CLIC4 Is a New Biomarker for Glioma Prognosis.

BACKGROUND: Chloride Intracellular Channel 4 (CLIC4) plays a versatile role in cellular functions beyond its role in primary chloride ion transport. Notably, many studies found an association between CLIC4 expression and cancers. However, the correlation between CLIC4 and glioma remains to be uncovered. METHODS: A total of 3162 samples from nine public datasets were analyzed to reveal the relationship between CLIC4 expression and glioma malignancy or prognosis. Immunohistochemistry (IHC) staining was performed to examine the results in an in-house cohort. A nomogram model was constructed to predict the prognosis. Functional enrichment analysis was employed to find CLIC4-associated differentially expressed genes in glioma. Immune infiltration analysis, correlation analysis, and IHC staining were employed, aiming to examine the correlation between CLIC4 expression, immune cell infiltration, and ECM (extracellular matrix)-related genes. RESULTS: The expression level of CLIC4 was correlated with the malignancy of glioma and the prognosis of patients. More aggressive gliomas and mesenchymal GBM are associated with a high expression of CLIC4. Gliomas with IDH mutation or 1p19q codeletion express a low level of CLIC4, and a high expression of CLIC4 correlates with poor prognosis. The nomogram model shows a good predictive performance. The DEGs (differentially expressed genes) in gliomas with high and low CLIC4 expression are enriched in extracellular matrix and immune functions. On the one hand, gliomas with high CLIC4 expression have a greater presence of macrophages, neutrophils, and eosinophils; on the other hand, a high CLIC4 expression in gliomas is positively associated with ECM-related genes. CONCLUSIONS: Compared to glioma cells with low CLIC4 expression, gliomas with high CLIC4 expression exhibit greater malignancy and poorer prognosis. Our findings indicate that a high level of CLIC4 correlates with high expression of ECM-related genes and the infiltration of macrophages, neutrophils, and eosinophils within glioma tissues.