Urine is emerging as a biological fluid suitable to perform liquid biopsy in a minimally invasive manner, a fundamental attribute for prevention and early detection of cancer. Urine biomarkers can be analyzed in voided urine, in urine sediment, and urine supernatant. In the case of urothelial carcinoma, in which tumor cells are in direct contact with urine, the assessment of the levels of biomarkers in the urinary cell fraction appears to be the most promising approach to identify diagnostic and prognostic biomarkers in a noninvasive way. Here, we describe a protocol to collect and process urine samples to obtain urinary exfoliated cells. Furthermore, we describe the methodology to isolate RNA from urinary cells and to quantify gene expression levels from these urinary cells.
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