Differential expression of miR-21, miR-125b and miR-191 in breast cancer tissue

Aims: To develop new biomarkers for early detection and to inform effective clinical management of breast cancer. Methods: Real-time polymerase chain reaction was used to profile microRNA (miRNA) in tumor tissue from 50 breast cancer patients using non-tumor breast tissue from each patient as a control. We have focussed on three miRNA; miR-21, miR-125b and miR-191, all of which have been implicated in breast cancer with either proven or predicted target genes involved in critical cancer-associated cellular pathways. Results: Upregulation of miR-21 and miR-191 and downregulation of miR-125b, was found in breast cancer tissue. Combined expression analysis of miR-125b/miR-191 increased sensitivity to 100% and specificity to 94% while miR-21/miR-191 increased to 92% and 100%, respectively. Therefore, combination of two miRNA gives a better prediction than individual miRNA. Conclusions: We could differentiate between breast cancer and adjacent non-tumor breast tissue as a control with a high degree of sensitivity and specificity in the Mexican population using a combined expression analysis of only two miRNA. These observations, although a proof of principle finding at this time, show that a combined expression profile of two miRNA (miR-125b/miR-191 and miR-21/miR-191) can discriminate between breast cancer and non-tumor tissue with high specificity and sensitivity.