Basic Study
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. May 28, 2015; 21(20): 6167-6179
Published online May 28, 2015. doi: 10.3748/wjg.v21.i20.6167
Insights into glycan biosynthesis in chemically-induced hepatocellular carcinoma in rats: A glycomic analysis
Amr Amin, Asma Bashir, Nazar Zaki, Diane McCarthy, Sanjida Ahmed, Mohamed Lotfy
Amr Amin, Asma Bashir, Mohamed Lotfy, Department of Biology, College of Science, UAE University, Al-Ain 15551, United Arab Emirates
Amr Amin, Zoology Department, Faculty of Science, Cairo University, Cairo 12613, Egypt
Nazar Zaki, Intelligent Systems, College of Information Technology, UAE University, Al-Ain 17551, United Arab Emirates
Diane McCarthy, Ezose Sciences Inc., Pine Brook, NJ 07058, United States
Sanjida Ahmed, Eastern Biotech and Life Sciences, Dubai 212671, United Arab Emirates
Mohamed Lotfy, Hormones Department, National Research Center, Cairo 12622, Egypt
Author contributions: Amin A designed the study, supervised the experimental work, interpreted the data and helped to write the manuscript; Bashir A helped in data interpretation, writing the manuscript and in the presentation of some figures; Bashir A performed the t-test statistical analysis; Zaki N helped with data interpretation; McCarthy D performed the glycomic experiment, helped in writing the manuscript and in the presentation of some figures; Lotfy M shared in the statistical analysis; all authors read and approved the final manuscript.
Supported by National Research Foundation Grant No. UIRCA 2012-21832 for A. Amin.
Ethics approval: The study was reviewed and approved by UAE University No.1185/10.
Institutional animal care and use committee: All procedures involving animals were reviewed and approved by the Institutional Animal Care and Use Committee of the UAE University (Ethics approval No.1185/10).
Conflict-of-interest: No potential conflicts of interest relevant to this article were reported.
Data sharing: Technical appendix, statistical code, and dataset available from the corresponding author at (a.amin@uaeu.ac.ae).
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: Amr Amin, PhD, Professor, Department of Biology, College of Science, UAE University, University Street, Al-Ain 15551, United Arab Emirates. a.amin@uaeu.ac.ae
Telephone: +97-13-7136519 Fax: +97-13-7134927
Received: November 26, 2014
Peer-review started: November 27, 2014
First decision: December 26, 2014
Revised: January 19, 2015
Accepted: February 12, 2015
Article in press: February 13, 2015
Published online: May 28, 2015
Processing time: 184 Days and 17 Hours
Abstract

AIM: To evaluate the qualitative and quantitative changes in N-linked glycosylation, which occurred in association with diethyl nitrosamine-induced hepatocellular carcinoma (HCC) in rodents.

METHODS: Liver tissues of (1) normal (non-tumor-bearing) rats; and (2) tumor-bearing rats; were collected and were used for histological and GlycanMap® analyses. Briefly, GlycanMap® analysis is a high-throughput assay that provides a structural and quantitative readout of protein-associated glycans using a unique, automated 96-well assay technology coupled to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and custom bioinformatics. Histopathological studies were carried out to ensure the development of HCC in the tested animals.

RESULTS: The N-glycomic analysis revealed 5 glycans; Glc1Man9GlcNAc2, Gal2Man3GlcNac4Fuc1Neu1, Man4GlcNac2, Gal2Man3GlcNac4Neu3OAc3, and Man3GlcNac5Fuc1, which showed significant changes in rat HCC tissues when compared with normal liver tissues. Four glycans were increased (P < 0.05) and Glc1Man9GlcNAc2 was decreased (5.89 ± 0.45 vs 3.54 ± 0.21, P < 0.01) in HCC tissues compared to normal liver tissues. An increase (66.5 ± 1.05 vs 62.7 ± 1.1, P < 0.05) in high-mannose structures in HCC rats was observed compared to normal rats. Importantly, HCC rats showed an increase (P < 0.05) in both tumor-associated carbohydrates and in branched glycans. The changes in glycans correlated well with glycan flow changes reported in the glycan biosynthetic pathway, which indicates the importance of enzyme activities involved in glycan synthesis at different subcellular localizations.

CONCLUSION: The reported HCC-associated changes in glycan flow and subcellular localization explain the increase in high mannose glycans and siayl Lewis glycans common in HCC liver tissues.

Keywords: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry; Hepatocellular carcinoma; Glycomics; Biosynthetic pathways

Core tip: Hepatocellular carcinoma (HCC) is a leading cause of cancer death worldwide, yet it is still poorly diagnosed. Glycans are emerging as sensitive and simple biomarkers of various malignant diseases. Utilizing the cutting-edge N-glycomic analysis, we identified 5 glycans that were significantly different between normal and tumor-bearing rats. An increase in high-mannose structures in HCC rats was observed compared to normal rats. HCC rats showed an increase in both tumor-associated carbohydrates and branched glycans. The changes in glycans correlated with glycan flow changes reported in the glycan biosynthetic pathway, which indicates the importance of enzyme activities involved in glycan synthesis at different subcellular localizations.