The role of autoproteolysis and mitoribosomal proteins in the regulation of the mitochondrial LACTB tumor suppressor.

Cancer cells inactivate the mitochondrial tumor suppressor LACTB through enhanced autoproteolysis mediated by MRPS34 in breast cancers.

• Why it matters: Understanding post-translational mechanisms of tumor suppressor inactivation is crucial, as they represent a less explored pathway compared to genetic or epigenetic changes, and could reveal new therapeutic targets.
• What they did: The study identified LACTB's autoproteolytic activity as a key regulatory process, showing that cancer cells increase MRPS34 levels to promote LACTB self-degradation, thereby reducing its tumor suppressor function.
• The result: This mechanism highlights how cancer cells manipulate mitochondrial proteins to evade tumor suppression, offering potential avenues for restoring LACTB activity and developing targeted therapies.