Altered microRNA (miRNA) expression may occur early in bladder cancer and may 
play a role in carcinogenesis and tumor behavior. We evaluated whether 
alterations in miRNA expression could improve disease stratification and outcome 
prognosis in bladder tumors and noninvasive diagnosis in urinary samples. 
miR-143, miR-222, and miR-452 expression levels were analyzed by quantitative 
RT-PCR (RT-qPCR) in paired urinary and matching tumors and in two independent 
prospective series of tumors and urinary specimens. Differential expression of 
miR-143, miR-222, and miR-452 in urine were verified by in situ hybridization in 
matching tumors. Tumor miRNA expression by RT-qPCR correlated with tumor grade, 
size, and presence of carcinoma in situ for miR-222, recurrence (miR-222 and 
miR-143), progression (miR-222 and miR-143), disease-specific survival 
(miR-222), and overall survival (miR-222). Protein expression patterns of 
potential miRNA targets, including vascular endothelial growth factor, BCL2, 
v-erb-b2 erythroblastic leukemia viral oncogene (ERBB) homolog 3, and ERBB4, 
were evaluated by IHC in tissue arrays containing tumors for which miRNAs were 
assessed by RT-qPCR. Target expression correlated with expression of their 
predicted regulatory miRNAs, recurrence (ERBB3), progression (ERBB4), 
disease-specific survival (ERBB3 and ERBB4), and overall survival (ERBB3 and 
ERBB4). Furthermore, RT-qPCR of miR-452 (area under the curve, 0.848) and 
miR-222 (area under the curve, 0.718) in urine provided high accuracies for 
bladder cancer diagnosis. Thus, bladder tumors were characterized by changes in 
miRNA expression that could aid in tumor stratification and clinical outcome 
prognosis, and miRNAs were detected in urinary specimens for noninvasive 
diagnosis.