Original ArticleBreast tissue-based microRNA panel highlights microRNA-23a and selected target genes as putative biomarkers for breast cancer

We explored the differential expression of breast tissue-based panel of microRNAs (miRNAs) and their potential application as prognostic markers of breast cancer (BC). This study was divided into the following phases: (1) A panel of 6 BC characteristic miRNAs, which were retrieved based on the microarray signature profiling (released by miRWalk), was explored using SYBR Green-based polymerase chain reaction (PCR) array in 16 cancerous and 16 noncancerous breast tissue; (2) pathway enrichment analysis of the key miRNA target genes; (3) marker choice and validation by real-time PCR in a larger set of 76 patients with BC, 36 benign breast conditions, and 36 healthy volunteers; (4) validation of miRNA (miR)-23a target genes (forkhead box m [FOXM1] and histidine-rich glycoprotein [HRG]) by conventional reverse transcriptase (RT)-PCR; and (5) the prognostic significance of the investigated parameters in the BC validation group was explored. In PCR array-based miRNA expression analysis, 4 miRNAs were found to be altered more than twice (miR-96, miR-29c, miR-221, and miR-23a). Bioinformatic analysis of the target genes revealed enrichment for special biological process categories, that is, cell cycle, angiogenesis, apoptosis, cell proliferation, and cell adhesion. miR-23a, HRG messenger RNA, and FOX messenger RNA were positive in BC by 82.9%, 72.4%, and 71.1%, respectively. The overall concordance rates between miR-23a with HRG and FOXM1 tissue RNAs were 91% and 79%, respectively. The median follow-up period was 49 months. mi-23a and HRG RNA were significant independent prognostic markers in relapse-free survival. miR-23a may have an oncogenic function and enhance BC progression by directly activating FOXM1 and HRG at RNA level.