Molecular Characterization of Breast Cancer Subtypes from Joint Analysis of High Throughput miRNA and mRNA Data (II)

MicroRNAs (miRNAs) are a class of short, single-stranded widely expressed noncoding RNAs that regulate the stability or translational efficiency of target messenger RNAs. Date derived from expression profiling of 489 miRNAs in 101 human primary breast tumor samples, along with genome-wide matched mRNA profiling and extensive clinical information were investigated in this study. miRNA and mRNA expression were analyzed using correlations and enrichments analyses. The results show that particular cellular processes such as proliferation, cell adhesion, and immune response are significantly enriched among genes with strong positive or negative correlation to individual or groups of miRNAs. Functional analyses were performed to validate the influence of miRNAs on proliferation. A group of miRNAs was identified that is associated to breast cancer disease free survival. This study provides a comprehensive dataset that can be used as groundwork for further studies of the involvement of miRNA in breast cancer. miRNA profiling from 101 breast cancer samples was performed. Experiments were mostly performed using duplicate hybridizations (99 samples) on different arrays and time points. Two samples were profiled only once. miRNA signal intensities for replicate probes were averaged across the platform, log2 transformed and normalized to the 75 percentile. miRNA expression status was scored as present or absent for each gene in each sample by default settings in FE v9.5. miRNAs in samples that were run in replicates were considered present if scored in one of the two arrays. mRNA profiling from 115 breast cancer samples was performed. Replicates not included. Four new arrays were added in this version with 115 samples versus the one with 114 samples (GSE19536). For samples 34, 107 and 185, a new array replaces the old one, generally with only small differences in values. Sample 391 is added to the 115 sample dataset. Replicates not included.