Circulating exosomal microRNAs as biomarkers of colon cancer

PLoS One. 2014 Apr 4;9(4):e92921. doi: 10.1371/journal.pone.0092921. eCollection 2014.

Abstract

Purpose: 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.

Experimental design: 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.

Conclusion: Exosomal miRNA signatures appear to mirror pathological changes of CRC patients and several miRNAs are promising biomarkers for non-invasive diagnosis of the disease.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Biomarkers, Tumor / blood
  • Biomarkers, Tumor / genetics*
  • Case-Control Studies
  • Cell Line, Tumor
  • Colonic Neoplasms / blood
  • Colonic Neoplasms / genetics*
  • Exosomes / genetics*
  • Exosomes / pathology
  • Female
  • Gene Expression Profiling
  • Gene Expression Regulation, Neoplastic
  • HCT116 Cells
  • HT29 Cells
  • Humans
  • Male
  • MicroRNAs / blood*
  • Microarray Analysis
  • Middle Aged
  • Tumor Cells, Cultured

Substances

  • Biomarkers, Tumor
  • MicroRNAs

Grant support

Funding provided by The Advanced Research for Medical Products Mining Program of the National Institute of Biomedical Innovation (NIBIO)(08-02), http://www.nibio.go.jp; Grant-in-Aids from the Ministry of Health, Labor and Welfare (13802015), http://www.mhlw.go.jp/; Grant-in-Aids from the Ministry of Education, Culture, Sports & Technology of Japan (13314780), http://www.jsps.go.jp/; National Cancer Center Research and Development Fund (23-B-08), http://www.ncc.go.jp. National Cancer Center Biobank is supported by National Cancer Center Research and Development Fund. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.