The expression profiles of microRNAs in prostate epithelial cells

MicroRNAs (miRNAs) are non-protein-coding small RNAs in the size range 19–25 nucleotides (nt) that are cleaved from 70-100 nt hairpin pre-miRNA precursors.MiRNAs bind to complementary sequences in the 3′-untranslated regions of their target mRNAs and induce mRNA degradation or translational repression. Recent intensive studies have revealed that miRNAs play important roles in a large number of biological processes, including cellular differentiation, proliferation and death. These wide-ranging biological roles suggest that miRNAs may be involved in cancer development. MiRNAs regulate a variety of biological processes, including developmental timing, signal transduction, cell growth, and cell death. RNA labeling and hybridization were completed by KangChen Bio-tech Inc. (Shanghai, China) according to the manufacturer's instructions. Briefly,Total RNA was harvested using TRIzol (Invitrogen) and miRNeasy mini kit (QIAGEN) according to manufacturer’s instructions. After having passed RNA quantity measurement using the NanoDrop 1000, the samples were labeled using the miRCURY™ Hy3™/Hy5™ Power labeling kit and hybridized on the miRCURY™ LNA Array (v.18.0) which contains probes for 3100 mature miRNA.Following the washing steps the slides were scanned using the Axon GenePix 4000B microarray scanner.Scanned images were then imported into GenePix Pro 6.0 software (Axon) for grid alignment and data extraction. Replicated miRNAs were averaged and miRNAs that intensities>=30 in all samples were chosen for calculating normalization factor. Expressed data were normalized using the Median normalization. After normalization, significant differentially expressed miRNAs were identified through Volcano Plot filtering. Finally, hierarchical clustering was performed to show distinguishable miRNA expression profiling among samples.