Basic Study
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Mar 21, 2015; 21(11): 3256-3265
Published online Mar 21, 2015. doi: 10.3748/wjg.v21.i11.3256
High-mobility group box 1 expression and lymph node metastasis in intrahepatic cholangiocarcinoma
Yun-Fei Xu, Fu-Jun Ge, Bo Han, Xiao-Qing Yang, Hong Su, An-Cheng Zhao, Ming-Hong Zhao, Yu-Bao Yang, Jie Yang
Yun-Fei Xu, Department of Hepatobilliary Surgery, Shandong University Qilu Hospital, Jinan 250012, Shandong Province, China
Fu-Jun Ge, Yu-Bao Yang, Department of General Surgery, Affiliated Hospital of Shandong Medical School, Linyi 276000, Shandong Province, China
Bo Han, Xiao-Qing Yang, Hong Su, Department of Pathology, Shandong University Medical School, Jinan 250012, Shandong Province, China
An-Cheng Zhao, Ming-Hong Zhao, Department of Clinical Laboratory, Yishui Central Hospital, Linyi 276000, Shandong Province, China
Jie Yang, Department of Pediatrics, Shandong University Qilu Hospital, Jinan 250012, Shandong Province, China
Author contributions: Xu YF, Ge FJ and Han B contributed to this work equally; Xu YF and Yang J designed research; Ge FJ and Yang XQ performed immunohistochemistry; Su H, Zhao AC, Zhao MH and Yang YB performed the in vitro experiments; Xu YF, Han B and Yang J analyzed the data and wrote the paper.
Supported by National Natural Science Foundation of China No. 81072110 and No. 81171951; grants from Independent Innovation Foundation of Shandong University, No. 2010TB012; Scientific Research Foundation for Returned Scholars, Ministry of Education of China.
Ethics approval: This study was performed with prior patient consents and the approval of the Institutional Clinical Ethics Review Board of Shandong University.
Conflict-of-interest: The authors declare no conflicting interest.
Data sharing: No additional unpublished data are available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:
Correspondence to: Jie Yang, MD, PhD, Department of Pediatrics, Shandong University Qilu Hospital, No. 107 Wenhuaxi Road, Jinan 250012, Shandong Province, China.
Telephone: +86-531-82169024 Fax: +86-531-82169024
Received: July 18, 2014
Peer-review started: July 20, 2014
First decision: August 15, 2014
Revised: September 2, 2014
Accepted: October 15, 2014
Article in press: October 15, 2014
Published online: March 21, 2015

AIM: To evaluate the prognostic value of high-mobility group box 1 (HMGB1) expression in intrahepatic cholangiocarcinoma (IHCC) and the possible underlying mechanism.

METHODS: Tissue microarray was constructed from 65 IHCC patients. Immunohistochemistry was performed to validate expression of HMGB1 and Vascular endothelial growth factor C (VEGF-C). Real-time PCR and Western blot analyses were used to study transcript and protein levels. The interaction between HMGB1 and VEGF-C was evaluated by siRNA, real-time PCR, and enzyme-linked immuno assays. The correlation between HMGB1 expression and other clinicopathologic parameters was analyzed by χ2 test, and the univariate as well as multivariate analyses were accomplished by Kaplan-Meier method and Cox-regression model, respectively.

RESULTS: Overall, overexpression of HMGB1 was found in 38/65 (58.8%) IHCCs, whereas VEGF-C overexpression was present in 30/65 (46.2%) cases. Overexpression of HMGB1 was significantly correlated with lymphatic microvessel density (P = 0.031, r = 0.268) and VEGF-C expression (P = 0.041, r = 0.254). With univariate analysis, both HMGB1 (P = 0.001) and VEGF-C (P = 0.004) were identified to be significantly associated with overall survival rate. Multivariate analysis indicated that HMGB1 could be served as an unfavorable independent prognostic factor in IHCCs (P = 0.005). siRNA knockdown of HMGB1 inhibited transforming growth factor-β-induced epithelial-mesenchymal transition (EMT) by elevating E-Cadherin expression and reducing expression of N-Cadherin, Vimentin and Snail in RBE cells. Further in vitro study revealed that HMGB1 silencing significantly decreased the level of VEGF-C, whereas the recombinant HMGB1 increased the VEGF-C level in RBE cells (both P < 0.05), which suggested that HMGB1 could promote lymphatic microvessel density, and subsequently lymphatic invasion, via promoting VEGF-C expression.

CONCLUSION: Our results define an important role of HMGB1 in the progression of cholangiocarcinoma, and HMGB1 may serve as a prognostic marker for IHCC patients.

Keywords: Epithelial-mesenchymal transition, High-mobility group box 1, Intrahepatic cholangiocarcinoma, Lymphatic microvessel density, Vascular endothelial growth factor C

Core tip: Cholangiocarcinoma is a lethal malignancy of the biliary tract, for which novel biomarkers are urgently needed for its management and treatment. This study shows that high-mobility group box 1 (HMGB1) is an independent prognostic factor in intrahepatic cholangiocarcinoma that positively correlates with lymphatic microvessel density and vascular endothelial growth factor C expression. Furthermore, HMGB1 enhances the secretion of vascular endothelial growth factor C and promotes epithelial-mesenchymal transition of RBE cells. Together, these results define an important role of HMGB1 in the progression of cholangiocarcinoma, which may serve as a prognostic marker for intrahepatic cholangiocarcinoma patients.