory effects of P53-related pathway on the stability and expression of survivin-2B, identify the downstream molecules of survivin-2B and explore the pattern by which survivin-2B regulates autophagy and further determines cell fate. This project will provide theoretical support for the clinical application of selenite.

细胞自噬与凋亡信号通路之间复杂的网络调控关系是目前生物学的重点研究课题。近十年来，我实验室深入研究硒诱导白血病细胞凋亡和自噬的信号通路与机制。鉴定数个关键的节点蛋白。最近发现Survivin的一种剪接异构体Survivin-2B可促进白血病细胞自噬。硒可明显下调P53野生型NB4细胞的Survivin-2B，并促进NB4由自噬转向凋亡。而硒对P53缺失型Jurkat细胞的Survivin-2B无明显下调，但促进Jurkat的自噬性死亡。本项目将进一步分析Survivin-2B对白血病细胞自噬与凋亡的调控作用。探讨P53蛋白及相关通路对Survivin-2B的表达及稳定性的影响，鉴定与Survivin-2B相互作用的蛋白与自噬和凋亡相关的信号通路。揭示Survivin-2B在硒诱导白血病细胞命运决定中的作用和机制。并为阐明P53蛋白相关通路调控Survivin-2B功能的作用机制提供理论依据

本申请项目以亚硒酸钠为抗癌抗肿瘤药物，研究其作用下白血病细胞的死亡机理。一方面，我们探索无机硒处理NB4 细胞后survivin-2B，IKK alpha，P73 及UVRAG蛋白水平的变化趋势，确定这些蛋白本身对于细胞自噬和凋亡的调控方式以及这些蛋白之间的作用关系，通过探讨硒处理下NB4 细胞中自噬和凋亡的转化关系，揭示survivin-2B 及其相关通路在硒诱导NB4 细胞死亡中所发挥的作用。最后，通过构建NB4 细胞的异种移植瘤裸鼠模型，验证硒在体外的治疗效果及相关蛋白在体外的变化趋势。另一方面，实验室前期研究结果发现，清除硒作用下NB4 细胞中上升的活性氧可有效阻止硒所诱导的细胞凋亡，然而无机硒在其他白血病细胞中是否仍然存在潜在的治疗效果，尚缺实验进行论证。在本研究中，我们发现硒还可以通过抑制白血病HL60 细胞中微管的动态变化影响细胞周期进程，通过细胞周期激酶的活性变化调节凋亡相关分子，并最终诱导HL60 细胞凋亡，最后，在HL60 细胞的异种移植瘤模型中，我们同样在体内进一步验证硒的治疗效果、硒对于微管的抑制作用及其对于Mcl-1 和cyclin B1 的调控方式。