MicroRNA-profiling of miR-371~373- and miR-302/367-clusters in Serum and Cerebrospinal Fluid Identify Patients with Intracranial Germ Cell Tumors

Abstract Purpose: Intracranial germ cell tumors (iGCT) comprise germinoma and non-germinoma. Their diagnosis predominantly relies on biopsy as only one-fifth of patients present with elevated biomarkers (AFP/ß-HCG) in serum or cerebrospinal fluid (CSF). MicroRNAs (miR/miRNA) have emerged as non-invasive biomarkers in extracranial GCT and may potentially facilitate non-invasive diagnosis in iGCT. Methods: We analyzed eight miRNAs in serum and CSF from the miR-371~373- and miR-302/367-clusters and four miRNAs differentially expressed in iGCT tissue (miR-142-5p/miR-146a-5p/miR-335-5p/miR-654-3p) from eight iGCT patients (age 10-33 years) and 12 control subjects by pre-amplified RT-qPCR. MiR-30b-5p (serum) and miR-204-5p (CSF) acted as reference genes. ΔCt-values were expressed as 2-ΔΔCt after standardization against controls. Results: Between iGCT and control patients’ serum ΔCt-values of miR-371a-3p (p=0.0159), miR-372-3p (p=0.0010), miR-367 (p=0.0190), miR-302a (p=0.0381) and miR-302d-3p (p=0.0159) differed significantly. Discriminatory pattern in CSF was similar to serum as miR-371a (p=0.0286), miR-372-3p (p=0.0028), miR-367-3p (p=0.0167) and miR-302d-3p (p=0.0061) distinguished between patients and controls. Abundant 2-ΔΔCt levels of each miRNA were found across all serum and CSF samples including biomarker-negative patients. Conclusion: With the largest data set so far, we underline the suitability of miR-371a, miR-372, miR-367 and miR-302d in serum and CSF for diagnosis of iGCT, particularly in biomarker-negative germinoma. Diagnosis of iGCT by miRNA analysis is a feasible and valid approach, particularly as serum can be readily obtained by a less invasive procedure. MiRNA analysis may discriminate iGCT from other tumors with similar radiological findings and may allow to monitor response to therapy as well as early relapse during follow-up.