Basic Study
Copyright ©The Author(s) 2019. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Apr 28, 2019; 25(16): 1936-1949
Published online Apr 28, 2019. doi: 10.3748/wjg.v25.i16.1936
Signal transducer and activator of transcription 3 promotes the Warburg effect possibly by inducing pyruvate kinase M2 phosphorylation in liver precancerous lesions
Yang-Hui Bi, Wen-Qi Han, Ruo-Fei Li, Yun-Jiao Wang, Zun-Shu Du, Xue-Jiang Wang, Ying Jiang
Yang-Hui Bi, Wen-Qi Han, Ruo-Fei Li, Yun-Jiao Wang, Zun-Shu Du, Xue-Jiang Wang, Ying Jiang, Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing 100069, China
Author contributions: Bi YH and Han WQ contributed equally to this work; Jiang Y and Wang XJ designed the research; Jiang Y, Bi YH, Han WQ, Li RF, Wang XJ, and Du ZS performed the research; Jiang Y contributed new reagents or analytic tools; Jiang Y, Bi YH, and Han WQ analyzed the data and wrote the paper; all of the authors have read and approved the final manuscript.
Supported by the National Natural Science Foundation of China, No. 81070319; the Beijing Natural Science Foundation of China, No. 7102013; and the Beijing Municipal Education Commission Research Program, China, No. KM201610025004.
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 Capital Medical University [IACUC protocol number: (AEEI-2016-118)].
Conflict-of-interest statement: The authors have no conflicts of interest to declare.
Data sharing statement: The manuscript has no additional data 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/
Corresponding author: Ying Jiang, PhD, Professor, Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, No. 10, Xitoutiao, You An Men Wai, Beijing 100069, China. jiangy@ccmu.edu.cn
Telephone: +86-10-83911687
Received: January 27, 2019
Peer-review started: January 27, 2019
First decision: February 26, 2019
Revised: March 7, 2019
Accepted: March 24, 2019
Article in press: March 25, 2019
Published online: April 28, 2019
Abstract
BACKGROUND

Study shows that signal transducer and activator of transcription 3 (STAT3) can increase the Warburg effect by stimulating hexokinase 2 in breast cancer and upregulate lactate dehydrogenase A and pyruvate dehydrogenase kinase 1 in myeloma. STAT3 and pyruvate kinase M2 (PKM2) can also be activated and enhance the Warburg effect in hepatocellular carcinoma. Precancerous lesions are critical to human and rodent hepatocarcinogenesis. However, the underlying molecular mechanism for the development of liver precancerous lesions remains unknown. We hypothesized that STAT3 promotes the Warburg effect possibly by upregulating p-PKM2 in liver precancerous lesions in rats.

AIM

To investigate the mechanism of the Warburg effect in liver precancerous lesions in rats.

METHODS

A model of liver precancerous lesions was established by a modified Solt-Farber method. The liver pathological changes were observed by HE staining and immunohistochemistry. The transformation of WB-F344 cells induced with N-methyl-N’-nitro-N-nitrosoguanidine and hydrogen peroxide was evaluated by the soft agar assay and aneuploidy. The levels of glucose and lactate in the tissue and culture medium were detected with a spectrophotometer. The protein levels of glutathione S-transferase-π, proliferating cell nuclear antigen (PCNA), STAT3, and PKM2 were examined by Western blot and immunofluorescence.

RESULTS

We found that the Warburg effect was increased in liver precancerous lesions in rats. PKM2 and p-STAT3 were upregulated in activated oval cells in liver precancerous lesions in rats. The Warburg effect, p-PKM2, and p-STAT3 expression were also increased in transformed WB-F344 cells. STAT3 activation promoted the clonal formation rate, aneuploidy, alpha-fetoprotein expression, PCNA expression, G1/S phase transition, the Warburg effect, PKM2 phosphorylation, and nuclear translocation in transformed WB-F344 cells. Moreover, the Warburg effect was inhibited by stattic, a specific inhibitor of STAT3, and further reduced in transformed WB-F344 cells after the intervention for PKM2.

CONCLUSION

The Warburg effect is initiated in liver precancerous lesions in rats. STAT3 activation promotes the Warburg effect by enhancing the phosphorylation of PKM2 in transformed WB-F344 cells.

Keywords: Warburg effect, Hepatic progenitor cell, Signal transducer and activator of transcription 3, Pyruvate kinase M2, Liver precancerous lesion

Core tip: Signal transducer and activator of transcription 3 (STAT3) is stimulated in hepatocellular carcinoma and regulates the Warburg effect in many tumors. However, whether the activation of STAT3 can enhance the Warburg effect is unclear in liver precancerous lesions. Here, we provide the evidence that the Warburg effect was enhanced in liver precancerous lesions in rats, perhaps through up-regulating the expression of pyruvate kinase M2 (PKM2) and p-STAT3 in activated oval cells. STAT3 activation promotes the Warburg effect by activing PKM2 in transformed WB-F344 cells induced with N-methyl-N’-nitro-N-nitrosoguanidine and hydrogen peroxide.