Suppression of oxidative stress and improvement of liver functions in mice by ursolic acid via LKB1-AMP-activated protein kinase signaling
Authors: Ming Meng
Zhanxue Zhao
Haisong Zhang
Xianjiang Kang
Yongbin Yang
Yuanjun Liu
Journal: Journal of Gastroenterology and Hepatology (2015)
Discipline: CLINICAL MEDICINE
Keywords: AMPK; fibrosis; inflammation; liver; oxidative stress
Affiliations: College of Life Sciences, Hebei University, Baoding, China; Health Science Center, Hebei University, Baoding, China., Health Science Center; Hebei University; Baoding China, Department of Nephrology; Affiliated Hospital of Hebei University; Baoding China, College of Life Sciences; Hebei University; Baoding China, Department of Pharmacy; Bethune Medical Sergeant Academy; Shijiazhuang China

Abstract:  Background and aim: Hepatic cirrhosis is the final stage of liver dysfunction, characterized by diffuse fibrosis, which is the main response to the liver injury. This study is to investigate the effects of ursolic acid (UA) on liver functions and fibrosis in bile duct ligation (BDL) mice and to determine the underlying mechanisms. Methods: Cultured hepatocytes were treated with lipopolysaccharide (LPS) in the presence or absence of UA. The reactive oxygen species (ROS) level, protein levels of IκBα, iNOS and Cox-2, and NF-κB activation were detected, respectively. C57/BL6 and AMP-activated protein kinase (AMPK)α2(-/-) mice were subjected to BDL for 14 days. UA was administered by gavage. The markers of liver function and oxidative stress, and liver histopathology were analyzed after treatment. Results: Treatment of hepatocytes with UA dose-dependently activates AMPK, which is abolished by silence of liver kinase B1 (LKB1). LPS significantly increased ROS productions, apoptosis, NF-κB activation, and expressions of iNOS and Cox-2 in cultured hepatocytes. All these effects were blocked by co-incubation with UA. Importantly, silence of LKB1, AMPK, or iNOS/Cox-2 by small interference RNA transfection reversed UA-induced effects in cultured cells. In an animal study, 14-day BDL induced liver fibrosis and liver injury, accompanied with increased oxidative stress and protein expressions of iNOS and Cox-2 in liver. Treatment of UA significantly attenuated the BDL-induced detrimental effects in wild-type mice but not in AMPKα2(-/-) mice. Conclusion: UA via LKB1-AMPK signaling offers protective effects on BDL-induced liver injury in mice, which may be related to inhibition of oxidative stress. 

