Basic Study
Copyright ©The Author(s) 2018. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Sep 14, 2018; 24(34): 3861-3870
Published online Sep 14, 2018. doi: 10.3748/wjg.v24.i34.3861
Delta-like ligand 4 in hepatocellular carcinoma intrinsically promotes tumour growth and suppresses hepatitis B virus replication
Areerat Kunanopparat, Jiraphorn Issara-Amphorn, Asada Leelahavanichkul, Anapat Sanpavat, Suthiluk Patumraj, Pisit Tangkijvanich, Tanapat Palaga, Nattiya Hirankarn
Areerat Kunanopparat, Jiraphorn Issara-Amphorn, Asada Leelahavanichkul, Nattiya Hirankarn, Center of Excellence in Immunology and Immune Mediated Diseases, Department of Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand
Anapat Sanpavat, Department of Pathology, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand
Suthiluk Patumraj, Center of Excellence for Microcirculation, Department of Physiology, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand
Pisit Tangkijvanich, Research Unit of Hepatitis and Liver Cancer, Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand
Tanapat Palaga, Department of Microbiology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
Author contributions: Kunanopparat A, Palaga T and Hirankarn N conceived and designed experiments; Kunanopparat A, Issara-Amphorn J, Leelahavanichkul A, Patumraj S and Tangkijvanich P conducted the experiments; Kunanopparat A and Sanpavat A analysed the data; Kunanopparat A, Palaga T and Hirankarn N wrote the manuscript.
Supported by National Research Council of Thailand 2013; the Ratchadaphiseksomphot Matching Fund from the Faculty of Medicine, Chulalongkorn University; the International Research Integration, Chula Research Scholar, Ratchadaphisek somphot Endowment Fund, Center of Excellence in Immunology and Immune-mediated Diseases; and the Rachadapisaek Sompote Post-Doctoral Fund, Chulalongkorn University.
Institutional review board statement: The study was approved by the Institutional Review Board of the Faculty of Medicine, Chulalongkorn University.
Institutional animal care and use committee statement: All protocols were carried out in accordance with relevant guidelines and regulations.
Conflict-of-interest statement: The authors declare no conflict of interest.
Data sharing statement: No additional data are available.
ARRIVE guidelines statement: The authors have read the ARRIVE guidelines, and the manuscript was prepared and revised according to the ARRIVE guidelines.
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: Nattiya Hirankarn, MD, PhD, Lecturer, Professor, Center of Excellence in Immunology and Immune Mediated Diseases Department of Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand. nattiya.H@chula.ac.th
Telephone: +66-2-2564132 Fax: +66-2-2525952
Received: May 25, 2018
Peer-review started: May 25, 2018
First decision: June 21, 2018
Revised: July 5, 2018
Accepted: July 16, 2018
Article in press: July 16, 2018
Published online: September 14, 2018
ARTICLE HIGHLIGHTS
Research background

Hepatitis B virus (HBV)-associated hepatocellular carcinoma (HCC) has been studied for many decades. However, the molecular mechanism is still unclear. Notch signaling in HCC pathogenesis is controversial, but we found that HBx promoted HBV-associated HCC proliferation through Delta-like ligand 4 (DLL4) (Notch ligand) in an in vitro study. However, the effect of DLL4 inhibition in HCC has not been explored.

Research motivation

DLL4 has a potential function for angiogenesis that supports tumour growth. The understanding of DLL4 mechanism might lead to identifying a new target for HCC therapy.

Research objective

We investigated the role of DLL4 on tumour growth in HCC associated with HBV in a xenograft model and detailed the molecular mechanism of HCC.

Research methods

We inhibited the DLL4 expression in HBV-associated HCC, and then subcutaneously implanted in nude mice. We analysed the ability for tumour growth, angiogenesis regulators (VEGF-A, VEGF-R2) expression, neovasculature, and HBV expression in tumour xenografts.

Research results

The tumour volume, VEGF-A, and VEGF-R2 were significantly decreased in mice implanted with suppressed DLL4 HCC compared with the control group. The suppression of DLL4 expression in tumour cells reduced cell proliferation and the formation of new blood vessels in tumours. Unexpectedly, viral replication increased in DLL4 suppressed tumours.

Research conclusions

This study demonstrates that DLL4 is important in regulating the tumour growth and neovascularization in HBV-associated HCC, as well as suppressing HBV replication in vivo.

Research perspective

This study showed that DLL4 is essential for the tumour growth of the implanted HBV-associated HCC cell line, especially in the initiation stage of tumour growth. However, the role of DLL4 as a tumour oncogene and tumour suppressor gene in HCC needs to further clarification.