Do microRNA 96, 145 and 221 expressions really aid in the prognosis of prostate carcinoma?

MicroRNAs (miRs) are small noncoding RNAs that have been reported to be promising diagnostic tools. We used quantitative real-time reverse transcription PCR (RT-qPCR) to analyze differentially expressed miRNAs in prostate tumor samples to determine its prognostic value. From 2007 to 2009, tumor tissues were obtained from 73 radical prostatectomy specimens. Differentially expressed miR-96, -145 and -221 were validated by TaqMan RT-qPCR using all 73 tissues. The prognostic value was assessed in terms of biochemical recurrence using Kaplan-Meier and Cox regression analyses. For our patient cohort, the mean age was 64.7 years (50-76 years) and the mean prostate-specific antigen (PSA) was 7.5 ng ml(-1). During the follow-up period (mean, 19.4 months), 14 of 73 (19.2%) patients developed biochemical recurrence. Expression of miR-96, -145 and -221 correlated strongly with each other, but there were no correlations between miRNA expression and clinicopathologic parameters. Kaplan-Meier survival curves using the log-rank test showed a decreased biochemical recurrence-free interval with pathologic stage (P<0.001). In addition, patients with Gleason scores over 8, compared with those with a Gleason score of 6, showed a decreased biochemical recurrence-free interval in Kaplan-Meier analysis (P=0.001). However, expression of miR-96, -145 and -221 did not correlate with the biochemical recurrence interval in Kaplan-Meier survival curves or by multivariate analysis using the Cox proportional hazard regression model, either. In conclusion, we did not observe a significant correlation between the expression of miR-96, -145 and -221 and clinicopathologic parameters. To utilize miRNA as a diagnostic tool in clinical practice, more research is needed to understand miRNA mechanisms, identify miRNA targets, and further characterize miRNA function.