Background Piwi-interacting RNAs (piRNAs) are small RNAs of 27–30 nucleotides
mapping to transposons or clustering in repeat genomic regions. Preliminary
studies suggest an important role in cancerogenesis. This study is the first
one investigating their prognostic impact in clear cell renal cell cancer
(ccRCC) patients. Methods Three piRNAs (piR-30924, piR-57125, and piR-38756)
selected on the basis of initial piRNA microarray analyses were determined
using RT-qPCR in non-metastatic (n = 76) and metastatic (n = 30) ccRCC tissue
at the time of nephrectomy in comparison to normal renal tissue (n = 77) and
tissue from distant ccRCC metastases (n = 13). Primary clinical end points
were recurrence-free and overall survival. Results piR-57125 showed lower
expression in metastatic than in non-metastatic tumors, whereas the expression
of piR-30924 and piR-38756 increased in metastatic tumors. The higher
expression of piR-30924 and piR-38756 as well as the lower expression of
piR-57125 in metastatic primary tumors were significantly associated with
tumor recurrence and overall survival. Multivariate Cox regression analyses
revealed both piR-30924 and piR-57125 as independent prognostic predictors.
This impact was even more pronounced in non-metastatic patients. Conclusions
This study demonstrates that the expression levels of these piRNAs in primary
non-metastatic and metastatic ccRCC tissue can serve as potential prognostic
biomarkers in combination with clinicopathological factors
