Aquaporin-4 and MicroRNA Expression in Meningiomas: A Tissue-Level Exploratory Analysis

Background: Meningiomas exhibit considerable biological heterogeneity that is not fully captured by histopathological grading. Tissue-based molecular markers may provide complementary insight into tumor biology within routine diagnostic settings. Methods: Formalin-fixed paraffin-embedded tissue samples from 65 intracranial meningiomas and 13 non-neoplastic controls were analyzed. Aquaporin-4 (AQP4) expression was assessed using immunohistochemistry, while miR-216a, miR-320a, and LINC00461 levels were quantified by means of RT-qPCR. Expression patterns were compared across groups and evaluated in relation to histological grade. Results: AQP4 expression was significantly reduced in meningiomas compared with controls and showed a further decrease in higher-grade tumors. Although expression of miR-216a and miR-320a was also lower in tumor samples, these differences did not reach statistical significance. Correlation analysis revealed modest but significant associations between AQP4 and miR-216a, as well as between miR-216a and miR-320a. Individual markers demonstrated limited discriminatory performance; however, combined expression patterns suggested underlying molecular variability across tumor grades. Conclusions: Our findings indicate that AQP4 downregulation represents a consistent feature in meningiomas, while associated microRNA alterations may reflect coordinated but context-dependent expression patterns. Although these markers are not sufficient as standalone diagnostic tools, their combined tissue-level assessment may provide complementary information on tumor heterogeneity. These findings should be interpreted as exploratory and highlight the need for further validation in larger and mechanistic studies.