Basic Study
Copyright ©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Dec 21, 2017; 23(47): 8291-8299
Published online Dec 21, 2017. doi: 10.3748/wjg.v23.i47.8291
Gene mutations in stool from gastric and colorectal neoplasia patients by next-generation sequencing
Omar Youssef, Virinder Sarhadi, Homa Ehsan, Tom Böhling, Monika Carpelan-Holmström, Selja Koskensalo, Pauli Puolakkainen, Arto Kokkola, Sakari Knuutila
Omar Youssef, Virinder Sarhadi, Homa Ehsan, Sakari Knuutila, Department of Pathology, Faculty of Medicine, University of Helsinki, Helsinki 00014, Finland
Tom Böhling, Department of Pathology, University of Helsinki and HUSLAB, Helsinki University Hospital, Helsinki 00014, Finland
Monika Carpelan-Holmström, Selja Koskensalo, Pauli Puolakkainen, Arto Kokkola, The HUCH Gastrointestinal Clinic, University Central Hospital of Helsinki, Helsinki 00290, Finland
Author contributions: Youssef O conducted sequencing of the samples and prepared the manuscript; Ehsan H prepared the samples for sequencing; Kokkola A, Carpelan-Holmström M, Koskensalo S and Puolakkainen P contributed clinical support for the participating subjects and arranged for stool sample collection; Sarhadi V, Böhling T and Knuutila S contributed to the study design and writing of the manuscript.
Institutional review board statement: The research study protocol was approved by the Hospital District of Helsinki and Uusimaa (HUS) Review Board (Ethical permission number 351/13/03/02/2014).
Conflict-of-interest statement: The authors declare no conflicts of interest.
Data sharing statement: Dataset available from sakari.knuutila@helsinki.fi
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Sakari Knuutila, PhD, Professor, Department of Pathology, Faculty of Medicine, University of Helsinki, Haartmaninkatu 4, Helsinki 00014, Finland. sakari.knuutila@helsinki.fi
Telephone: +358-504482797 Fax: +358-294126700
Received: October 3, 2017
Peer-review started: October 5, 2017
First decision: October 18, 2017
Revised: November 1, 2017
Accepted: November 14, 2017
Article in press: November 14, 2017
Published online: December 21, 2017
Processing time: 77 Days and 16.8 Hours
Abstract
AIM

To study cancer hotspot mutations by next-generation sequencing (NGS) in stool DNA from patients with different gastrointestinal tract (GIT) neoplasms.

METHODS

Stool samples were collected from 87 Finnish patients diagnosed with various gastric and colorectal neoplasms, including benign tumors, and from 14 healthy controls. DNA was isolated from stools by using the PSP® Spin Stool DNA Plus Kit. For each sample, 20 ng of DNA was used to construct sequencing libraries using the Ion AmpliSeq Cancer Hotspot Panel v2 or Ion AmpliSeq Colon and Lung Cancer panel v2. Sequencing was performed on Ion PGM. Torrent Suite Software v.5.2.2 was used for variant calling and data analysis.

RESULTS

NGS was successful in assaying 72 GIT samples and 13 healthy controls, with success rates of the assay being 78% for stomach neoplasia and 87% for colorectal tumors. In stool specimens from patients with gastric neoplasia, five hotspot mutations were found in APC, CDKN2A and EGFR genes, in addition to seven novel mutations. From colorectal patients, 20 mutations were detected in AKT1, APC, ERBB2, FBXW7, KIT, KRAS, NRAS, SMARCB1, SMO, STK11 and TP53. Healthy controls did not exhibit any hotspot mutations, except for two novel ones. APC and TP53 were the most frequently mutated genes in colorectal neoplasms, with five mutations, followed by KRAS with two mutations. APC was the most commonly mutated gene in stools of patients with premalignant/benign GIT lesions.

CONCLUSION

Our results show that in addition to colorectal neoplasms, mutations can also be assayed from stool specimens of patients with gastric neoplasms.

Keywords: Stool DNA; Next-generation sequencing; Mutations; Gastric neoplasia; Colorectal neoplasia

Core tip: Next-generation sequencing (NGS) was successfully applied for detecting cancer gene mutations in stool DNA of patients with different gastrointestinal neoplasms. Using a gene panel, comprising up to 50 cancer genes, it was found that mutations not only could be detected in stool DNA from colorectal cancer patients but also in patients with stomach cancer and those with benign or premalignant lesions. No hotspot mutations were detected in healthy controls. Our results show that NGS could be useful in screening for neoplastic changes of the gastrointestinal tract.