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.