PIWI-Interacting RNA Pathway Genes: Potential Biomarkers for Clear Cell Renal Cell Carcinoma.

5 piRNA pathway genes (TDRD7, GPAT2, PLD6, SUV39H1, and DOM3Z) were picked out and used to construct the piRNA pathway gene risk model. Kaplan-Meier survival curve analysis showed that compared with that of the low-risk group of ccRCC patients, the OS of the high-risk group of ccRCC patients was significantly reduced. The predictive performance of the prognostic risk model was measured using a ROC curve, which individually showed AUC values for 1 year of 0.707, for 3 years of 0.713, and for 5 years of 0.701. Moreover, the mRNA and protein expression levels of TDRD7 were overexpressed in the ccRCC datasets (data from our cohort, TCGA, GEO, and CPTAC) and ccRCC cell lines, and the expression levels correlated with the clinicopathological characteristics in ccRCC. The Tumor Immune Estimation Resource (TIMER) showed that the mRNA expression level of TDRD7 was positively related to tumor immune infiltrating cells (TICs) in ccRCC. Mechanistically, gene set enrichment analysis (GSEA) was performed to uncover the mechanism of TDRD7 in ccRCC. In summary, the piRNA pathway genes,especially TDRD7, may be potential cancer diagnostic and prognostic biomarkers of ccRCC.