Comparison of deep sequencing miRNA expression analysis in primary colorectal cancer and paired metastases.

e14682 Background: MicroRNAs (miRs) have been recognized as promising biomarkers because of their role in cancer biology while being protected from degradation in tissue and blood samples. It is unknown to what extent tumor derived miRs are differentially expressed between primary colorectal cancers (CRCs) and metastatic lesions and between tumor and the surrounding normal tissue. We analyzed and compared miR expression profiles of novel and known miRs in primary CRC tissue and metastases as well as their surrounding normal tissue. Methods: Total RNA was isolated from 125 snap-frozen resection specimens including 40 primary CRC, 45 metastases, 23 normal colorectal en 17 normal extracolonic tissues corresponding to paired primary tumor samples and metastases from 38 patients. MiR expression profiles were obtained by next generation sequencing (NGS) using the Illumina Highseq 2000 platform. Sequence data were aligned to miRBase(release 19). Prediction of novel candidate miRs was based on specific folding c...