MicroRNA is known to be an important regulator of gene expression. Researchers from Chonnam National University Medical School, Korea selected microRNAs that were found to be differentially expressed in normal urothelium and urothelial carcinomas in the literature. microRNAs identified ny microarray in two expression profiling studies conducted by LC Science customers’ Friedman et al. 2009 and Song et al. 2010 were selected. Meaningful microRNAs were validated using urothelial tumor cells lines; formalin-fixed and paraffin-embedded (FFPE) tissues; and urine samples for both the definitely benign and malignant categories. Diagnostic utility was also assessed  by  applying  validated  microRNAs  to  urine  specimens in  the  “atypical  urothelial  cells”  category  of  the  Paris System for Reporting Urine Cytology. Among the 25 consistently directed microRNAs in 2 or more studies, 14 microRNAs were upregulated and 11 downregulated. In urothelial tumor cell lines, 3 microRNAs were upregulated and 8 microRNAs were downregulated. In the step using FFPE tissues, four microRNAs (miR-145, miR-133a, miR-125b, and miR-99a) levels were downregulated and four microRNAs (miR-96, miR-141, miR-200c, and miR-205) were upregulated in the entire spectrum of urothelial neoplasms. Similar expression profiles were observed in urine specimens of “negative for high-grade urothelial carcinoma” and “urothelial carcinoma”. The expression of miR-99a revealed different trends among the atypical urothelial categories. The findings from this study show that consistently  upregulated  or  downregulated  microRNAs  might  be  involved  in  tumorigenesis  or  progression  of  urothelial  carcinoma and that they could be used as potential diagnostic or prognostic markers.

MicroRNA expression in the “atypical urothelial cells” category of the Paris System for Reporting Urine Cytology

LC Sciences
When “atypical urothelial cells” was proven to be benign when followed up (abbreviated as AN), the expression of miR-99a increased as in the “negative” category urine (abbreviated N). When “atypical urothelial cells” was proven malignant when followed up (abbreviated as AU), the expression of miR-99a decreased as in the “malignant” category urine (abbreviated as UC).
 
Reference
Kim SS, Choi C, Kwon DD. (2017) Urinary microRNAs as potential biomarkers for differentiating the “atypical urothelial cells” category of the Paris system for reporting urine cytology. Int J Clin Exp Pathol 10(8):8303-8313. [article]

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