In situ hybridization detection of miRNA using LNA™ oligonucleotides

MicroRNAs are a family of small noncoding ribonucleic acids involved in regulation of gene activity. They have been implicated in both normal cellular pathways related to proliferation, differentiation, and apoptosis and pathological processes leading to disease. It is believed that better understanding of their structure and function will shed more light on a number of cellular functions while at the same time providing the basis for development of novel therapeutic applications. That is why identification and quantification of miRNAs are of great scientific interest. Several techniques have been developed which allow accurate, fast, and easy detection of these RNA species. This chapter focuses on in situ hybridization (ISH), a method which combines identification of miRNAs with histochemistry (ICH). We describe in detail a protocol for ISH in formalin-fixed paraffin-embedded tissue with the help of synthetic nonradioactive LNA oligonucleotide probes.