Correlation of MicroRNA 132 Up-regulation with an Unfavorable Clinical Outcome in Patients with Primary Glioblastoma Multiforme Treated with Radiotherapy Plus Concomitant and Adjuvant Temozolomide Chemotherapy

BACKGROUND: MicroRNA 132 (miR-132) is dysregulated in a range of human malignancies; however, its role in glioma has not been reported. The aim of this study was to profile miR-132 expression in a cohort of patients with primary glioblastoma multiforme (GBM) treated with the Stupp regimen and to correlate microRNA levels with patient outcome. METHODS: miR-132 levels relative to RNU44 were assessed by quantitative reverse transcription-polymerase chain reaction in 43 GBMs and normal brain tissue. The cohort comprised patients less than 72 years of age with Eastern Cooperative Oncology Group (ECOG) scores between 0 and 2 who had undergone 6-week concomitant radiation and temozolomide followed by adjuvant temozolomide. Survival data were available for all cases. Tumors were characterized for O6-methylguanine-DNA methyltransferase (MGMT) methylation and isocitrate dehydrogenase (IDH) 1/2 mutation status. Associations between miR-132 expression and clinical indicators were analyzed. RESULTS: Tumor miR-132 levels ranged from 0.07-to 40.4-fold increase (mean = 5.5-fold increase) relative to normal brain. High-level miR-132 (above the mean) independently predicted for a significantly shorter overall survival (P =.008). miR-132 was a stronger prognostic indicator than ECOG score (P =.012) and age at diagnosis (P =.026) but did not correlate with MGMT methylation status or extent of tumor resection. Cox regression analysis confirmed high miR-132 as the strongest predictor of outcome (P =.010) with a hazard ratio of 2.8. CONCLUSIONS: This study identified high miR-132 expression as a biomarker of poor prognosis in patients with primary GBM treated with the Stupp regimen.