Establishment and Characterization of the Murine Liver Tumor Cell Line ΔCN60 with Conditional Caspase-8 and IKKγ/NEMO...

Caspase-8 and the NF-κB essential modulator (NEMO, also referred to as IKKγ) play critical roles in controlling TNF-α-induced cell death and survival in hepatocytes. The aim of this study was to generate a hepatocyte-derived cell line in which the Casp8 and Nemo genes can be conditionally inactivated simultaneously to investigate the significance of the corresponding signaling pathways. To this end, we induced hepatocellular carcinoma in Casp8^f/fNemo^f/f mice using diethylnitrosamine and established an immortalized hepatoma cell line from explanted liver tumors, which is subsequently referred to as ΔCN60. ΔCN60 cells still retain floxed Casp8 and Nemo alleles, allowing for efficient Cre-mediated deletion to generate Casp8^ΔNemo^Δ derivatives. Loss of both Caspase-8 and NEMO inhibits cell proliferation, increases the expression of tumor and progenitor markers (AFP, CD133), reduces albumin expression, and blocks TNF-α-induced NF-κB p65 nuclear translocation. ΔCN60 Casp8^ΔNemo^Δ cells display altered sensitivity to prolonged TNF-α exposure, suggesting a potential shift in necroptosis-associated signaling pathways, although necroptotic cell death was not directly demonstrated. ΔCN60 serves as a versatile hepatoma model for investigating Caspase-8/NEMO-dependent TNF-α signaling and hepatocyte plasticity and may help prioritize future in vivo experiments by enabling selected mechanistic questions to be addressed first in vitro.