Basic Study
Copyright ©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Aug 7, 2017; 23(29): 5345-5355
Published online Aug 7, 2017. doi: 10.3748/wjg.v23.i29.5345
PBX1 attributes as a determinant of connexin 32 downregulation in Helicobacter pylori-related gastric carcinogenesis
Xiao-Ming Liu, Can-Xia Xu, Lin-Fang Zhang, Li-Hua Huang, Ting-Zi Hu, Rong Li, Xiu-Juan Xia, Lin-Yong Xu, Ling Luo, Xiao-Xia Jiang, Ming Li
Xiao-Ming Liu, Can-Xia Xu, Lin-Fang Zhang, Ting-Zi Hu, Rong Li, Xiu-Juan Xia, Ling Luo, Xiao-Xia Jiang, Ming Li, Department of Gastroenterology, the Third Xiangya Hospital of Central South University, Changsha 410013, Hunan Province, China
Li-Hua Huang, Center for Medical Experiments, the Third Xiangya Hospital of Central South University, Changsha 410013, Hunan Province, China
Lin-Yong Xu, Department of Medical Statistics, Xiangya School of Public Health, Central South University, Changsha 410013, Hunan Province, China
Author contributions: Liu XM and Xu CX contributed to the conception and design of the study, as well as the acquisition, analysis and interpretation of data; Zhang LF, Hu TZ, Li R, Xia XJ, Luo L, Jiang XX and Li M performed the research; Huang LH contributed new reagents and analytic tools; Zhang LF and Xu LY analyzed the data; and Liu XM wrote the paper.
Supported by the New Xiangya Talent Project of the Third Xiangya Hospital of Central South University, No. 20150310.
Institutional review board statement: This study was reviewed and approved by the Ethics Committee of the Third Xiangya Hospital of Central South University.
Institutional animal care and use committee statement: All procedures involving animals were reviewed and approved by the Institutional Animal Care and Use Committee of the Third Xiangya Hospital of Central South University (A branch of the Ethics Committee of the Third Xiangya Hospital of Central South University, protocol number: 2017-S001).
Conflict-of-interest statement: The authors declare no conflicts of interest related to this manuscript.
Data sharing statement: No additional data are available.
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: Can-Xia Xu, MD, Professor of Gastroenterology, Department of Gastroenterology, the Third Xiangya Hospital of Central South University, No. 138 Tongzipo Street, Changsha 410013, Hunan Province, China. xucanxia2000@163.com
Telephone: +86-731-88618631 Fax: +86-731-88618012
Received: January 26, 2017
Peer-review started: February 2, 2017
First decision: March 17, 2017
Revised: April 25, 2017
Accepted: July 4, 2017
Article in press: July 4, 2017
Published online: August 7, 2017
Processing time: 192 Days and 19.1 Hours
Abstract
AIM

To clarify the mechanisms of connexin 32 (Cx32) downregulation by potential transcriptional factors (TFs) in Helicobacter pylori (H. pylori)-associated gastric carcinogenesis.

METHODS

Approximately 25 specimens at each developmental stage of gastric carcinogenesis [non-atrophic gastritis, chronic atrophic gastritis, intestinal metaplasia, dysplasia and gastric carcinoma (GC)] with H. pylori infection [H. pylori (+)] and 25 normal gastric mucosa (NGM) without H. pylori infection [H. pylori (-)] were collected. After transcriptional factor array analysis, the Cx32 and PBX1 expression levels of H. pylori-infected tissues from the developmental stages of GC and NGM with no H. pylori infection were measured by real-time polymerase chain reaction (RT-PCR) and Western blot analysis. Regarding H. pylori-infected animal models, the Cx32 and PBX1 mRNA expression levels and correlation between the gastric mucosa from 10 Mongolian gerbils with long-term H. pylori colonization and 10 controls were analyzed. PBX1 and Cx32 mRNA and protein levels were further studied under the H. pylori-infected condition as well as PBX1 overexpression and knockdown conditions in vitro.

RESULTS

Incremental PBX1 was first detected by TF microarray in H. pylori-related gastric carcinogenesis. The identical trend of PBX1 and Cx32 expression was confirmed in the developmental stages of H. pylori-related clinical specimens. The negative correlation of PBX1 and Cx32 was confirmed in H. pylori-infected Mongolian gerbils. Furthermore, decreased PBX1 expression was detected in the normal gastric epithelial cell line GES-1 with H. pylori infection. Enforced overexpression or RNAi-mediated knockdown of PBX1 contributed to the diminished or restored Cx32 expression in GES-1 and the gastric carcinoma cell line BGC823, respectively. Finally, dual-luciferase reporter assay in HEK293T cells showed that Cx32 promoter activity decreased by 30% after PBX1 vector co-transfection, indicating PBX1 as a transcriptional downregulator of Cx32 by directly binding to its promoters.

CONCLUSION

PBX1 is one of the determinants in the Cx32 promoter targeting site, preventing further damage of gap junction protein in H. pylori-associated gastric carcinogenesis.

Keywords: Helicobacter pylori; Inflammation-carcinoma chain; Connexin 32; PBX1; Carcinogenesis

Core tip: In this paper, we first report on the increasing tendency of transcriptional factor PBX1 in response to Helicobacter pylori (H. pylori) infection. This is significant because H. pylori is the predominant factor of gastric carcinoma, and the enhanced PBX1 expression in epithelial cells was first revealed as a marker of H. pylori-associated gastric carcinogenesis. Moreover, PBX1 transcriptionally downregulates the expression of connexin 32, which is vital to epithelial cell-cell communication, indicating an anti-cancer target that prevents the accumulation of PBX1 in the presence of H. pylori infection.