miRNA profile of luminal breast cancer subtyptes in Slovak women

Objective: Aberrant expression of short, non-coding RNA molecules (miRNA) leads to breast cancer initiation, progression and metastasing. The miRNA expression level associates with imunohistochemical profile, histopathological parameters, clinical outcomes, prognoses and therapeutical response. The aim of this study was to analyse the whole spectrum of miRNA by microarray method and to define relevant miRNAs describing biological characteristics of luminal breast cancer subtypes. Design: Cross-sectional study, basic research. Setting: Biomedical center Martin, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Martin, Slovakia. Methods: We analysed 16 tissue samples of Luminal A/B breast cancer types and 16 breast tissue samples without pathological findings. The microarray technology by Agilent was used to analyse 2549 miRNAs by SurePrint G3 Human miRNA kit v.21. The results were assessed by AgiMicroRNA Bioconductor library within Limma pack. Results: The analyses of the lowest FDR p-value and the highest logFC value selected the oncomiR miR-182 as the most dominant with higher expression in cancer tissues than in normal tissues, followed by miR-21, miR342-3p/5p and miR-6826. The miR-4324 and cluster of miR-99a/let7c/miR-125b dominated in the group of miRNAs with lower expression in cancer tissues compared to normal tissues. Conclusion: The first results of this study complement biological characteristics of luminal breast cancer subptypes, represent basis for follow-up projects focused on the clarification of relevant signaling pathways and promise new and innovative breast cancer treatment based on the precise, tailored therapy by targeting specific miRNAs involved in the most important carcinogenesis mechanisms.