NFAT1在多形性胶质母细胞瘤坏死形成中的作用及机制研究

Glioblastoma multiforme (GBM) is the most malignant primary brain tumor, and patients confront an extremely poor clinical outcome. Among the histological hallmarks of GBM, necrosis has been demonstrated to be a powerful predictor of poor patient prognosis. Although hypoxia and the expression of Hypoxia-induced Factor-1 (HIF-1) and Tumor Necrosis Factor-α (TNF-α) have been reported to play a role in the formation of necrosis, the mechanism of the development of necrosis in GBM remains unclear. In our previous studies, we found that the expression and activity of the nuclear factor of activated T cells-1 (NFAT1) are significantly up-regulated in GBMs. Importantly, activation-induced cell-death-like phenomena can occur in GBM cells when NFAT1 are over-activated. It has been reported that hypoxia could increase NFAT1 activation in GBM cells. Moreover, as a transcriptional factor, NFAT1 can regulate the expression of HIF-1 and TNF-α. In addition, under certain circumstances NFAT1 can induce necrosis. Therefore, we speculate that under hypoxic condition, by interaction with HIF-1 and TNF-α, NFAT1 may participate in the necrosis formation of GBMs. In the present study, using the stable transfection method to regulate the activity of NFAT1 and by the establishment of animal model in combination with in vitro experiments, we aimed to investigate the role of NFAT1 in the necrosis formation of GBM and the related molecular mechanism, which would contribute to the understanding of the mechanism of GBM malignant progression. The results of the study would provide new molecular targets for the treatment of GBM.

多形性胶质母细胞瘤（GBM）是最常见的原发性中枢神经系统恶性肿瘤，预后差。坏死形成是GBM的重要组织学特征，坏死的出现及其严重程度可以预测GBM的不良预后，但坏死形成的机制尚未明确。我们前期实验证实，活化T细胞核因子1（NFAT1）在GBM中的表达显著升高，当处于普通活化状态时，其促进细胞侵袭；而当NFAT1过度激活时，则通过“活化诱导的细胞死亡”样作用导致细胞死亡。GBM组织中存在引起NFAT1过激活的因素，如局部低氧等，结合文献报道NFAT1对坏死的调控,我们推测，在局部低氧环境下，NFAT1可能通过与HIF-1、TNF-α协同作用，诱导GBM坏死形成。本研究旨在通过调控肿瘤中NFAT1的表达及活性，建立动物模型，结合体外实验，探讨NFAT1在GBM坏死形成中的作用及分子机制，进而完善GBM恶性进展的内在机制，为GBM靶向治疗提供新的靶点，为诱导GBM由坏死向凋亡转化提供新的思路。

胶质母细胞瘤（GBM）是最常见的原发性中枢神经系统恶性肿瘤，预后差。坏死形成是GBM的重要组织病理学特征，mesenchymal分子亚型的GBM坏死形成最为显著，恶性程度最高。坏死的出现及其严重程度和GBM的不良预后相关，但坏死形成的机制尚未明确。我们前期实验证实，活化T细胞核因子1（NFAT1）在GBM中的表达显著升高，当处于普通活化状态时，其促进细胞侵袭；而当NFAT1过度激活时，则通过“活化诱导的细胞死亡”样作用导致细胞死亡。在本项目研究中，我们主要探讨了在肿瘤微环境影响下，NFAT1在GBM坏死形成中的作用及分子机制。本研究结果显示，（1）低氧环境能够活化integrin β1/NFAT1信号通路，进而调控HIF1-α，MMP-7, MMP-9及Cox-2表达，影响GBM细胞在体内及体外的侵袭和生长；（2）NFAT1表达和mesenchymal分子亚型显著相关，低氧环境通过活化NFAT1通路，影响炎症细胞因子表达，促进GBM细胞mesenchymal转化及坏死形成；（3）NFAT1通过调控IL6/IL6R信号通路的活性，促进GBM的增殖、侵袭及生长；（4）在TP53野生型GBM细胞中，锂剂联合替莫唑胺能够激活NFAT1，进而上调FasL表达，诱导肿瘤细胞死亡; （5）免疫相关微环境因素，包括肿瘤浸润免疫细胞的成分和比例，对胶质瘤的预后及生物学行为产生重要影响。我们的研究结果提示，在低氧微环境下，NFAT1信号通路异常活化。一方面上调侵袭相关基因的表达，促进GBM细胞的迁移和生长；另一方面活化IL6、TGF-β1，TNF-α等炎症通路，促进GBM细胞mesenchymal转化，同时促进肿瘤坏死形成。我们的研究结果强调了免疫炎症通路在GBM坏死形成及恶性进展中的重要作用，锁定NFAT1、integrin β1及IL6R为GBM治疗的重要靶点，为GBM治疗提供了新的思路和方向，为胶质瘤的预后评估提供了新的模型和方法。