MiR-30a-5p Inhibits Epithelial-to-Mesenchymal Transition and Upregulates Expression of Tight Junction Protein Claudin-5 in Human Upper Tract Urothelial Carcinoma Cells

The involvement of microRNAs (miRNAs) in cancer development and their potential as prognostic biomarkers are becoming increasingly known. However, the signature of miRNAs and their regulatory roles in tumorigenesis of upper tract urothelial carcinoma (UTUC) remain to be elucidated. This study aimed to profile the miRNA expression pattern in UTUC tumor tissues and identify candidate miRNAs with prognostic and/or therapeutic functions. METHODS AND RESULTS We collected 22 UTUC tissue and adjacent normal tissues samples from patients who underwent nephroureterectomy. The miRNAs signatures of three selected UTUC samples using next-generation sequencing showed that miR-30a-5p was significantly downregulated in UTUC tumors compared to adjacent normal tissues. The differentially-expressed miRNAs were specifically validated by quantitative real-time polymerase chain reaction. In addition, the miRNA expression signatures were analyzed with the transcriptome profile characterized by microarray. Further in vitro studies indicated that overexpression of miR-30a-5p significantly suppressed proliferation, migration, and epithelial-to-mesenchymal transition (EMT) in cultured BFTC-909 UTUC cells. As a potential target gene of miR-30a-5p in the tight junction pathway suggested by the pathway enrichment analysis, the reduced expression of tight junction protein claudin-5 in UTUC cells was demonstrated to be upregulated by miR-30a-5p genetic delivery. CONCLUSIONS Taken together, our findings demonstrated that miR-30a-5p inhibits proliferation, metastasis, and EMT, and upregulates the expression of tight junction claudin-5 in UTUC cells. Thus, miR-30a-5p may provide a promising therapeutic strategy for UTUC treatment.