Basic Study
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Sep 14, 2015; 21(34): 9916-9926
Published online Sep 14, 2015. doi: 10.3748/wjg.v21.i34.9916
Macrophage migration inhibitory factor as a potential prognostic factor in gastric cancer
Long-Jun He, Dan Xie, Pin-Jin Hu, Yi-Ji Liao, Hai-Xia Deng, Hsiang-Fu Kung, Sen-Lin Zhu
Long-Jun He, Pin-Jin Hu, Sen-Lin Zhu, Department of Gastroenterology, the First Affiliated Hospital, Sun Yat-sen University, Guangzhou 510080, Guangdong Province, China
Long-Jun He, Dan Xie, Yi-Ji Liao, Hai-Xia Deng, Sun Yat-sen University Cancer Center; State Key Laboratory of Oncology in South China; Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, Guangdong Province, China
Hsiang-Fu Kung, Stanley Ho Center for Emerging Infectious Diseases and Li Ka Shing Institute of Health Sciences, Hong Kong, China
Hsiang-Fu Kung, State Key Laboratory of Oncology in South China, The Chinese university of Hong Kong, Hong Kong, China
Author contributions: Zhu SL designed the study and was the project leader; He LJ and Liao YJ performed the experiments; Hu PJ and Deng HX collected the data; Xie D and Kung HF served as scientific advisors.
Supported by Grants from the National Natural Science Foundation of China, No. 81072044; and the Guangdong Natural Science Foundation, No. S2011010004653.
Institutional review board statement: The study was reviewed and approved by the Medical Ethics Committee of the First Affiliated Hospital, Sun Yat-sen Univeristy.
Conflict-of-interest statement: Participants have received no fees or funds from outside organizations except this study’s own research funding. No participants own stocks or shares in study-related organizations.
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: Dr. Sen-Lin Zhu, Department of Gastroenterology, the First Affiliated Hospital, Sun Yat-sen University, No. 58 Zhongshan 2nd Road, Guangzhou 510080, Guangdong Province, China. zhusl@mail.sysu.edu.cn
Telephone: +86-20-87332200
Received: February 23, 2015
Peer-review started: February 26, 2015
First decision: March 26, 2015
Revised: April 13, 2015
Accepted: July 15, 2015
Article in press: July 15, 2015
Published online: September 14, 2015
Abstract

AIM: To investigate macrophage migration inhibitory factor (MIF) expression and its clinical relevance in gastric cancer, and effects of MIF knockdown on proliferation of gastric cancer cells.

METHODS: Tissue microarray containing 117 samples of gastric cancer and adjacent non-cancer normal tissues was studied for MIF expression by immunohistochemistry (IHC) semiquantitatively, and the association of MIF expression with clinical parameters was analyzed. MIF expression in gastric cancer cell lines was detected by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. Two pairs of siRNA targeting the MIF gene (MIF si-1 and MIF si-2) and one pair of scrambled siRNA as a negative control (NC) were designed and chemically synthesized. All siRNAs were transiently transfected in AGS cells with OligofectamineTM to knock down the MIF expression, with the NC group and mock group (OligofectamineTM alone) as controls. At 24, 48, and 72 h after transfection, MIF mRNA was analyzed by RT-PCR, and MIF and proliferating cell nuclear antigen (PCNA) proteins were detected by Western blot. The proliferative rate of AGS cells was assessed by methylthiazolyl tetrazolium (MTT) assay and colony forming assay.

RESULTS: The tissue microarray was informative for IHC staining, in which the MIF expression in gastric cancer tissues was higher than that in adjacent non-cancer normal tissues (P < 0.001), and high level of MIF was related to poor tumor differentiation, advanced T stage, advanced tumor stage, lymph node metastasis, and poor patient survival (P < 0.05 for all). After siRNA transfection, MIF mRNA was measured by real-time PCR, and MIF protein and PCNA were assessed by Western blot analysis. We found that compared to the NC group and mock group, MIF expression was knocked down successfully in gastric cancer cells, and PCNA expression was downregulated with MIF knockdown as well. The cell counts and the doubling times were assayed by MTT 4 d after transfection, and colonies formed were assayed by colony forming assay 10 d after transfection; all these showed significant changes in gastric cancer cells transfected with specific siRNA compared with the control siRNA and mock groups (P < 0.001 for all).

CONCLUSION: MIF could be of prognostic value in gastric cancer and might be a potential target for small-molecule therapy.

Keywords: Macrophage migration inhibitory factor, Proliferation, RNA interference, Stomach neoplasm, Survival

Core tip: Macrophage migration inhibitory factor (MIF) is a multifunctional cytokine, which plays a significant role in the tumor development. The objective of this study was to investigate the expression of MIF in gastric cancer and the inhibitory effect of its knockdown on gastric cancer cell proliferation. The results show that MIF is expressed highly in gastric cancer, and its expression was related to clinical stage. The proliferation of gastric cancer cells was inhibited by MIF knockdown, suggesting that MIF is a potential target in molecular therapy for gastric cancer.