Overexpression of circulating miRNA-21 and miRNA-146a in plasma samples of breast cancer patients.

Breast cancer is the second most common malignant disease affecting Indian women and is the leading cause of cancer-related mortality. MicroRNAs (miRNAs) are remarkably stable in blood, which makes them novel and promising biomarkers for cancer detection and diagnosis. In this study, we investigated whether expression levels of circulating specific miRNAs, such as microRNA-21 (miR-21) and microRNA-146a (miR-146a) could be used as potential biomarkers in plasma of breast cancer patients and healthy individuals. We compared the expression levels of breast cancer associated specific miRNA--miR-21 and miR-146a in plasma samples of histopathologically reported 14 patients (aged 35-61 yrs) with breast cancer and an additional 8 healthy volunteers (aged 35-54 yrs). The miRNA expression level was determined by TaqMan quantitative PCR (qPCR) assay. The miRNA expression level of each sample was normalized to that of miR-16 as reference and expressed as relative expression (2(deltaCt)). Our results showed that the circulating level of miR-21 and miR-146a were significantly higher in plasma samples of breast cancer patients, when compared to those of healthy controls (p < 0.0004 and p < 0.005, respectively). Thus, analyzing expression of miR-21 and miR-146a from plasma samples of breast cancer patients might be useful in the diagnosis of breast cancer. However, further studies with larger number of patients and control individuals are needed to confirm the results.