MLKL in liver parenchymal cells promotes liver cancer in murine metabolic dysfunction-associated steatotic liver disease

Abstract The rising prevalence of hepatocellular carcinoma (HCC) in the last decade is mostly attributable to the growing epidemic of metabolic dysfunction-associated steatotic liver diseases (MASLD). However, the transition from steatosis to steatohepatitis (MASH) and ultimately to HCC is not fully understood. As an executioner protein of necroptosis, the mixed-lineage kinase domain-like protein (MLKL) has been proposed to contribute to MASH and HCC development. To investigate its role in disease progression, mice whose liver parenchymal cells (LPCs) no longer expressed MLKL ( Mlkl LPC-KO ) were compared to their control counterparts ( Mlkl fl/fl ) using an experimental model combining diabetes induction and a high-fat high-sugar diet (HFHSD) for 4, 8, or 12 weeks. Notably, HFHSD failed to induce detectable hepatic necroptosis in Mlkl fl/fl mice, with no phosphorylated MLKL observed by Western blot. Both genotypes displayed similar steatosis and mild fibrosis, consistent with comparable MASH severity, and this condition progressed to HCC. Interestingly, the incidence of liver tumors in Mlkl LPC-KO mice was significantly reduced, which was associated with a delay in the onset of systemic and hepatic inflammation. At the early stage of the disease (4th week), the absence of MLKL in LPCs appeared to confer a protective effect on the liver, reducing metabolic stress, as reflected by a lower ceramide-to- sphingomyelin ratio, along with oxidative stress and DNA damage. Altogether, our data suggest that MLKL in LPCs contributes to HCC initiation in the context of MASH, potentially involving its described non-canonical role within mitochondria, promoting oxidative stress, a cancer hallmark. This study provides new insights into evaluating the therapeutic potential of targeting MLKL, as its inhibition in LPCs may represent an effective strategy for treating MASH-related HCC.