Circulating exosomal microRNAs as biomarkers of colon cancer.
OBJECTIVE
Exosomal microRNAs (miRNAs) have been attracting major interest as potential diagnostic biomarkers of cancer. The aim of this study was to characterize the miRNA profiles of serum exosomes and to identify those that are altered in colorectal cancer (CRC). To evaluate their use as diagnostic biomarkers, the relationship between specific exosomal miRNA levels and pathological changes of patients, including disease stage and tumor resection, was examined.


METHODS
Microarray analyses of miRNAs in exosome-enriched fractions of serum samples from 88 primary CRC patients and 11 healthy controls were performed. The expression levels of miRNAs in the culture medium of five colon cancer cell lines were also compared with those in the culture medium of a normal colon-derived cell line. The expression profiles of miRNAs that were differentially expressed between CRC and control sample sets were verified using 29 paired samples from post-tumor resection patients. The sensitivities of selected miRNAs as biomarkers of CRC were evaluated and compared with those of known tumor markers (CA19-9 and CEA) using a receiver operating characteristic analysis. The expression levels of selected miRNAs were also validated by quantitative real-time RT-PCR analyses of an independent set of 13 CRC patients.


RESULTS
The serum exosomal levels of seven miRNAs (let-7a, miR-1229, miR-1246, miR-150, miR-21, miR-223, and miR-23a) were significantly higher in primary CRC patients, even those with early stage disease, than in healthy controls, and were significantly down-regulated after surgical resection of tumors. These miRNAs were also secreted at significantly higher levels by colon cancer cell lines than by a normal colon-derived cell line. The high sensitivities of the seven selected exosomal miRNAs were confirmed by a receiver operating characteristic analysis.


CONCLUSIONS
Exosomal miRNA signatures appear to mirror pathological changes of CRC patients and several miRNAs are promising biomarkers for non-invasive diagnosis of the disease.
Division of Genome Biology, National Cancer Center Research Institute, Tokyo, Japan.
Hiroko
H
Ogata-Kawata
Department of Gastroenterology, The University of Tokyo Hospital, Tokyo, Japan.
Masashi
M
Izumiya
Division of Genome Biology, National Cancer Center Research Institute, Tokyo, Japan; Laboratory for Medical Engineering, Division of Materials and Chemical Engineering, Graduate School of Engineering, Yokohama National University, Kanagawa, Japan.
Daisuke
D
Kurioka
Gastrointestinal Oncology Division, National Cancer Center Hospital, Tokyo, Japan.
Yoshitaka
Y
Honma
Gastrointestinal Oncology Division, National Cancer Center Hospital, Tokyo, Japan.
Yasuhide
Y
Yamada
Division of Clinical Laboratories, National Cancer Center Hospital, Tokyo, Japan.
Koh
K
Furuta
NTT Medical Center Tokyo, Tokyo, Japan.
Toshiaki
T
Gunji
Shionogi & Co., Ltd., Osaka, Japan.
Hideki
H
Ohta
Shionogi & Co., Ltd., Osaka, Japan.
Hiroyuki
H
Okamoto
Shionogi & Co., Ltd., Osaka, Japan.
Hikaru
H
Sonoda
Laboratory for Medical Engineering, Division of Materials and Chemical Engineering, Graduate School of Engineering, Yokohama National University, Kanagawa, Japan.
Masatoshi
M
Watanabe
Division of Cancer Development System, National Cancer Center Research Institute, Tokyo, Japan.
Hitoshi
H
Nakagama
Division of Genome Biology, National Cancer Center Research Institute, Tokyo, Japan; Institute of Predictive and Personalized Medicine of Cancer (IMPPC), Barcelona, Spain.
Jun
J
Yokota
Division of Genome Biology, National Cancer Center Research Institute, Tokyo, Japan.
Takashi
T
Kohno
Division of Genome Biology, National Cancer Center Research Institute, Tokyo, Japan.
Naoto
N
Tsuchiya
D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood / Q000235:genetics*; D016022:Case-Control Studies; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000097:blood / Q000235:genetics*; D055354:Exosomes / Q000235:genetics* / Q000473:pathology; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D045325:HCT116 Cells; D019073:HT29 Cells; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000097:blood*; D046228:Microarray Analysis; D008875:Middle Aged; D014407:Tumor Cells, Cultured
D014408:Biomarkers, Tumor; D035683:MicroRNAs