Histopathological grading of papillary urothelial tumors (PUTs) of the urinary 
bladder is subjective and poorly reproducible. We investigated the relationship 
between the expression of frequently deregulated microRNAs (miRNAs) as well as 
their target genes (ZEB1/ZEB2) and bladder cancer histopathological grade in an 
attempt to find a miRNA that might allow more reliable grading of PUTs. We 
measured the expression levels of four miRNAs (miR-145, miR-205, miR-125b, and 
miR-200c) in 120 formalin-fixed, paraffin-embedded bladder tumor tissue samples 
using real-time PCR assays. ZEB1 and ZEB2 expression was assessed in the same 
bladder tissues by immunohistochemistry. MiR-205 distinguished low-grade 
papillary urothelial carcinoma (LG) from high-grade papillary urothelial 
carcinoma (HG), and miR-145 distinguished HG from infiltrating carcinoma (CA) 
with an area under the receiver operator characteristic curve (AUC) of 0.992 and 
0.997, respectively (sensitivity/specificity of 95.8/96.7 % and 100/91.7 %, 
respectively; p < 0.05). The expression level of miR-125b was significantly 
lower in LG than in PUNLMP, with an AUC value of 0.870 (93.3 % sensitivity and 
84.2 % specificity; p < 0.05). ZEB1 immunoreactivity was more frequently 
detected in HG than in LG (57 % vs 13 %, p < 0.01) and in HG than in CA (57 % vs 
17 %, p < 0.01). ZEB2 immunoreactivity was more frequent in CA than in HG (83 % 
vs 54 %, p < 0.05). ZEB1/ZEB2 and miRNAs expression seems to reliably 
distinguish between different grades of PUTs of the urinary bladder. They might 
well serve as useful complementary diagnostic biomarkers for grading of 
papillary urothelial tumors.