Characterization of clinical significance of PD-1/PD-Ls expression and methylation in patients with low grade glioma

Abstract

BackgroundImmune checkpoints play crucial roles in immune escape of cancer cells. However, the exact prognostic values of expression and methylation of programmed death 1 (PD-1), programmed death-ligand 1 (PD-L1) and PD-L2 in low-grade glioma (LGG) have not been defined yet. MethodsA total of 514 LGG samples from TCGA dataset containing both PD-1, PD-L1 and PD-L2 expression, DNA methylation, and survival data were enrolled into our study. The clinical significance of PD-1/PD-Ls expression and methylation in LGG were explored. Besides, the correlation between PD-1/PD-Ls expression and methylation with the infiltration levels of tumor-infiltrating immune cells (TIICs) was assessed. Moreover, GO enticement analysis of PD-1/PD-Ls co-expressed genes was performed as well. R 3.6.2 and GraphPad Prism 8 were applied as main tools for the statistical analysis and graphical exhibition. ResultsPD-1/PD-Ls had distinct co-expression patterns in LGG tissues. The expression and methylation status of PD-1/PD-Ls seemed to be various in different LGG subtypes. Besides, upregulated PD-1/PD-Ls expression and hypo-methylation of PD-1/PD-Ls were associated with worse survival in LGG patients. In addition, PD-1/PD-Ls expression was revealed to be positively associated with TIICs infiltration, while their methylation was negatively associated with TIICs infiltration. Moreover, the PD-1/PDLs correlated gene profiles screening and Gene Ontology (GO) enrichment analysis uncovered that PD-1/PDLs and their positively correlated gene mainly participated in immune response related biological processes. ConclusionsHigh expression and hypo-methylation of PD-1/PD-Ls significantly correlated with unfavorable survival in LGG patients, suggesting LGG patients may benefit from PD1/PD-Ls checkpoint inhibitors treatment.