New mechanistic insights of clear cell renal cell carcinoma from integrated miRNA and mRNA expression profiling studies.

Differentially expressed (DE) microRNAs (miRNAs) in clear cell renal cell carcinoma (ccRCC) tissues from pooled samples were reported to affect the tumorigenesis and progression of ccRCC. However, systematic studies on the miRNA-mRNA regulatory networks involved in various pathways in all four stages of the disease are lacking. In this study, we applied microarray technology to perform an integrated analysis of the miRNome and transcriptome in ccRCC tissues from patients at different stages of ccRCC. A total of 604 DEmiRNAs and 6892 DEgenes (DEGs) were identified by comparison with corresponding adjacent normal tissues. The pairing of miRNAs with DEGs were searched using validated miRWalk module, and the pairs were confirmed by comparing with DEmiRNAs in our study. Our results demonstrated that different stages of ccRCC had distinct miRNA/mRNA profiles. However, four common pathways (the complement and coagulation cascades, the pathway for the metabolism of xenobiotics by cytochrome P450, the PPAR signaling pathway, and the pathway for aldosterone-regulated sodium reabsorption) were enriched by targets of DEmiRNAs at all stages of ccRCC. We carried out an extensive analysis of data on miR-16, which had the most target genes, and found that its differential expression was validated in The Cancer Genome Atlas dataset. We also verified the correlation between miR-16 expression and target pathways by gene set enrichment analysis and in vitro experiments. High miR-16 level was also associated with shorter survival time in ccRCC. Our work presents a systematic profiling of miRNA, mRNA and pathways regulated by miRNAs in different stages of ccRCC. Our cross-omics results also identify four common pathways that function aberrantly in all stages of the disease. These pathways are likely to be critical in occurrence and progression of ccRCC. These common dysfunctional pathways have the potential to serve as therapeutic targets and diagnostic biomarkers, whereas miRNAs (miR-20, 484, 497) differentially expressed in only stage I tissues and in blood could be used to diagnose early-stage ccRCC patients.