Investigation of Glioblastoma Cell-Secreted microRNA Signatures and Their Functional Effects on Tumor Angiogenesis

Glioblastoma multiforme, which belongs to high-grade gliomas, is the most common and serious primary gliomas in adults. Malignant gliomas are highly mobile, invasive, and difficult to completely resect through surgery. Temozolomide, which is able to penetrate the blood-brain barrier, is the major chemotherapeutic drug in the clinical treatment of malignant gliomas. However, the drug resistance of temozolomide decreases the therapeutic effects on the patients. The course of temozolomide treatment will last a lifetime which may cause a financial burden. Therefore, it’s imperative to develop replacement therapeutic drugs. Angiogenesis plays a critical role in enhancing glioblastoma formation and metastasis. Entirely understanding the angiogenesis-related molecular mechanisms may improve the future drug development and clinical therapy of glioblastoma. MicroRNAs comprise a novel class of endogenous, small, non-coding RNAs. MicroRNAs control gene expressions by targeting their target genes for degradation and/or translational repression. Increasing evidences reported that circulating microRNAs, secreting into the blood, could be used as biomarkers for disease therapy or prediction. Similarly, few circulating microRNAs have recently been identified from blood samples of glioblastoma, like miR-128 and miR-21. However, the roles and functions of these microRNAs in glioblastoma formation are still unclear. Moreover, it’s also no studies to investigate the origin and gene-regulated mechanisms of circulating microRNAs. The overall specific aims are to better characterize whether the glioblastoma cells could regulate the functions of vessel endothelial cell in tumor angiogenesis via secreting circulating microRNAs. We will also evaluate whether these microRNAs could be used as novel therapeutic targets for glioblastoma. In this proposal, we will use the high-throughput sequencing analysis to comprehensively investigate the circulating microRNA signatures from glioblastoma cells. The microRNA-regulated gene networks in vessel endothelial cells will also be investigated. Then, we will identify the candidate circulating microRNA which could enter into the endothelial cell and enhance the angiogenesis development by using co-culture system. We will explore the types of secretion vesicles to understand the delivery mechanism of circulating microRNA. Several well-established growth factors will be used to find the regulated mechanisms of circulating microRNA gene. To further understand the effect of microRNA on gene regulation, we will identify the novel target genes by using 3’ or 5’ UTR reporter assay. Finally, the single or combined treatment with clinical drugs, including temozolomide, bevacizumab and cilengitide, of LNA-microRNAs will be used to test the suppressive and synergistic effects on glioblastoma development by using xenograft animal models. The present proposal is an innovative study in researching glioblastoma cells-secreted circulating microRNA functions and regulations in glioblastoma development. The results will not only provide a better insight to cell-to-cell communications between glioblastoma cells and vessel endothelial cell resulting in tumor angiogenesis, but also clarify new functions and roles of circulating microRNA in disease formation. It will also provide a novel strategy for development of new chemotherapeutic combination of microRNAs and drugs clinically. We expect this new way can raise the survival rate of the patients with brain tumor.