Expression Levels of PIWI-interacting RNA, piR-823, Are Deregulated in Tumor Tissue, Blood Serum and Urine of Patients with Renal Cell Carcinoma

Background: Renal cell carcinoma (RCC) is the most common neoplasm of adult kidney accounting for about 3% of adult malignancies. P-Element induced wimpy testis (PIWI)-interacting RNAs (piRNAs) are a new class of naturally occurring, short non-coding RNAs involved in silencing of transposable elements and in sequence-specific chromatin modifications. There were preliminary data published indicating that piR-823 expression is deregulated in circulating tumor cells and tumor tissue in gastric and kidney cancer, respectively. Patients and Methods: In our study, we analyzed piR-823 levels in 588 biological specimens: tumor tissue (N=153), adjacent renal parenchyma (N=121), blood serum (N=178) and urine (N=20) of patients undergoing nephrectomy for RCC; and in blood serum (N=101) and urine (N=15) of matched healthy controls. Expression levels of piR-823 were determined in all biological specimens by quantitative real-time polymerase chain reaction, compared in patients and controls, and correlated with clinicopathological features of RCC. Results: We identified a significant downregulation of piR-823 in tumor tissue [p