Copyright ©The Author(s) 2019. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Sep 14, 2019; 25(34): 5026-5048
Published online Sep 14, 2019. doi: 10.3748/wjg.v25.i34.5026
Diagnostic and prognostic potential of tissue and circulating long non-coding RNAs in colorectal tumors
Orsolya Galamb, Barbara K Barták, Alexandra Kalmár, Zsófia B Nagy, Krisztina A Szigeti, Zsolt Tulassay, Peter Igaz, Béla Molnár
Orsolya Galamb, Alexandra Kalmár, Zsolt Tulassay, Peter Igaz, Béla Molnár, Molecular Medicine Research Group, Hungarian Academy of Sciences, Budapest H-1088, Hungary
Barbara K Barták, Zsófia B Nagy, Krisztina A Szigeti, Peter Igaz, 2nd Department of Internal Medicine, Semmelweis University, Budapest H-1088, Hungary
Author contributions: All authors contributed to this paper with conception and design of the study, literature review and analysis, drafting and critical revision and editing, and final approval of the final version.
Supported by the National Research, Development and Innovation Office, No. NVKP_16-1-2016-0004.
Conflict-of-interest statement: The authors declare that no conflict of interest exist.
Open-Access: This is an open-access article that 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:
Corresponding author: Orsolya Galamb, MSc, PhD, Research Fellow, Senior Scientist, 2nd Department of Internal Medicine, Semmelweis University, Szentkirályi Str 46, Budapest H-1088, Hungary.
Telephone: +36-1-2660926 Fax: +36-1-2660816
Received: June 25, 2019
Peer-review started: June 25, 2019
First decision: July 21, 2019
Revised: July 26, 2019
Accepted: August 7, 2019
Article in press: August 7, 2019
Published online: September 14, 2019

Long non-coding RNAs (lncRNAs) are members of the non-protein coding RNA family longer than 200 nucleotides. They participate in the regulation of gene and protein expression influencing apoptosis, cell proliferation and immune responses, thereby playing a critical role in the development and progression of various cancers, including colorectal cancer (CRC). As CRC is one of the most frequently diagnosed malignancies worldwide with high mortality, its screening and early detection are crucial, so the identification of disease-specific biomarkers is necessary. LncRNAs are promising candidates as they are involved in carcinogenesis, and certain lncRNAs (e.g., CCAT1, CRNDE, CRCAL1-4) show altered expression in adenomas, making them potential early diagnostic markers. In addition to being useful as tissue-specific markers, analysis of circulating lncRNAs (e.g., CCAT1, CCAT2, BLACAT1, CRNDE, NEAT1, UCA1) in peripheral blood offers the possibility to establish minimally invasive, liquid biopsy-based diagnostic tests. This review article aims to describe the origin, structure, and functions of lncRNAs and to discuss their contribution to CRC development. Moreover, our purpose is to summarise lncRNAs showing altered expression levels during tumor formation in both colon tissue and plasma/serum samples and to demonstrate their clinical implications as diagnostic or prognostic biomarkers for CRC.

Keywords: Long non-coding RNA, Colorectal cancer, Colorectal adenoma, Circulating long non-coding RNAs, Exosome, Biomarker, Diagnostic marker, Prognostic marker

Core tip: The present review aims to shed light on the complex world of long non-coding RNAs (lncRNAs) by discussing their origin, localization, and functions. By summarizing the constantly growing body of knowledge about lncRNA expression in colorectal tissue and by focusing on potential circulating lncRNA markers, we aim to enhance the understanding of the comprehensive picture of their diagnostic and prognostic potential in precancerous colorectal adenomas and cancer.