Abstract
Renal cell carcinoma (RCC) is the most commonly diagnosed renal tumor, consisting of ~3% of all malignancies worldwide. The prognosis of RCC can vary widely, and detecting patients at risk of recurrence at an early stage of disease may improve patient outcome. The factors presently used in a clinical setting cannot reliably predict the natural history of the disease. Therefore, there is a requirement to identify novel biomarkers that can aid in predicting patient outcome. Previous studies have indicated that microRNAs (miRNAs/miRs) are potential candidates as prognostic biomarkers for patients suffering from RCC. Consequently, the aims of the present study were to validate the potential of 3 of these miRNAs to predict the prognosis of patients with RCC, and to investigate the stability of endogenous control genes for miRNA studies in RCC tissues. The expression of 7 endogenous controls was measured using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) in formalin-fixed paraffin-embedded tumor and benign tissues from patients suffering from clear cell RCC (ccRCC). The analyses identified RNU48 and U47 as the most stable endogenous controls. The expression of miR-126, miR-21 and miR-10b was analyzed using RT-qPCR in renal tissues from 116 patients diagnosed with ccRCC. All three investigated miRNAs were differentially expressed between malignant and benign tissues. miR-126 and miR-10b were also differentially expressed between grades and stages of ccRCC. In a univariate, but not in a multivariate model, low expression of miR-126 was associated with shorter time to recurrence of the disease. The results of the present study indicate that of the 3 miRNAs investigated, the expression of miR-126 has the strongest potential as a prognostic biomarker for patients suffering from ccRCC.