Basic Study
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Aug 7, 2015; 21(29): 8836-8847
Published online Aug 7, 2015. doi: 10.3748/wjg.v21.i29.8836
Upregulation of nemo-like kinase is an independent prognostic factor in colorectal cancer
Wei Zhang, Jian He, Yan Du, Xian-Hua Gao, Yan Liu, Qi-Zhi Liu, Wen-Jun Chang, Guang-Wen Cao, Chuan-Gang Fu
Wei Zhang, Jian He, Xian-Hua Gao, Qi-Zhi Liu, Chuan-Gang Fu, Department of Colorectal Surgery, Changhai Hospital, The Second Military Medical University, Shanghai 200433, China
Yan Du, Yan Liu, Wen-Jun Chang, Guang-Wen Cao, Department of Epidemiology, The Second Military Medical University, Shanghai 200433, China
Author contributions: Zhang W, He J, Du Y and Gao XH contributed equally to this work; Zhang W and Fu CG designed research; Zhang W, He J, Du Y, Gao XH, Liu Y and Liu QZ performed research; He J and Gao XH analyzed data; Zhang W and Du Y wrote the paper; Chang WJ, Cao GW and Fu CG revised the manuscript.
Supported by National Natural Science Foundation of China, No. 81272670, No. 81201936 and No. 81025015.
Institutional review board statement: The study was reviewed and approved by the Ethics Committee of Shanghai Changhai Hospital, Second Military Medical University.
Conflict-of-interest statement: There is no conflict of interest in this study.
Data sharing statement: Technical appendix, statistical code, and dataset available from the corresponding author at fugang416@126.com. Participants gave informed consent for data sharing.
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: Chuan-Gang Fu, MD, PhD, Professor, Department of Colorectal Surgery, Changhai Hospital, The Second Military Medical University, No. 168 Changhai Road, Shanghai 200433, China. fugang416@126.com
Telephone: +86-21-31161601 Fax: +86-21-31161601
Received: January 2, 2015
Peer-review started: January 3, 2015
First decision: January 22, 2015
Revised: February 14, 2015
Accepted: March 27, 2015
Article in press: March 27, 2015
Published online: August 7, 2015
Processing time: 217 Days and 17.9 Hours
Abstract

AIM: To investigate the expression and oncogenic role of nemo-like kinase (NLK) in colorectal cancer.

METHODS: Expression of NLK protein was assessed by immunohistochemistry in tissue specimens from 56 cases of normal colorectal mucosa, 51 cases of colorectal adenoma, and 712 cases of colorectal cancer. In addition, NLK expression was knocked down using a lentivirus carrying NLK small hairpin RNA in colorectal cancer cells. Cell viability methylthiazoletetrazolium assays, colony formation assays, flow cytometry cell cycle assays, Transwell migration assays, and gene expression assays were performed to explore its role on proliferation and migration of colorectal cancer.

RESULTS: Expression of NLK protein progressively increased in tissues from the normal mucosa through adenoma to various stages of colorectal cancer. Overexpression of NLK protein was associated with advanced tumor-lymph node-metastasis stages, poor differentiation, lymph node and distant metastases, and a higher recurrence rate of colorectal cancer (P < 0.05). Multivariate analyses showed that NLK expression was an independent prognostic factor to predict overall survival (hazard ratio 2.57, 95% confidence interval: 1.66-3.98; P < 0.001) and disease-free survival (hazard ratio 1.96, 95% confidence interval: 1.40-2.74: P < 0.001) of colorectal cancer patients. Furthermore, knockdown of NLK expression in colorectal cancer cell lines reduced cell viability, colony formation, and migration, and arrested tumor cells at the G0/G1 phase of the cell cycle. At the gene level, knockdown of NLK expression inhibited matrix metalloproteinase-2 expression in colorectal cancer cells.

CONCLUSION: NLK overexpression is an independent prognostic factor in colorectal cancer and knockdown of NLK expression inhibits colorectal cancer progression and metastasis.

Keywords: Colorectal cancer; Gene regulation; Nemo-like kinase; Prognosis

Core tip: Altered expression of nemo-like kinase (NLK) protein is associated with cancer development. This study systematically evaluated NLK expression in different stages of colorectal cancer (CRC) for association with CRC prognosis. NLK expression progressively increased from normal tissues through adenoma, stage I, II, and III, to stage IV CRC. However, knockdown of NLK expression significantly inhibited CRC cell growth, migration, cell cycle progression, and matrix metalloproteinase-2 expression. These data demonstrate that NLK overexpression is an independent CRC prognostic indicator and that knockdown of NLK expression inhibits CRC cell progression and metastasis.