Electrochemical miRNAs Determination in Formalin-Fixed, Paraffin-Embedded Breast Tumor Tissues Association with HER2 Expression

Whilst breast cancer (BC) management continues to improve, the requirement of novel assays to support the accuracy of HER2 clinical diagnosis remains. Investigation of the potential for miRNAs, recently identified biomarkers of both predictive and prognostic value in BC, to fulfill this role, holds much promise. In this communication we report a new electrochemical strategy, to determine miRNA in formalin-fixed, paraffin-embedded (FFPE) tissue sections from different breast cancer profiles of human patients. We have recently developed a rapid and accurate method to analyze two different target miRNAs in tissue samples. This strategy involves the selective and efficient capture of the DNA/miRNA heteroduplexes, formed by hybridization between the target miRNA and a specific biotinylated DNA probe. This method also includes antibody-conjugated magnetic beads, their labeling with an enzymatic polymer and amperometric transduction using the H2O2/hydroquinone (HQ) system at disposable screen-printed carbon electrodes (SPCEs). Quantitative results achieved with the electrochemical bioplatform in the analyzed FFPE tissue samples demonstrated an association of both miRNAs expression with the clinico-pathological features of the specimens. Moreover, the feasibility to identify HER2 tumor subtype proved a similar sensitivity and accuracy as that obtained with fresh-frozen samples.