Retracted: No

PubPeer comments:
 The Editors of PLoS evidently contacted the present journal in 2017 to advise them of overlaps between a PLoS paper ([Zhao et al 2014] ) and the present paper. They also contacted the editors of *Asian Pacific Journal of Cancer Prevention* (on account of overlaps with [Fan et al 2015] ), who included that advice within their own Retraction Note: ------------------------------------------------------------------- u201cDear Editors of *Gastroenterology and Hepatology*, *Acta Pharmacologica Sinica*, *Asian Pac J Cancer Prev*, *Clinical and Experimental Hypertension*, I write to you from the editorial office of PLOS ONE to inform you of concerns related to duplicated content in articles published by your journals. We have been following up on concerns of overlapping text and duplicate Western blots within the following PLOS ONE article: [1] Berberine Improves Kidney Function in Diabetic Mice via AMPK Activation https: doi.org 10.1371 journal.pone.0113398 Received: June 9, 2014; Accepted: October 23, 2014; Published: November 19, 2014 It was initially brought to our attention that there is duplication of Western blot images between the PLOS ONE article and the following published papers: - [2] Brain Injury (Received 28 Oct 2013, Accepted 4 Jan 2015, Published online 20 Mar 2015) doi: 10.3109 02699052.2015.1004746: Figure 6b GAPDH is similar to Figure 2A AMPK in [1] - [3] Exp Mol Pathol (Received 24 Feb 2014, Accepted 10 Sep 2014, Available online 16 Sep 2014) doi:10.1016 j.yexmp.2014.09.006: Figure 5B GAPDH is similar to Figure 2A AMPK in [1]; Figure 5C Occludin is similar to Figure 2A LKB1 in [1] - [4] Korean J Physiol Pharmacol, (Received 7 Nov 2013, Accepted 3 Jan 2016) doi: 10.4196 kjpp.2016.20.4.325 RETRACTED: Figure 6B GAPDH is similar to Figure 2A AMPK [1] Please note that the KJPP paper has been retracted as a result of the content duplication issues. During the course of our follow up, we have discovered additional instances of possible duplication as follows: - [5] Gastroenterology and Hepatology (Accepted 6 Aug 2014, Accepted ms online 28 Aug 2014, Published 23 Feb 2015) doi:10.1111 jgh.12723: Figure 1d AMPK is similar to Figure 2A AMPK in [1], Figure 3a iNOS is similar to Figure 2A LKB1 in [1] - [6] Acta Pharmacologica Sinica (Received 4 Mar 2014, Accepted 28 July 2014, Published 17 Nov 2014) doi: 10.1038 aps.2014.88: Figure 1 A and B bar charts are similar to Figure 1 A and B bar charts in [1], Figure 1E AMPK is similar to Figure 2A AMPK in [1], Figure 1E p-AMPK is similar to Figure 2A P-AMPK in [1], Figure 1E bar chart is similar to the Figure 2A bar chart in [1] - [7] Asian Pac J Cancer Prev (Published Jan 2014) doi: 10.7314 APJCP.2014.15.2.677: Figure 3A GAPDH is similar to Figure 2A AMPK in [1] and p27 kip1 is similar to Figure 2A P-AMPK in [1] - [8] Clinical and Experimental Hypertension (Received 15 Sep 2015, Accepted 24 Nov 2015, Published 5 May 2016) doi: 10.3109 10641963.2015.1131288: Figure 2A LKB1 and P-AMPK are similar to Figure 2A LKB1 and P-AMPK in [1], Figure 2B P-AMPK and AMPK are similar to Figure 2B P-AMPK and AMPK in [1], Figure 2A and B bar charts appear similar in both articles. Figures 1A, B and C including Western blots and charts appear similar in both articles. Figure 6C AMPK is similar to Figure 2A AMPK in [1] (note that authors Min Hu and Bo Liu may be the same as authors on the retracted KJPP paper above) Articles [5], [6], [7], and [8] contain various amounts of duplicated text in the Results sections when compared to the PLOS ONE article. Note that there may be other instances of duplicated data and or text between the above articles aside from those affecting the PLOS ONE article. For at least some of the duplicated text, it appears that some of the manuscripts were under consideration at overlapping times. We have been informed that an external biotechnology company conducted the Western blot experiments and provided the raw blots to the authors for the PLOS ONE paper. How the duplications in text and figures arose remains unresolved. Although our correspondence with the authors about this matter is ongoing, we have determined that it is appropriate to issue a retraction of the PLOS ONE article, and the retraction notice will provide details of the similarities in content with the above-listed articles. We will also report this matter to the PLOS ONE authorsu2019 institution. I hope that the information provided above is helpful. If you have any questions in the course of any follow up on this matter, please do not hesitate to get in touch. Best wishes ----------------------------------------------- Naturally I wonder whether the editors of *Journal of Gastroenterology and Hepatology* have investigated the advice from PLoS. [2] [has been retracted] , on account of the overlap with [3]. [6] [has been retracted] , on account of the overlap with [7]. , 
 This paper is part of a set (18 papers identified so far, published between 2014-2017) that appear to be connected to each other by the use of the same Western blots and some other figure panels. Many of these panels appeared first in papers by Shuangxi Wang, Ping Song, and Ming-Hui Zou, published around 2007-2012. These papers are otherwise seemingly unrelated, with different sets of authors and institutions. The panels do not represent the same proteins or experiments. An initial subset of 8 papers was identified in the retraction of Long Zhao et al., PLOS ONE (2014), DOl: 10.1371 journal.pone.0113398 - https: pubpeer.com publications 29F5C2BCC1C389A566BB106F3F825C. There, the authors admitted to have used an external company for the preparation of the Western blots. Therefore, I will call this the [External Company Paper Mill.] In addition to the re-use of images from older papers by Shuangxi Wang, Ping Song, and Ming-Hui Zou, most papers from the External Company paper set include more-than-expected papers by this trio in the References, sometimes constituting 10% of all references or more. This might suggest that this paper mill might have been set up for citation boosting. In this paper, I counted 11 of the 43 references to be from Shuangxi Wang, Ping Song, and or Ming-Hui Zou. ![file] ,