P10.09.B Retroelement expression in glioma tumors exhibits subtype specific patterns

Abstract Background There are ~3 million transposable elements in the human genome constituting about 42% of all basepairs. Retroelements (REs) ~90% present genome. Active REs considered highly mutagenic and have been implicated multiple steps cancer development progression, as well neurologic diseases. RE activity has functional effects on genome, including maintenance centromere telomere integrity, deleterious gene expression. Previous studies shown that certain families (HERVK, L1, Alu) expressed gliomas, however, their specific role arbitrators oncogenesis or promoters innate anti-tumor immune response remains uncertain. Moreover, it a soluble form PD-L1 (sPD-L1) blocks its inhibitory is produced by exaptation an intronic endogenous retroelement (LINE-2A) encoding PD-L1, highlighting importance potential therapeutic targets. In this analysis we aim to identify unique patterns expression across major subtypes glioma. Material Methods We conducted differential 49 using RNA-seq data measured glioma tumors from The Cancer Genome Atlas (TCGA). counts were software REDiscoverTE. Pairwise comparisons between (defined WHO2021) done 625 tumor samples adjusting for age, sex race. Results 10 exhibited significantly different (false discovery rate, FDR, <0.05) at least one subtype. Alu(Fold change, FC=1.5), RNA(FC=11.3), PiggyBac(FC=1.6), rRNA(FC=5.23) Dong-R4(FC=1.8) overexpressed IDH-wildtype glioblastoma while Gypsy(FC=0.4) CRP1(FC=0.26) decreased scRNA (FC=2.7) IDH-mutant oligodendroglioma compared Dong-R4 (FC = 0.53) showed LTR (FC=2.02) tRNA-Deu (FC=1.46), increased diffuse astrocytomas IDH-mutant, 1p/19q-codeleted oligodendrogliomas Gypsy =0.41) Conclusion within gliomas subtype-specific patterns. While established dysregulated cancer, our first exploring wide range retroelements context Given important transcriptional control, genomic instability, chromosomal rearrangements, oncogenic activation, identification individual holds intrinsic value biomarkers immunotherapy