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J Biol Chem. 2017 Mar 3;292(9):3789-3799. doi: 10.1074/jbc.M116.752519. Epub 2017 Jan 18.

Janus Kinase 2 (JAK2) Dissociates Hepatosteatosis from Hepatocellular Carcinoma in Mice.

Author information

1
From the Toronto General Hospital Research Institute, Toronto, Ontario M5G 2C4, Canada.
2
the Institute of Medical Science, University of Toronto, Toronto, Ontario M5S 1A8, Canada.
3
the Institute of Medical Research, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul 03181, Korea.
4
the Department of Nutritional Sciences, University of Toronto, Toronto, Ontario M5S 3E2, Canada.
5
the Eppley Institute for Research in Cancer and Allied Diseases and the Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska 68198-6805, and.
6
From the Toronto General Hospital Research Institute, Toronto, Ontario M5G 2C4, Canada, mwoo@uhnresearch.ca.
7
the Division of Endocrinology, Department of Medicine, Toronto General Hospital, University Health Network, University of Toronto, Toronto, Ontario M5G 1L7, Canada.

Abstract

Hepatocellular carcinoma is an end-stage complication of non-alcoholic fatty liver disease (NAFLD). Inflammation plays a critical role in the progression of non-alcoholic fatty liver disease and the development of hepatocellular carcinoma. However, whether steatosis per se promotes liver cancer, and the molecular mechanisms that control the progression in this disease spectrum remain largely elusive. The Janus kinase signal transducers and activators of transcription (JAK-STAT) pathway mediates signal transduction by numerous cytokines that regulate inflammation and may contribute to hepatocarcinogenesis. Mice with hepatocyte-specific deletion of JAK2 (L-JAK2 KO) develop extensive fatty liver spontaneously. We show here that this simple steatosis was insufficient to drive carcinogenesis. In fact, L-JAK2 KO mice were markedly protected from chemically induced tumor formation. Using the methionine choline-deficient dietary model to induce steatohepatitis, we found that steatohepatitis development was completely arrested in L-JAK2 KO mice despite the presence of steatosis, suggesting that JAK2 is the critical factor required for inflammatory progression in the liver. In line with this, L-JAK2 KO mice exhibited attenuated inflammation after chemical carcinogen challenge. This was associated with increased hepatocyte apoptosis without elevated compensatory proliferation, thus thwarting expansion of transformed hepatocytes. Taken together, our findings identify an indispensable role of JAK2 in hepatocarcinogenesis through regulating critical inflammatory pathways. Targeting the JAK-STAT pathway may provide a novel therapeutic option for the treatment of hepatocellular carcinoma.

KEYWORDS:

Janus kinase (JAK); cell death; cell proliferation; diethylnitrosamine; hepatocellular carcinoma; inflammation; mouse; non-alcoholic fatty liver disease

PMID:
28100771
PMCID:
PMC5339761
DOI:
10.1074/jbc.M116.752519
[Indexed for MEDLINE]
Free PMC Article

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