miR-15b and miR-21 as Circulating Biomarkers for Diagnosis of Glioma

Malignant gliomas are lethal primary intracranial tumors. To date, little information on therole of deregulated genes in gliomas have been identified. As the involvement of miRNAs in the carcinogenesisis well known, we carried out a pilot study to identify, as potential biomarkers, differentially expressedmicroRNAs in blood samples of patients affected by glioma. We studied the miRNAs’ expression,by means of microarray and Real-Time PCR, in 30 blood samples from glioma patients and in 82blood samples of patients suffering from: (a) various neurological disorders (n=30), (b) primary B-lymphoma of the CentralNervous System (PCNSL, n=36) and (c) secondary brain metastases (n=16). By quantitative real time reverse-transcriptasepolymerase chain reaction (qRT-PCR), we identified significantly increased levels of two candidate biomarkers, miR-15b andmiR-21, in blood of patients affected by gliomas. ROC analysis of miR-15b biomarker levels allowed to differentiate patientswith tumour from patients without glioma. Furthermore, combined expression analyses of miR15b and miR-21 distinguishedbetween patients with and without glioma (90% sensitivity and 100% specificity). In addition, a decrement in the expressionlevels of miR-16 characterized glioblastomas compared to low grade and anaplastic gliomas. In conclusion, this pilot studysuggest that it’s possible to identify the disease state by meaning miR-15b and miR-21 markers in blood, while miR-16 canbe used to distinguish glioblastoma from other grade gliomas. They can potentially be used as biomarkers for non-invasivediagnosis of gliomas; further studies are mandatory to confirm our preliminary findings.