HIF1a-Notch通路在缺氧诱导胶质瘤逆分化为肿瘤干样细胞中的作用及机制

Tumor stem cells (TSC) play an important role in the process of tumor invasion, metastasis and recurrence, and the increasing of TSC was thought to be self-renewal ability of themselves. Our previous research showed that CD133-/CD15- glioma cells acquired stem cell character when cultured in hypoxia condition. Combined with the literature, we presume that differentiated glioma cells could retrodifferiate into tumor stem cell-like cell with the condition of hypoxia .In present research, CD133-/ CD15- glioma stem cell will be sorted using immuno-magnetic beads combined with flow cytometry in vitro, and the change of CD133-/CD15- biological characteristics and the tumorigenicity would be observed through real-time quantitative PCR and in vivo imaging technology on culture cell and xenograft tumor animal models with hypoxia condition. At the same time, the role of HIF1α-Noth1 signal pathway in retrodifferiation of CD133-/CD15- glioma cells would be elucidated by alteration of biology characteristics through gene silencing and over-expression technology. This study will enhance the understanding of the mechanism of the enrichment of TSC in the hypoxic microenvironment, to provide a new target for the biological therapy of cancer.

肿瘤干(TSC)细胞在肿瘤侵袭转移与复发过程中发挥了重要作用，既往认为TSC数量增多主要是自我更新能力增强的结果。我们前期实验显示，CD133-/CD15-胶质瘤细胞在缺氧培养时可表现出"干细胞特性"，结合文献，我们推测，已分化胶质瘤细胞在缺氧诱导下可逆分化为肿瘤干细胞样细胞(TSCL)。本研究拟在免疫磁珠结合流式细胞仪分选出CD133-/CD15- 胶质瘤细胞的基础上，通过体外缺氧培养及移植瘤低氧饲养动物模型，采用定量PCR、活体成像等技术，体内外观察缺氧对CD133-/CD15-细胞生物学特性改变及成瘤能力等方面的影响，证实缺氧可诱导胶质瘤细胞逆分化为TSCL；同时应用基因沉默与过表达技术，观察HIF1a-Notch1通路对胶质瘤细胞生物学特性逆转的影响，阐明其在胶质瘤细胞逆分化过程中的关键调控作用。研究结果将深化缺氧微环境中肿瘤干细胞富集机制的认识，为肿瘤生物学治疗提供新的治疗靶点。

胶质瘤的标准治疗方式为外科手术联合放化疗。然而，由于胶质瘤侵袭性生长特点，手术往往不能完全切除肿瘤，从而残余部分肿瘤细胞。其中包括肿瘤干细胞及普通分化肿瘤细胞。胶质瘤复发既往认为是胶质瘤干细胞自我更新的结果，缺氧微环境促进这一进程。查阅文献发现既往研究忽视了缺氧对普通分化胶质瘤细胞的影响。综上，我们推测：术后残余的肿瘤细胞通过逆分化形成肿瘤干样细胞进而促进肿瘤复发。因此，我们通过分选CD133-CD15-NESTIN- 细胞并通过单细胞成球，相关蛋白检测以及在体研究等予以证明。结果提示缺氧环境可以促进单个胶质瘤细胞成球样生长，并高表达肿瘤干细胞标记蛋白，这一逆分化现象受HIF1α调控。该研究的证明为胶质瘤的发生发展及术后复发提供了新的模型，同时也为肿瘤治疗提供了新的思考方向及治疗靶点。