Low serum level of miR-485-3p predicts poor survival in patients with glioblastoma

Abstract

MicroRNAs (miRNAs) are short noncoding RNAs that play critical roles in human malignancies and can be used as biomarkers for cancer. Until now, a number of biomarkers for prognosis of glioblastoma (GBM) have been reported in tumor tissues but only a few biomarkers in circulating fluid. Using a custom microarray, we previously identified 19 differentially expressed miRNAs in serum of patients with GBM. In this study, we investigated whether 3 of the 19 miRNAs in serum could be used as prognostic biomarkers for patients with GBM. We first validated the serum levels of 3 candidate miRNAs in an independent cohort of 24 GBM patients and 12 healthy volunteers by real-time quantitative reverse transcription PCR (qRT-PCR), and then evaluated the prognostic value of these miRNAs in a total of 36 GBM patients. The results show that the serum levels of the 3 miRNAs (miR-451a, miR-485-3p and miR-4298) determined by qRT-PCR are significantly different between 24 GBM patients and 12 healthy volunteers (all P <0.05) and are in concordance with the results of microarray analysis. High serum level of miR-451a is correlated with positive tumor O(6)-methylguanine-DNA methyltransferase (MGMT) expression (P = 0.040). Survival analysis showed that low serum miR-485-3p level is associated with poor progression-free survival (PFS) (P < 0.004) and overall survival (OS) (P < 0.023). Furthermore, univariate and multivariate Cox analyses demonstrated that that serum miR-485-3p expression is a significant independent prognostic factor for PFS and OS in GBM patients. In conclusion, serum miR-485-3p level is reduced and might be a potential prognostic biomarker in GBM patients.

Fig 1. Validation of serum levels of miR-451a, miR-485-3p and miR-4298 by qRT-PCR in GBM patients.

The average serum levels of the 3 miRNAs in GBM patients (n = 24) were compared with those in healthy volunteer controls (n = 12). (A) serum level of miR-451a in GBM patients is significantly higher than that in healthy controls. (B) serum level of miR-485-3p in GBM patients is significantly lower than that in healthy controls. (C) serum level of miR-4298 in GBM patients is significantly lower than that in healthy controls. The serum levels of the 3 miRNAs in GBM patients are in concordance with the results of microarray analysis. miRNA levels in each sample were normalized to miR-16. ΔCt = mean value of Ct (reference miRNA16)–mean value of Ct (target miRNA).

Fig 2. Comparison of overall survival (OS) and progression-free survival (PFS) of the GBM patients with lowand high levels of serum miR-451a, miR-485-3p and miR-4298.

(A) There is no difference of survivals (OS and PFS) between patients with a low and high level of serum miR-451a (B) Patients with a low level of serum miR-485-3p had significantly shorter OS (P = 0.023) and PFS (P = 0.004) than those with a high level. (C) There is no difference of survivals (OS and PFS) between patients with a low and high level of serum miR-4298.