MicroRNAs in tumor samples and urinary extracellular vesicles as a putative diagnostic tool for muscle-invasive bladder cancer.

PURPOSE: The identification of biomarkers characterizing the invasive potential of bladder cancer could enhance the clinical management of individual patients and therefore improve prognosis. The aim of this study was to define a miRNA panel in tumor tissues as well as in urinary extracellular vesicles (EVs) for discriminating muscle-invasive bladder cancer (MIBC) from non-muscle-invasive bladder cancer (NMIBC). METHODS: miRNA expression was analyzed in 24 formalin-fixed, paraffin-embedded (FFPE) tumor samples by microarray analysis and was further validated by qRT-PCR in 56 FFPE tumor samples as well as in 37 urinary EV samples. RESULTS: Microarray analysis revealed 63 miRNAs that were significantly differentially expressed (P < 0.05) between tissues from MIBC and NMIBC tumors. Five selected miRNAs (miR-146b-5p, miR-155-5p, miR-138-5p, miR-144-5p, and miR-200a-3p) were validated by qRT-PCR. The expression of all except miR-144-5p was significantly associated with high tumor grade. In urinary EVs, a different expression was verified for miR-146b-5p (P = 0.004) and miR-155-5p (P = 0.036), which exhibited significantly higher expression in urinary EVs from patients with MIBC. CONCLUSIONS: miRNAs are promising biomarkers for the identification of invasive bladder carcinomas. Tissue samples as well as urinary EVs may serve as sources for miRNA analysis. This method, in addition to histopathology, could provide a new diagnostic tool and facilitate individual therapeutic decisions to select patients for early cystectomy.

Exosomes of invasive urothelial carcinoma cells are characterized by a specific miRNA expression signature.

Muscle-invasive bladder cancer (MIBC) represents a highly aggressive tumor type compared to non-muscle-invasive tumors. MIBC is characterized by specific molecular alterations, which may also modulate extracellular tumorigenic effects. Tumor-associated exosomes, especially exosomal miRNAs, are important regulators in the interaction between tumor cells and tumor microenvironment by affecting tumor-promoting processes in target cells. It is important to analyze whether their exosomal patterns also reflect the specific molecular characteristics of MIBC. The aim of this study was to compare the miRNA expression in secreted exosomes from urinary bladder cancer cells (UBC) with different degrees of invasiveness. By electron microscopy, nanotracking analysis and western blot we proofed a high quality of isolated exosomes. Microarray analysis identified an invasion-associated signature of 15 miRNAs, which is significantly altered in exosomes of invasive UBC compared to non-invasive counterparts. Therefrom, 9 miRNAs are consistent differently expressed in both, invasive cells and their secreted exosomes. The remaining 6 exosome-specific miRNAs are only deregulated in exosomes but not in their parental cells. MiRNA alterations were verified by qPCR in cell culture and urinary exosomes. In conclusion, we showed that exosomes from invasive UBC cells are characterized by a specific miRNA signature. Further analyses have to clarify the functional relevance of exosomal miRNAs secreted by invasive bladder cancer cells for modification of the tumor microenvironment and their putative role as molecular markers in liquid biopsies.

MicroRNAs with prognostic potential for metastasis in clear cell renal cell carcinoma: a comparison of primary tumors and distant metastases.

BACKGROUND: MicroRNAs (miRNAs) are regulators of gene expression in tumor development and progression. However, their influence on metastasis of clear cell renal cell carcinoma (ccRCC) is less understood. To determine the role of miRNAs in metastatic progression, miRNA expression in primary ccRCC was compared to distant metastases. METHODS: Total RNA of 53 primary ccRCCs, 35 distant metastases from lung, bone, brain, and abdomen, as well as 17 normal kidney tissues was isolated from fresh frozen tissue and formalin-fixed paraffin-embedded (FFPE) samples. The miRNA microarrays were performed based on fresh frozen tissue. Results were validated by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) on fresh frozen tissue and FFPE samples. Real-time cell analyses and transwell invasion assays were carried out after transient transfection of microRNA-30c (miR-30c) in cell line 786-O. RESULTS: There were 14 miRNAs differently expressed in metastatic primary ccRCC and distant metastases compared to non-metastatic primary tumors. A strong correlation of miRNAs to progression-free- and cancer-specific 5-year-survival was determined. Specific miRNAs were differently expressed in distant metastases compared to primary ccRCC. A miRNA signature distinguished lung metastases from other metastatic sites. Overexpression of miR-30c increased adherence and decreased migration and invasion in the ccRCC cell line. CONCLUSIONS: MiRNAs are deregulated in metastatic primary ccRCC and could be promising prognostic markers for an early prediction of metastasis. Alterations in miRNA expression characterize distant metastases of different metastatic sites. Furthermore, our study suggests a functional role of miR-30c in metastasis. The miRNAs could be a helpful tool for individual follow-up prediction and personalized therapy selection.