Detecting microRNA in human cancer tissues with fluorescence in situ hybridization

The technique of nucleic acid in situ hybridization is an effective method for identifying the existence and abundance of nucleic acids in tissue sections or cytological preparations. Such a method has the advantage of keeping morphological relationships intact while identifying changes at the molecular level. As a noncoding regulatory RNA, microRNA has been found to intricately control many physiological and pathological conditions. We provide here a representative fluorescence in situ hybridization protocol for microRNA detection, and note commonly used alternatives, and some troubleshooting points. The method described is based on formalin-fixed paraffin-embedded oral cancer tissues but should be broadly applicable to similarly processed tissues of other types of cancer.