Profile analysis of endogenous and exosomal microRNAs in human colon cancer cell lines-2

MicroRNAs (miRNAs) are intrinsic regulators in the various cellular processes, and their abnormalities are considered to be involved in the onset of human disorders, including cancer. Circulating miRNA is focused as new cancer biomarker however it is regarded that circulating RNA are released not only from tumor but also by various pathways. Recently, exosomes, small membrane vesicles, have been a major interest in cancer research field, because of their unique biological properties. Exosomes are secreted from various cells and the components (Lipids, mRNAs, miRNAs and proteins) reflect origin of the cells secreting them. Identification of exosomal miRNAs from cancer cells is expected to provide useful biomarkers of cancer. To identify specific exosomal miRNAs as candidate biomarkers for colorectal cancer, we compared exosomal miRNA profiles of 5 colon cancer cell lines with that of normal colon-derived epithelial cells, and isolated a subset of miRNAs as commonly-secreted miRNAs from colon cancer cells Endogenously expression of microRNAs were analyzed by Agilent Human miRNA V3 Microarray (G4470C) using total RNA of three human colon cancer cell lines (HT-29 cells, SW48 cells, and RKO cells) at two independent experiments. Exosomal microRNAs were analyzed by microRNA microarray using total RNA of exosomes from conditioned media of three human colon cancer cell lines, HT-29 cells, SW48 cells, and RKO cells at three independent experiments. Exosomes were prepared by step-wise ultra-centrifugation methods. RNA was prepared by Trizol or Trizol-LS reagent (Invitrogen) and RNeasy mini spin column (Qiagen).