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©The Author(s) 2021. Published by Baishideng Publishing Group Inc. All rights reserved.
Direct interaction between Rab5a and Rab4a enhanced epidermal growth factor-stimulated proliferation of gastric cancer cells
Guo-Jun Cao, Di Wang, Zhao-Pei Zeng, Guo-Xiang Wang, Chun-Jiu Hu, Zhi-Fang Xing
Guo-Jun Cao, Di Wang, Department of Laboratory Medicine, Huashan Hospital North, Shanghai Medical College, Fudan University, Shanghai 201907, China
Di Wang, School of Life Sciences, Fudan University, Shanghai 200433, China
Zhao-Pei Zeng, Department of Laboratory Medicine, Diniu (Shanghai) Health Technology Co., Shanghai 201703, China
Guo-Xiang Wang, Department of Neurology, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institute of Biological Science, Zhongshan Hospital, Fudan University, Shanghai 200032, China
Chun-Jiu Hu, Department of Gastroenterology, Ningbo First Hospital, Ningbo 315000, Zhejiang Province, China
Zhi-Fang Xing, Department of Laboratory Medicine, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai 200040, China
Author contributions: Cao GJ and Wang D contributed equally to this work and are joint first authors; Xing ZF and Wang GX contributed equally to the supervision of the study and share co-senior authorship; Cao GJ carried out western blot and co-immunoprecipitation experiments and helped with the experimental design; Wang D was the main writer of this manuscript and took part in the planning and execution of the immunostaining and co-immunoprecipitation experiments; Zeng ZP also wrote the main part of the manuscript and took part in the analysis of the data; Hu CJ participated in the coordination of the study and reviewed the manuscript; Wang GX contributed to experimental design and data analysis; Xing ZF helped with the experimental design and implementation of this research.
Supported by The Shanghai Health and Family Planning Commission, No. 20154Y0141; Shanghai "Rising Stars of Medical Talent" Youth Development Program (Youth Medical Talents – Clinical Laboratory Practitioners Program); and the Project of Huashan Hospital North, Fudan University, No. HSBY2019020.
Institutional review board statement: The study was reviewed and approved by the Minhang Center Hospital, Fudan University Institutional Review Board (2015 No. 42).
Conflict-of-interest statement: We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product.
Data sharing statement: No additional unpublished data are available.
Open-Access: This article 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 NonCommercial (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/ Corresponding author: Zhi-Fang Xing, Department of Laboratory Medicine, Huashan Hospital, Shanghai Medical College, Fudan University, No. 12 Middle Urumqi Road, Shanghai 200040, China. xzfisme@163.com
Received: January 28, 2021
Peer-review started: January 28, 2021
First decision: June 4, 2021
Revised: June 16, 2021
Accepted: July 14, 2021
Article in press: July 14, 2021
Published online: October 15, 2021
BACKGROUND
Gastric cancer (GC) is one of the leading causes of cancer-related death worldwide. Although targeted therapies such as antibodies against human epidermal growth factor receptor 2 or vascular endothelial growth factor receptor 2 have been widely used in the treatment of metastatic cancer, the overall outcomes are poor. Therefore, elucidation of the mechanism underlying cancer progression is important to improve prognosis. Overexpression of the Rab5a gene has been confirmed to correlate with tumorigenesis of many cancers, but the mechanism underling, especially of GC, is still unclear.
AIM
To investigate the effects of Rab5a overexpression on the tumorigenesis of GC.
METHODS
First, the expression levels of Rab5a and Rab4a in primary tumorous tissues of GC patients diagnosed between 2015 and 2018 were analyzed. Then we constructed HGC-27 cell lines overexpressing green fluorescent protein-Rab5a or red fluorescent protein-Rab4a and investigated the interaction between Rab5a or Rab4a using Western blotting, co-immunoprecipitation, confocal microscopy, and colocalization analysis. Finally, epidermal growth factor-stimulated proliferation of these cell lines was analyzed using cell counting kit-8 cell viability assay.
RESULTS
Compared with normal gastric tissues, the expression levels of Rab5a and Rab4a increased progressively both in paracancerous tissues and in advanced cancerous tissues. Epidermal growth factor could promote the proliferation of HGC-27 cells, especially Rab5a-overexpressing HGC-27 cells. Notably, Rab5a and Rab4a co-overexpression promoted the proliferation of HGC-27 cells to the greatest extent. Further analysis identified a direct interaction between Rab5a and Rab4a in HGC-27 cells.
CONCLUSION
Co-overexpression of Rab5a and Rab4a in GC may promote the endosomal recycling of epidermal growth factor receptor, which in turn contributes to poor prognosis and tumor progression in GC patients. Inhibition of Rab5a or Rab4a expression might be a promising therapy for refractory GC.
Core Tip: Firstly, our data proved that Rab5a can directly interact with Rab4a. Secondly, our study provided evidence that increased level of Rab5a can promote the expression of Rab4a, but increased Rab4a expression does not significantly affect Rab5a level. Lastly, our study suggests that the interaction between Rab5a and Rab4a is important for enhanced epidermal growth factor receptor expression on the cell membrane surface, which facilitates epidermal growth factor-stimulated proliferation of gastric cancer cells.
