[1015] micro-RNA Expression in Lethal and Non-Lethal Urothelial Cancers of the Bladder

Diana Rotzer, Aurel Perren, Achim Fleischmann. University of Bern, Bern, Switzerland

Background: MicroRNAs (miRNAs) are small non-coding RNA of 21–23 nucleotides which negatively regulate gene expression post-transcriptionally. miRNAs have been shown to play a role in tumorigenesis by regulating molecular pathways involved in e.g. epithelial–mesenchymal transition, metastasis and angiogenesis.
Design: We studied 20 muscle-invasive UCCs treated by radical cystectomy and standardized pelvic lymphadenectomy, 10 were lethal and 10 could be cured by surgery alone. Total RNA was extracted from formalin-fixed and paraffin-embedded (FFPE) tissue after testing different protocols in comparison to fresh frozen tissue. Reverse transcription was done with Megaplex RT Primers (Pool A and B) and the TaqMan miRNA reverse transcription kit (both Applied Biosystems) on a ABI GeneAmp 9700 Thermocycler. The subsequent profiling of 754 miRNAs was performed using TaqMan Array Human microRNA cards (A v2.0 and B v3.0). For normalization the median expression of all miRNAs was used and fold changes of individual miRNAs were calculated applying the DDCt method. All reactions were performed in triplicate and a negative control lacking cDNA was included.
Results: Mean expression level of 64 miRNAs were significantly different between lethal and non-lethal UCC (unadjusted p<0.05). However, the variance of the normalized CTs was large for all miRNAs in both groups and overlapped (roughly 50% of the top 20 miRNA). Therefore, expression signatures as classifier were tested and the scoring pair miRNA98 and miRNA204 performed rather well (p=0.089) given the small sample size. This miRNA pair allowed classifying 19 of the 20 patients correctly.
Conclusions: miRNA expression profiles in muscle invasive bladder cancer may help to identify patients at risk for lethal disease. Larger series are needed to further investigate the prognostic role of miRNA expression and profiles.
Category: Genitourinary (including renal tumors)

Wednesday, March 6, 2013 9:30 AM

Poster Session V # 144, Wednesday Morning

 

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