GCT-72. ANALYSIS OF microRNA EXPRESSION PROFILE OF INTRACRANIAL GERM CELL TUMORS: A PROMISING TOOL FOR DIFFERENTIAL DIAGNOSIS

INTRODUCTION: One of the major limitations of pathological diagnosis for intracranial germ cell tumors (iGCTs) is tumor heterogeneity, which cannot be evaluated using limited amount of tumor tissues. In this study, we performed comprehensive analysis of microRNA (miRNA) of iGCTs to identify miRNAs profile to help determine tumor diagnosis. METHODS: RNA was extracted from frozen samples of 16 germinoma and 14 NGGCTs. Five non-iGCT pediatric brain tumor tissues were used as control. miRNA expression analysis was performed using a 3D-Gene Human miRNA Oligo Chip ver.22 (Toray Industries, Inc) which was designed to detect 2565 miRNAs. The miRNA expression profile was analyzed using t-SNE dimensionality reduction and weighted average difference method (WAD). RESULTS: Different histological subtypes of the iGCTs and control samples were clustered into distinct classes. Furthermore, we found that the germinoma, NGGCTs and control samples may be readily distinguished by expression patterns of miR-200 and miR-371a-3p: a high expression of miR-200 was observed in the NGGCTs, whereas a high expression of miR-371a-3p was observed in all cases of germinoma and some of NGGCTs. Neither of miR-200 nor miR371-3p was highly expressed in control samples. CONCLUSION: Our data indicated that germ cell tumor and other pediatric brain tumors, and also germinoma and NGGCT can be distinguished by expression patterns of 2 micro RNA, miR-200 and miR-371a-3p. These 2 microRNA may serve as a useful tool for supporting the pathological diagnosis of iGCTs.