Concentration of circulating miRNA-containing particles in serum enhances miRNA detection and reflects CRC tissue-related deregulations

// Abdou ElSharawy 1, 6 , Christian Roder 2 , Thomas Becker 3 , Jens K. Habermann 4 , Stefan Schreiber 1, 5 , Philip Rosenstiel 1 , Holger Kalthoff 2 1 Institute of Clinical Molecular Biology, Christian-Albrechts-University, Kiel, Germany 2 Institute for Experimental Cancer Research, Christian-Albrechts-University, Kiel, Germany 3 Department of General Surgery, Visceral, Thoracic, Transplantation and Pediatric Surgery, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany 4 Section for Translational Surgical Oncology and Biobanking, Department of Surgery, University of Lubeck and University Hospital Schleswig-Holstein, Campus Lubeck, Lubeck, Germany 5 Clinic for Internal Medicine I, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany 6 Faculty of Sciences, Division of Biochemistry, Department of Chemistry, Damietta University, New Damietta City, Egypt Correspondence to: Abdou Elsharawy, email: a.sharawy@mucosa.de Keywords: serum biomarker, extracellular microvesicles, miRNA-containing particles, colorectal neoplasms and inflammatory bowel disease, strand-specific miRNA deregulation Received: February 08, 2016     Accepted: September 12, 2016     Published: September 23, 2016 ABSTRACT The emerging potential of miRNAs as biomarkers for cancer detection demands parallel evaluation of strategies for reliable identification of disease-related signatures from easily accessible and pertinent body compartments. Here, we addressed whether efficient concentration of circulating miRNA-carrying particles is a rationale for miRNA biomarker discovery. We systematically compared miRNA signatures in 93 RNA preparations from three serum entities (whole serum, particle-concentrated, and particle-depleted fractions) and corresponding tissue samples from patients with colorectal cancer (CRC) as a model disease. Significant differences between whole sera and particle-concentrated serum fractions of CRC patients emerged for 45 of 742 tested miRNAs. Twenty-eight of these 45 miRNAs were differentially expressed between particle-concentrated serum fractions of metastatic CRC- and healthy individuals. Over half of these candidates (15 of 28) showed deregulations only in concentrated serum fractions, but not in whole sera, compared to the respective controls. Our results also provided evidence of a consistent downregulation of miR-486 and miR-92a, and further showed a possible “strand-specific” deregulation of extracellular miRNAs in CRC. More importantly, most of the identified miRNAs in the enriched sera reflected the patterns of the corresponding tumor tissues and showed links to cancer-related inflammation. Further investigation of seven serum pools revealed a subset of potential extracellular miRNA candidates to be implicated in both neoplastic and inflammatory bowel disease. Our findings demonstrate that enrichment and sensitive detection of miRNA carriers is a promising approach to detect CRC-related pathological changes in liquid biopsies, and has potential for clinical diagnostics.