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Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jun 21, 2016; 22(23): 5317-5331
Published online Jun 21, 2016. doi: 10.3748/wjg.v22.i23.5317
MicroRNAs: Novel immunotherapeutic targets in colorectal carcinoma
Xiang Li, Jing Nie, Qian Mei, Wei-Dong Han
Xiang Li, Jing Nie, Qian Mei, Wei-Dong Han, Department of Molecular Biology, School of Life Sciences, Chinese PLA General Hospital, Beijing 100853, China
Author contributions: Li X searched the literature and contributed largely to the writing of the manuscript; Nie J contributed with her own opinions to this review and offered suggestions on the structure of this paper; Mei Q and Han WD contributed to the writing, reviewed all the versions of the manuscript, gave the final approval of the version to be published and revised this article for important intellectual content; Mei Q and Han WD are co-corresponding authors.
Supported by National Natural Science Foundation of China, No. 81272867 and No. 81572914; Beijing Nova Program, No. Z131107000413103.
Conflict-of-interest statement: Authors declare no conflict of interests for this article.
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:
Correspondence to: Wei-Dong Han, PhD, MD, Professor, Department of Molecular Biology, School of Life Sciences, Chinese PLA General Hospital, Beijing 100853, China.
Telephone: +86-10-66937463 Fax: +86-10-66937516
Received: March 24, 2016
Peer-review started: March 25, 2016
First decision: April 14, 2016
Revised: April 23, 2016
Accepted: May 4, 2016
Article in press: May 4, 2016
Published online: June 21, 2016

Colorectal carcinoma (CRC) is one of the most common types of cancer worldwide and the prognosis for CRC patients with recurrence or metastasis is extremely poor. Although chemotherapy and radiation therapy can improve survival, there are still numerous efforts to be performed. Immunotherapy is frequently used, either alone or in combination with other therapies, for the treatment of CRC and is a safe and feasible way to improve CRC treatment. Furthermore, the significance of the immune system in the biology of CRC has been demonstrated by retrospective assessments of immune infiltrates in resected CRC tumors. MicroRNAs (miRNAs) are short, non-coding RNAs that can regulate multiple target genes at the post-transcriptional level and play critical roles in cell proliferation, differentiation and apoptosis. MiRNAs are required for normal immune system development and function. Nevertheless, aberrant expression of miRNAs is often observed in various tumor types and leads to immune disorders or immune evasion. The immunomodulatory function of miRNAs indicates that miRNAs may ultimately be part of the portfolio of anti-cancer targets. Herein, we will review the potential roles of miRNAs in the regulation of the immune response in CRC and then move on to discuss how to utilize different miRNA targets to treat CRC. We also provide an overview of the major limitations and challenges of using miRNAs as immunotherapeutic targets.

Keywords: Colorectal carcinoma, microRNAs, Tumor microenvironment, Immunotherapy, Inflammation, Inflammatory bowel disease, Immune response

Core tip: Colorectal carcinoma (CRC) is one of the most common tumor types worldwide. Immunotherapy has been used to treat advanced CRC and has the potential to eradicate the disease by activating immune responses. MicroRNAs play critical roles in regulating anti-tumor immune responses. There is a need to summarize the current understanding of the diverse roles of microRNAs in the regulation of immune responses and their clinical applications for CRC immunotherapy.