Urinary exosome miR-30c-5p as a biomarker of clear cell renal cell carcinoma that inhibits progression by targeting HSPA5

Exosome-derived miRNAs are regarded as biomarkers for the diagnosis and prognosis of many human cancers. However, its function in clear cell renal cell carcinoma (ccRCC) remains unclear. In this study, differentially expressed miRNAs from urinal exosomes were identified using next-generation sequencing (NGS) and verified using urine samples of ccRCC patients and healthy donors. Then the exosomes were analyzed in early-stage ccRCC patients, healthy individuals and patients suffering with other urinary system cancers. Afterwards, the target gene of the miRNA was detected. Its biological function was investigated in vitro and in vivo. The results showed that miR-30c-5p could be stably amplified. Its expression pattern was significantly different only between ccRCC patients and healthy control individuals, but not compared with that of other urinary system cancers, which indicated its ccRCC specificity. Additionally, the overexpression of miR-30c-5p inhibited ccRCC progression in vitro and in vivo. Heat shock Protein 5 (HSPA5) was found to be a direct target gene of miR-30c-5p. HSPA5 depletion caused by miR-30c-5p inhibition reversed the promoting effect of ccRCC growth. In conclusion, urinary exosomal miR-30c-5p acts as a potential diagnostic biomarker of early-stage ccRCC, and might modulate the expression of HSPA5, which is correlated with the progression of ccRCC. To study the expression pattern of exosomal miRNA in the samples from ccRCC patients and healthy control individuals, total RNA was first isolated from the urine exosomes. The contents of small RNAs in the exosomes of ccRCC patients and healthy control individuals were consistent. Afterwards, miRNAs were isolated from total RNA and next-generation sequencing (NGS) was performed to compare the urinary exosome miRNA expression pattern of ccRCC patients with that of healthy individuals. The samples were then analyzed using an ultra-sequencer Illumina HiSeq2500, a platform that can deliver high quality data. After quality controls and adapter elimination, only high quality reads were aligned using a mirDeep2 algorithm against the mirBase v21 database, for the identification and quantification of previously described miRNAs. In total, 126 miRNA species were identified.