Tumors reprogram liver fat to weaken cancer-fighting T cells, in mice

Inside mice carrying tumors, the battle was being shaped far from the tumor itself. Researchers led by Yibin Kang and Yong Tang at Ludwig Princeton found that particles released by tumors can reprogram fat metabolism in the liver, weakening CD8+ T cells, the immune cells that attack cancer. The work was published in Cell Metabolism.

The mechanism begins with extracellular vesicles, tiny membrane-bound packages that tumors release into the bloodstream. They deliver molecular signals to immune cells living in the liver, prompting those cells to disrupt normal fat processing. A signaling cascade involving metadherin, a protein encoded by the MTDH gene, then contributes to fat accumulation in the liver and higher lipid levels in the blood. That lipid-rich environment reduces the fitness and cancer-killing ability of CD8+ T cells.

The researchers spent two years trying to establish why disrupting MTDH produced an immune effect. Bone marrow transplantation experiments showed that the benefit required MTDH to be disrupted in both liver cells and CD8+ T cells—not in just one of those cell populations. In preclinical models, coordinated MTDH loss reduced tumor growth and metastasis and made tumor-infiltrating T cells less prone to programmed cell death.

So what changes in practice? If the mechanism can eventually be translated to people, a treatment aimed at MTDH could work on two fronts at once: restoring the liver’s handling of fat while strengthening immune cells inside tumors. In mice, that combination also improved the effects of anti-PD-1 checkpoint blockade, an immunotherapy designed to stimulate the CD8+ T-cell response.

The limits are clear. The reported results come from mice and multiple cancer models, not from patients. The study also identifies MTDH as a potential target rather than an available medicine. Its appeal rests on earlier mouse findings that MTDH loss did not appear to cause harmful effects and protected against diet-induced obesity and fatty liver disease; whether that safety profile holds in humans remains untested.