Liver Protein MLKL Linked to Obesity-Related Tumor Growth

New Role Identified for Cell Death Protein

A protein previously known for causing cell death appears to drive liver cancer progression linked to high-fat diets. Researchers at the University of Oklahoma published findings in the journal Hepatology showing that mixed lineage kinase domain-like protein (MLKL) promotes liver tumors by disrupting cellular energy production.

The study examined mice fed a high-fat diet designed to mimic Western eating patterns. In these animals, levels of MLKL rose significantly in liver cells, but the protein did not trigger cell death as expected. Instead, elevated MLKL reduced mitochondrial performance, which allowed tumors to form and expand.

Mitochondrial Disruption Drives Tumor Expansion

The mechanism identified in the study centers on the interaction between MLKL and mitofusin 2 (MFN2), a protein required to maintain normal mitochondria. When MLKL levels increased following a high-fat diet, levels of MFN2 dropped, which impaired the ability of mitochondria to produce energy.

Removing MLKL from mouse liver cells reversed this cascade. With MLKL absent, MFN2 levels returned to normal, mitochondrial function improved, and the mice developed fewer and smaller liver tumors.

Tumor Reduction Occurred Without Clearing Liver Fat

Removing MLKL reduced liver tumor formation without resolving underlying liver injury or fat accumulation. The mice still had fatty liver, inflammation, and fibrosis despite showing smaller and fewer tumors.

This outcome shows that MLKL promotes tumor formation through a separate metabolic pathway rather than the standard progression from inflammation to scarring. Direct interventions targeting this pathway could provide a way to address tumor growth even if underlying fatty liver remains present.

• MLKL deletion did not reduce liver fat accumulation or inflammation.
• Fibrosis levels remained unchanged in the absence of the protein.
• Tumor burden dropped despite the ongoing presence of liver injury.

Human Data and Early Study Limitations

The research team also analyzed human liver cancer data sets and patient tissue samples. Tumors expressing higher levels of MLKL correlated with lower overall survival rates in patients with hepatocellular carcinoma (HCC).

These findings remain preclinical because the therapeutic experiments took place in mice and cell cultures. While higher MLKL levels correlate with worse outcomes in human tumor tissue, clinical trials will be necessary to test whether experimental MLKL inhibitors are safe or effective in humans.

What This Means for Managing Liver Health

Nearly 30 percent of adults in the United States have fatty liver disease, which has become a primary driver of liver cancer alongside viral hepatitis and chronic alcohol intake. People diagnosed with liver cancer face an overall five-year survival rate of approximately 22 percent.

Patients managing fatty liver disease should discuss established monitoring schedules, metabolic blood panels, and lifestyle measures with their clinician. Investigational drugs targeting MLKL are still in laboratory development and are not available for clinical use.