国外报道和我们前期工作证明miR-34家族在胶质瘤组织和肿瘤血管内皮细胞中低表达，发挥抑癌基因的作用。miR-34家族调节血肿瘤屏障(BTB)通透性和抑制肿瘤血管生长的效果及机制未见报道。通过系列前期研究提出了工作假说：在脑胶质瘤微血管内皮细胞中过表达miR-34家族成员miR-34a和miR-34c，可能分别通过负性调节转录因子MAZ和PKCε的表达增加BTB通透性；同时激活自噬反应抑制肿瘤血管生长。本项目拟先验证miR-34a和miR-34c分别与MAZ和PKCε的结合，明确结合位点；研究miR-34a和miR-34c通过调控MAZ基因表达影响BTB功能的机制；进一步研究miR-34a和miR-34c通过调控PKCε基因表达影响BTB功能、自噬反应和肿瘤血管生长的机制；最后明确miR-34a或miR-34c单独或联合应用的效果。研究结果能为增加化疗药物转运，提高脑胶质瘤疗效提供新途径。

Both foreign reports and our previous work proved the expression levels of miR-34 family are low in gliomas and tumor vascular endothelial cells, which acts as tumor suppressor genes to regulate the biological behavior of glioma. There has been no report about the effects of miR-34 family membranes on regulation of blood-tumor barrier (BTB) permeability and inhibition of tumor angiogenesis, as well as the related potential mechanisms. Using molecular biologic and bioinformatics methods, we proposed the following working hypothesis building on a series of our previous research (see the details in the working foundation): overexpression of miR-34a and miR-34c, the membranes of miR-34 family, in brain glioma vascular endothelial cells, might regulate the express of transcription factor MAZ negatively, resulting in reduction of the tight junction associated proteins claudin-5, occludin, ZO-1 and increase of BTB permeability. On the other hand, miR-34a and miR-34c might also change the express and distribution of tight junction associated proteins and cytoskeletal proteins by regulating the express of PKCε negatively, causing further increase of the BTB permeability. Meanwhile, overexpression of miR-34a and miR-34c in brain glioma vascular endothelial cells might also induce autophagy to inhibit tumor angiogenesis..On the basis of our previous work, this project will firstly verify the targeted binding and the binding sites between miR-34a and miR-34c and their target genes MAZ and PKCε. Then we will clarify the regulatory mechanisms of miR-34a and miR-34c on MAZ gene express, and prove the transcriptional regulatory mechanisms of MAZ on tight junction associated proteins as well as the effects on BTB function. Moreover, the regulatory mechanisms contributing to PKCε expression, BTB function, autophagy and tumor angiogenesis by miR-34a and miR-34c will be investigated. Finally, we will make a decision about the best choice between administration with miR-34a and miR-34c separately or in combination by analyzing the anti-tumor efficacy on glioma in nude rats with the association of carboplatin. This project could not only clarify the molecular mechanisms related to the regulation of BTB function and inhibition of tumor angiogenesis by miR-34a and miR-34c, but also provide a new pathway to strengthen the delivery of chemotherapeutic agents to neoplastic foci and enhance the therapeutic efficacy on brain gliomas.