Abstract 3987: Exosomal microRNA in cell-free urine samples as a source for liquid prostate cancer biopsy

MicroRNAs constitute a class of small cellular RNAs (typically 19-23 nt) that function as post-transcriptional regulators of gene expression. Current estimates indicate that more than one third of the human cellular transcriptome is regulated by this small class of RNA (∼2000 miRNA). MicroRNAs have been shown to be actively exported from tissues into the circulation through a variety of mechanisms including complexing with RNA binding proteins or HDL and through active exosome transport. Exosomes are nanovesicles secreted into the extracellular environment by a wide range of cell types under normal and pathological conditions. As the profile of exosomal microRNAs may be a fingerprint of the releasing cell type and because they are released in easily accessible body fluids such as blood and urine, their microRNA content holds potential as biomarkers for early detection of malignancy. Cell free urine samples are an obvious liquid biopsy source for microRNA markers in prostate cancer and could serve as diagnostic tools as well as treatment response markers. Yet microRNA levels in urine samples are extremely sparse and cannot be detected reliable by conventional sample preparation methods. It has been reported that tumour derived exosomes carrying genetic information specific for prostate cancer can be measured in urine samples following prostate massage. However, a methodology eliminating the need for prostate massage of every patient to be tested in a clinical setting is highly desirable. The purpose of this study was to combine a simple exosomal enrichment method with our highly sensitive LNA™-based qPCR platform for detection of microRNAs and apply this to a cohort consisting of more than 300 cell free urine samples from prostate cancer cases and controls. In conclusion, cell free urine samples holds potential as a liquid biopsy source for exosomal microRNA markers in prostate cancer, showing miRNA signatures of strong diagnostic potential. Analysis is pending and data will be presented. Citation Format: Thorarinn Blondal, Anni R. Thomsen, Jorg Krummheuer, Michael Borre, Jacob Fredsoe, Christa Haldrup, Ditte Andreasen, Maria W. Teilum, Niels Tolstrup, Karina D. Sorensen, Torben F. Orntoft, Peter Mouritzen. Exosomal microRNA in cell-free urine samples as a source for liquid prostate cancer biopsy. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3987. doi:10.1158/1538-7445.AM2015-3987