P01.01 The role of exosome miRNA between tumor cells and microglias during the progression of medulloblastoma

Abstract

Abstract BACKGROUND Medulloblastoma (MB) is the most common malignant paediatric brain tumor. Recent studies show that M2 cells were relative more abundant in Shh subtype of MBs compared with other three subtypes. It’s known that M2 cells have close relationship with many tumors’ progression. But if they play any role in the progression of Shh subtype of MB is not yet clear. Many studies demonstrate that exosomes carring miRNAs have close relationship with tumor invasion. The aim of present study is to clarify the role of exosome miRNA between tumor cells and microglias during the progression of Shh subtype of medulloblastoma. MATERIAL AND METHODS Immunofluerescence staining using iNOS and Arg1, which is M1 and M2 specific marker, respectively, was performed in four subtypes of MBs. After coculture of exosomes extracted from Shh subtype of MB cell (DAOY) with microglia cell (BV2), Q-PCR and ELISA assay were done to evaluate the polarization status of the microglia. Transwell and scratch assay were then performed to detect the migration ability of DAOY cell after treatment of exosomes from polirized M2 cells. MiRNA sequencing by Ion Proton technology was then done to analyze the miRNAs expression level between Shh subtype and other subtype of MBs. Transformation assay was used to overexpress and inhibit the expression of these miRNAs respectively to further clarify the role of exosome miRNA in the polarization of BV2 cells. RESULTS M2 cells were observed more abundant than other three subtypes of tumors, supporting that M2 cells play some role in this subtype of MBs. Exosomes of DAOY cells can induce the polarization of M2 cells. The polarized M2 cells can improved the migration and invasion ability of DAOY cell. Dozens of miRNAs were identified with different expression level between Shh subtype of MBs and other subtype of MB cells. Among them, 4 miRNAs were reported to be related with polariztion of M2 in many other lesions. Three of the 4 miRNAs can induce the polarization of M2 in present study. CONCLUSION Our study demonstrated exosome miRNA play a critical role between tumor cells and microglias during the progression of Shh subtype of medulloblastoma.