TMIC-05. AGING-SPECIFIC MICRORNA EXPRESSION SIGNATURE IN ELDERLY GLIOBLASTOMA

Abstract PURPOSE The rise in aging population worldwide is increasing death from cancer, including glioblastoma. MicroRNAs (miRNAs/miRs) are small non-coding RNAs that mediate the posttranscriptional silencing of specific target mRNAs and that are currently recognized as important regulators of tumorigenesis and development. Here, we explore the impact of brain aging and aging-specific miRNAs on elderly glioblastomas. METHODS We comprehensively analyzed miRNAs expression using the TCGA dataset and identified miRNAs that are specifically expressed in elderly glioblastomas. To create the Ehime Glioma Genome Atlas (EGGA), RNA sequencing was performed using tumor tissues from 8 glioblastoma patients (4 elderly and 4 non-elderly). First, we evaluated the impact of the identified miRNAs on prognosis using TCGA and CGGA datasets and searched for target genes of specific miRNAs using TargetScan. The expression patterns of the identified target genes were verified using EGGA, TCGA, and CGGA datasets. RESULTS We divided the TCGA dataset into elderly and non-elderly groups based on three ages (75 years-old, 70 years-old, and 65 years-old) and analyzed the expression of miRNAs in tumor tissues. There were 3 miRNAs that showed abnormalities (1 increased miRNA, 2 decreased miRNAs), and among these, miR-210 (increased expression) and miR-507 (increased expression) were identified as miRNAs related to prognosis. Next, we analyzed the expression of EGGA and identified 410 mRNAs (368 increased mRNAs, 42 decreased mRNAs) that showed significantly abnormal expression in the elderly group. The target genes searched using TargetScan were 4,048 genes for miR-210 and 4,704 genes for miR-507. When compared with the 410 genes identified using EGGA, PLA2G3, a target gene to miR-507, was identified. The expression of PLA2G3 was also specifically increased in elderly glioblastoma in the TCGA dataset, and it had a strong influence on prognosis. CONCLUSION Our results found an aging-specific miRNA “miR-507” and its target gene “PLA2G3” that suggested as potential new therapeutic target molecules for improving the prognosis of elderly glioblastomas.