TRPC6介导高级别胶质瘤低氧下的糖代谢改变与放疗增敏的机制研究

High grade glioma is the most frequent and malignant brain tumor in adults. Radiotherapy is one of the most important measures to glioma postoperative adjuvant therapy. Complications such as pseudoprogression and post-radiation temporal lobe necrosis are always due to radiation resistance, increasing sensitivity of radiotherapy is a key to improve the median survival time of patient after surgery. According to our pre-experiments: TRPC6 affected glucose uptake during hypoxia in a manner that was dependent on HIF accumulation and TRPC6 closely associated with the cell cycle G2/M and DNA replication. Although, the metabolic change of tumor and sensitivity of radiation is not fully understood. In this proposal, based on our pre-experiment, we plan to work on DNC6 and RNA interference to inhibit TRPC6 for further research to reveal if the change of glycolysis will produce a series of effects on tumor cells. In addition, we use micro-array and PCR to find the targeted gene to demonstrate the mechanism in multi-levels which including molecule, cells, animal mode and clinical research. The successful completion of the current study might provide some new potential targets for more effective treatment of high grade glioma.

高级别胶质瘤是常见的成人颅内恶性肿瘤，放疗是术后重要的辅助治疗措施。因放疗抵抗的存在，总体疗效不尽人意，还常出现假性进展、放射性脑坏死等并发症，所以增敏放疗是提高术后患者中位生存期的关键。本课题组通过前期实验发现：TRPC6可以通过HIF调节胶质瘤在低氧下的葡萄糖摄取，且TRPC6与细胞周期G2/M期和DNA复制关系密切，但涉及进一步糖代谢方式的改变对肿瘤生长和放疗敏感性的机制研究尚未见报道。本项目拟在预实验基础上，通过DNC6及siRNA阻断TRPC6，在胶质瘤细胞和动物模型中揭示糖代谢改变对肿瘤生长和对放疗敏感性的影响，再利用基因芯片筛选出下游“关键蛋白X”，在标本中通过PCR扩增得到相互印证，从分子、细胞、动物及临床多层次阐明其机制，为高级别胶质瘤的治疗及放疗增敏提供新的干预靶点。

众所周知，表观遗传修饰会极大地影响基因转录。然而，这些非特异性修饰如何转变为特异性基因表达很大程度上仍是未知的。在人类神经胶质瘤中由TRPC6调节的脯氨酸氧化酶（POX）1转录中，我们的研究发现p53介导的H3K9Me2脱甲基化作用为OIP5-AS1结合O位点提供了先决条件，并控制神经胶质瘤中POX转录。在POX启动和POX转录阶段的H3K9Me2脱甲基化必须有p53 / KIAA1718的复合物的存在。在POX启动子上发现了一个P位点，p53/KIAA1718复合物可与该位点的结合，对于POX启动子上H3K9Me2的还原、OIP5-AS1与O位点结合以及POX转录起到关键作用。.抑制TRPC6可通过POX抑制神经胶质瘤的生长。 我们的结果表明，p53/P位点对H3K9Me2的定向去甲基化作用和OIP5-AS1/O位点结合单元的形成，这两者都在TRPC6调节POX转录和胶质瘤生长过程中起到至关重要的作用。