Abstract 867: Serum microRNAs as diagnostic biomarkers for early colorectal neoplasms
Authors: Yamada Atsushi , Horimatsu Takahiro , Okugawa Yoshinaga , Nishida Naoshi , Kou Tadayuki , Kusaka Toshihiro , Honjo Hajime , Amanuma Yusuke , Kikuchi Osamu , Muto Manabu , Goel Ajay , Boland C. Richard 
Published: May 2015

Objectives: Early detection of precancerous lesions and early-stage cancers are essential to reduce mortality from colorectal cancer (CRC).

Serum/plasma microRNAs (miRs) have been reported as diagnostic and prognostic biomarkers of CRC, but their utility in detecting patients with early lesions has not been fully explored. The aim of this study is to identify serum miRs which are potentially useful as diagnostic biomarkers for early colorectal neoplasms, and potential confounders in a blood test.

Methods: Candidate biomarker miRs were selected from previously published studies. Serum samples were collected from patients with low-grade intraepithelial neoplasias (LGINs) including tubular adenomas and tubulovillous adenomas, high-grade intraepithelial neoplasias (HGINs), early cancers, and healthy volunteers, and divided into discovery and validation sets. Total RNA was extracted from serum samples and levels of candidate miRs were measured by real-time RT-PCR. To evaluate the impact of hemolysis on serum miR levels, serially diluted hemolysed controls were prepared from stock solution made by hemolysing the red blood cells in distilled water. Levels of candidate miRs in hemolysed controls were also examined by real-time RT-PCR. Absorbance of serum samples at 560 nm, 576 nm, and 592 nm was measured by spectrophotometry and hemoglobin levels were estimated from a standard curve.

Results: Fourteen miRs were selected as candidate diagnostic biomarkers of early colorectal neoplasms from a review of the literature. Serum levels of five miRs were too low to be accurately quantified by real-time RT-PCR, and excluded from further evaluation. Sera from 12 patients with LGINs, 8 patients with HGINs, 4 patients with cancers, and 25 healthy volunteers were included in the discovery phase. Of 9 miRs examined, miR21 (p = 0.0007), miR29a (p &lt; 0.0001) and miR125b (p = 0.0198) showed significantly higher levels in sera from early colorectal neoplasms compared to those from healthy volunteers. Higher levels of miR29a and miR125b in sera from early colorectal neoplasms were confirmed in the validation phase using independent set of samples. Levels of miR21, 29a, and miR125b in sera significantly correlated with the degree of hemolysis.

Conclusions: Serum miRs may be useful biomarkers to detect patients with early colorectal neoplasia, including adenomas. Hemolysis affects serum miR levels, and will confound measurement. Since hemolysis occurs frequently during blood collection, its impact on serum miRs should be further investigated.

Citation Format: Atsushi Yamada, Takahiro Horimatsu, Yoshinaga Okugawa, Naoshi Nishida, Tadayuki Kou, Toshihiro Kusaka, Hajime Honjo, Yusuke Amanuma, Osamu Kikuchi, Manabu Muto, Ajay Goel, C. Richard Boland. Serum microRNAs as diagnostic biomarkers for early colorectal neoplasms. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 867. doi:10.1158/1538-7445.AM2014-867