Hepatocyte-derived calcineurin regulates the development of hepatocellular carcinoma independent of hepatic steatohepatitis

Hepatocellular carcinoma (HCC) is caused by chronic damage to the liver originating from viral infections, alcohol abuse or metabolic diseases. Non-alcoholic fatty liver disease (NAFLD) is characterized by hepatic lipid accumulation. A subset of patients further develops hepatic inflammation resulting in non-alcoholic steatohepatitis (NASH), which can in a subset of patients lead to the development of HCC. Within NASH and HCC, the role of common inflammatory signaling pathways such as those of the nuclear factor of kappa-B and STAT3 have been extensively investigated. Here we aimed to investigate the roles of calcineurin (Cn) and its downstream mediators of the nuclear factor of activated T-cell family (NFAT) in NASH-associated HCC. To study the role of Cn, we used male mice with hepatocyte-specific deletion of calcineurin (AlbCretg/wtCnb1fl/fl) which we treated with diethylnitrosamine (DEN) at 2 weeks of age and fed a high-fat diet deficient for choline (CD-HFD) for 32 weeks. These mice showed a reduction in tumor size and tumor load compared to wildtype (WT) mice (Cre-negative Cnb1fl/fl littermates), which underwent the same treatment. Additionally, hepatic tumors from WT litters presented with an increase in tumor necrosis factor-alpha and Il1beta mRNA expression compared to AlbCretg/wtCnb1fl/fl mice. Neither a short-term treatment with CD-HFD plus DEN nor a long-term treatment with CD-HFD without DEN showed differences in hepatic or systemic inflammation between AlbCretg/wtCnb1fl/fl-mice and WT littermates, suggesting that hepatocyte-derived calcineurin does not control HCC development through regulation of hepatic inflammation. Inhibiting the binding of Cn to NFATs by intravenous application of VIVIT, a peptide known to disrupt Cn-NFAT-associations, also resulted in decreased tumor multiplicity and size. In summary, these data indicate that the Cn-NFAT axis has a pro-oncogenic role in HCC without affecting the severity of NASH. Further research will focus on the mechanisms of how hepatic calcineurin regulates HCC development and its potential use in the prevention and treatment of HCC.