RNA sequencing quantitative analysis of exosome miRNAs in plasma in Metastatic renal cell carcinoma (mRCC)

Purpose: Since clinical characteristics are often inaccurate and subjective, we evaluated the prognostic value of plasma exosomal miRNAs to predict survival in metastatic renal cell cancer (mRCC). Methods: RNA sequencing was performed to identify candidate exosomal miRNAs associated with overall survival in a screening cohort of 41 mRCC patients.Candidate miRNAs were further evaluated for prognosis by TaqMan quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) in a follow-up cohort of 65 mRCC patients. Results: RNA sequencing in screening cohort generated 3.75 million mappable reads per patient, of those with normalized read counts>8 RPM (reads per million), 93.8% were mapped to miRNAs for a total of 322 unique miRNAs. Cox regression analysis identified 20 miRNAs that were associated with overall survival (OS, FDR< 0.05). Among these 20 significant miRNAs, three were validated in a separate independent cohort of 65 patients with mRCC.Patients with lower expression of miR-26a1-3p, miR-let-7i-5p and miR-615-3p had a significantly poorer OS than those with higher expression. Multivariate model by combining miR-let-7i-5p and the Memorial Sloan-Kettering Cancer Center (MSKCC) score significantly improved survival prediction. Conclusions: Our study identifies multiple plasma exosomal miRNAs showing association with survival in mRCC stage patients. Multivariate model by combining miR-let-7i-5p and the Memorial Sloan-Kettering Cancer Center (MSKCC) score significantly improved survival prediction. exosomal miRNAs profiles of 41 mRCC patients were generated by 50 bp single read sequencing using Illumina HiSeq2000 DNA sequence analyzer.