Downregulation of microRNA-504 is associated with poor prognosis in high-grade glioma.

Several previous reports indicated that microRNA-504 (miR-504) has an oncogenic function through negatively regulating p53. On the other hand, a recent study revealed that miR-504 inhibits cancer cell proliferation through targeting CDK6 in hypopharyngeal squamous cell carcinoma (HSCC), suggesting the tumor suppressive role of this miRNA. However, the role of miR-504 in human malignant glioma remains unclear. Therefore, the aim of this study was to investigate the clinical significance of miR-504 expression in high pathological grade glioma. Quantitative real-time reverse transcriptive-PCR (qRT-PCR) was performed to examine miR-504 expression levels in 63 glioma tissues including 13 anaplastic astrocytomas (AA, WHO grade III) and 50 glioblastomas (GBM, WHO grade IV), as well as 10 non-neoplastic brain tissues. Associations between miR-504 expression and clinicopathological factors and prognosis of glioma patients were statistically analyzed. MiR-504 showed significant decreased expression levels both in AAs and GBMs relative to non-neoplastic brains (P ≤ 0.001, respectively). Additionally, low expression level of miR-504 was significantly associated with advanced WHO grade (P = 0.01). Moreover, Kaplan-Meier survival analysis showed that patients with low expression of miR-504 had significantly poor survival rate (P = 0.002). Cox regression analysis showed that miR-504 expression was independent prognosis-predicting factor for malignant glioma patients (P = 0.038; risk ration = 2.5). Our results suggest that miR-504 may be a prognostic predictor and be involved in tumorigencity as a tumor suppressor of malignant glioma.