Evaluation of miR-497 & miR-219 as non-invasive biomarkers for meningioma and glioma

Introduction: The current WHO classification aids in predicting meningioma and glioma recurrence and prognosis. However, there is a dearth of circulating biomarkers with clinical value for meningioma diagnosis and classification. Circulating miRNAs have shown potential as cancer biomarkers in various tumours. This study evaluated specific miRNAs, miR-497 and miR-219, as convenient and efficient predictors of meningioma and glioma grades. MiR-497 was selected based on preliminary results from Professor Hannemane's group, indicating its potential as a meningioma biomarker. MiR-219 was chosen because of its reported differential expression according to meningioma grade. Methods: Serum and exosomal levels of miR-497 were studied in 74 meningioma samples (WHO grade I = 25, grade II = 25, and grade III = 24), 51 glioma samples (low-grade glioma = 25, GBM = 26), and 53 healthy control samples. The serum level of miR-219 was studied in 56 meningioma samples (grade I = 22, grade II = 14, and grade III = 20). Additionally, the relationship between miR-497 and miR-219 expression and DNA methylation status was investigated in 20 meningioma samples using qPCR for miRNA quantification. We tested two different normalisers, endogenous and external, evaluating their impact on the diagnostic value of miR-497. Results: Serum and exosomal levels of miR-497 effectively distinguished meningioma from control samples and were suitable identifiers for meningioma grade. When miR-497 and miR-219 were combined, the efficacy of the combined biomarker surpassed that of either miR-497 or miR-219 alone in meningioma classification. Both miR-497 and miR-219 exhibited significant changes in relation to the methylation status of meningioma. Conclusion: This study demonstrates that serum miR-497 serves as a potential, easily measurable biomarker for meningioma diagnosis and classification. Combining miR-497 and miR-219 enhances the accuracy of meningioma classification. Additionally, this is the first study to evaluate the correlation between serum circulating miRNA and methylation status in meningioma