Scientists discovered that a cancer‑related protein called MTDH gets a fatty‑acid tag (S‑palmitoylation) in breast cancer cells, which changes how the cells handle fats and makes them more resistant to a type of cell death called ferroptosis. Removing this tag changes the protein’s interactions and could make the cancer cells more vulnerable.

S-palmitoylation is a dynamic and reversible post-translational modification that plays crucial roles in cancer progression. Here, we found the oncogene of metadherin (MTDH) modulates lipid metabolism and ferroptosis by its S-palmitoylation. We demonstrate that MTDH is S-palmitoylated at Cys-75 in the endoplasmic reticulum by ZDHHC1/9 and S-depalmitoylated by APT1. The flexible loop and the α-helix length in the MTDH N-terminus affect its S-palmitoylation level. In addition, metabolomics analysis found that the S-palmitoylated MTDH increases intracellular levels of triglycerides, phosphatidylethanolamines, and phosphatidylcholines. However, the non-S-palmitoylation form of MTDH-CS enhanced the interaction of between MTDH and the ferroptosis enhancer of Acyl-CoA synthetase long-chain family member 4 (ACSL4), thereby reducing ferroptosis sensitivity in breast cancer cell. Taken together, targeting MTDH S-palmitoylation may represent a novel strategy for breast cancer therapy.