Aquaporin-4 as a New Potential Molecular Biomarker for Prognosis of Low-Grade Glioma: Comprehensive Analysis Based on Online Platforms

AQP4 is a significant factor in the transcellular and transepithelial water movement and its abnormal expression has been detected in many types of tumors. The purpose of this study is to explore its role in lower-grade gliomas (LGG) using freely available online bioinformatics tools.OncoLnc database was utilized to analyze the Cox coefficients and compare AQP4 expression between various types of tumors; TIMER database and Gene Expression Profiling Interactive Analysis were used to compare gene expression between LGG and normal tissues; UCSC Xena browser generated Kaplan-Meier survival curves in TCGA-LGG and subgroups; LinkedOmics database screened the most relevant genes based on Pearson's correlation coefficient; Gene Ontology Biological Process and Kyoto Encyclopedia of Genes and Genomes enrichment analysis were performed through gene set enrichment analysis to explore possible molecular mechanisms.LGG had higher AQP4 expression compared to normal tissues and ranked first among 21 different types of cancer (P<0.05). The oligodendroglioma group had the lowest AQP4 expression and the longest overall survival (P<0.05). LGG with astrocytoma, IDH mutation, or 1p19q co-deletion had lower AQP4 expression and longer overall survival (P<0.001). LGG with lower AQP4 expression, without 1p19q co-deletion, without chemotherapy, and with or without radiation therapy had longer overall survival (P<0.05). AQP4 and co-expressed genes were involved in complex biological processes in LGG, including regulation of neurotransmitter level, PPAR signaling pathway, cell adhesion molecules, and others.AQP4 is a prognostic marker in LGG and its subgroups, and those with lower AQP4 expression may have longer overall survival.