Comparison of miRNA expression profiles in normal and malignant prostate tissues. Keywords: microarray analysis of microRNA expression profiles MicroRNA expression was compared between normal prostate tissue from either young subjects that died of trauma, or normal adjacent to tumor, and prostatic tumors in older prostate cancer patients. RNA was isolated from frozen tissue sections, enriched for the miRNA fraction, which was subsequently labeled and hybridized to miRNA microarrays for expression profiling analysis.