Hepatic Deletion of Janus Kinase 2 Counteracts Inflammation, Oxidative Stress and Liver Cancer Formation in Growth Hormone Transgenic Mice

ABSTRACT: Impairment of hepatic growth hormone (GH)- janus kinase (JAK) 2- signal transducer and activator of transcription (STAT) 5 signaling is associated with non-alcoholic fatty liver disease, while persistently high levels of GH can result in hepatic inflammation and liver cancer. Despite its anti-steatotic functions, STAT5 in hepatocytes has been implicated to be a tumor suppressor, whose loss strongly accelerates tumor formation in the presence of high GH levels. Yet, it remains unclear whether the upstream kinase JAK2 exerts similar tumor-suppressive functions. To address this question, we crossed a mouse model of inflammatory liver cancer (GHtg) to mice harboring the hepatocyte-specific deletion of JAK2 (JAK2Δhep) and compared them to GHtgSTAT5Δhep mice. We show that JAK2 deficiency in the GHtg background resulted in profound steatosis at young age due to ectopic lipid redistribution and increased hepatic de novo lipogenesis. Generation of reactive oxygen species (ROS) was increased in all genotypes compared to wildtype controls, while DNA damage and lipid peroxidation were observed only in GHtg and GHtgSTAT5Δhep animals. Importantly, Affymetrix analysis revealed that the expression of glutathione S-transferases (GSTs), a major group of detoxification enzymes, was strongly upregulated in JAK2 deficient livers. In vitro and in vivo studies further confirmed that ruxolitinib-mediated inhibition of JAK2 led to significant upregulation of GSTs, indicating a direct involvement of JAK2 in the negative regulation of these genes. Strikingly, despite equally profound hepatosteatosis and ROS production as in GHtgSTAT5Δhep mice, loss of JAK2 significantly delayed tumor formation in GHtg mice. Conclusion: Thus, in absence of hepatic JAK2, mice were protected against elevated ROS-induced DNA damage and lipid peroxidation through significant expression of GSTs.

ORGANISM(S): Mus musculus

SUBMITTER: Madeleine Themanns 

PROVIDER: E-MTAB-3774 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress