MicroRNA in biofluids—Robust biomarkers for disease, toxicology, or injury studies: The case of minimally invasive colorectal cancer detection.
20 Background: MicroRNAs function as post-transcriptional regulators of gene expression. Their high relative stability in common clinical source materials (FFPE blocks, plasma, serum, urine, saliva, etc.) and the ability of microRNA expression profiles to accurately classify discrete tissue types and specific disease states have positioned microRNAs as promising new biomarkers for diagnostic application. Furthermore microRNAs have been shown to be rapidly released from tissues into the circulation with the development of pathology. Methods: Thousands of biofluid samples were profiled including blood derived plasma/serum and urine using a genome-wide LNA-based microRNA qPCR platform, which has unparalleled sensitivity and robustness even in biofluids with extremely low microRNA levels. Only a single RT reaction is required to conduct full miRNome profiling thereby facilitating high-throughput profiling without the need for pre-amplification. Results: Normal reference ranges for circulating microRNAs were determined in several biofluids, allowing development of qPCR arrays containing only relevant microRNA subsets present in various biofluids together with tissue specific microRNA markers. Procedures were developed to control pre-analytical variables, for quality checking and qualifying biofluid samples in particular serum and plasma but also urine and other biofluids. An extensive QC system was implemented in order to secure technical excellence and reveal any unwanted bias in the dataset. We currently screen and validate microRNAs biomarkers for cancer with the aim of developing minimal invasive tests to be applied in early detection population screens. Conclusions: The qPCR panels support development of robust biomarkers in disease, toxicology, and injury studies. We will demonstrate how panels may be quickly and robustly applied in biomarker discovery/validation projects using the specific case early detection of colorectal cancer in blood. Close attention is required on pre-analytical parameters. Hemolysis and cellular contamination affect miRNA profiles in biofluids and control is required.