Endocytic mechano-metabolic feedback linking tissue fluidity to mitochondrial DNA–dependent immunity in breast cancer

Why some tumors are "hot" and respond to immunotherapy while others remain "cold" is a central challenge in oncology. Here, we identify a mechanical process that, while driving malignant invasion, paradoxically converts immunologically "cold" tumors "hot." Previous evidence indicates that the transition from in situ to invasive breast carcinoma is driven by tissue fluidization mediated by pathologically elevated RAB5A-dependent endocytosis. This fluidization generates mechanical stress leading to a robust cGASdependent transcriptional rewiring. Here, we investigated its mechanistic and immunological consequences. We find that the pathological RAB5A elevation defines an immune-active transcriptional program that predicts improved survival in triple-negative and HER2-positive breast cancers. We further show that RAB5A-driven fluidization elicits a mechano-metabolic response characterized by profound mitochondrial elongation through dysregulation of the AMPK–AKAP1–DRP1 fission pathway. Mechanical and metabolic stress, together with RAB5A-vesicle interactions on hyperfused mitochondria, compromise mitochondrial integrity by triggering a RAB5ABAX/BAK-mediated pore formation. This event enhances GASDERMIN A expression, which becomes palmitoylated and oligomerizes on mitochondria, establishing a positive feedback loop that amplifies minority mitochondrial outer-membrane permeabilization (miMOMP). This sub-lethal miMOMP causes mitochondrial damage and the release of mitochondrial DNA (mtDNA), which potently activates the cGAS/STING innate immune axis, explaining the observed hyper inflammatory state.Consequently, RAB5A-expressing tumors in immunocompetent mice exhibit slow growth, enhanced immune infiltration, and heightened sensitivity to immune-checkpoint blockade in a BAX/BAK-, cGAS/STING- and mtDNA-dependent fashion. These findings reveal a novel interplay between mechanical stress, mitochondrial dynamics and integrity, and immune activation, presenting new therapeutic opportunities to boost antitumor immunity in cancer therapy.