Mechano-metabolic feedback connects tissue fluidity to mitochondrial DNA-dependent immunity in breast cancer

Why some tumors respond to immunotherapy ("hot" tumors) while others remain resistant ("cold" tumors) is a central challenge in oncology. Elevated RAB5A-dependent endocytosis drives tissue fluidization during the transition to invasive breast carcinoma, but its immunological consequences are unclear. Here we show that RAB5A-driven fluidization induces a mechano-metabolic stress response that disrupts the AMPK-AKAP1-DRP1 mitochondrial fission pathway, causing mitochondrial elongation. RAB5A vesicles interact with hyperfused mitochondria and promote BAX/BAK-dependent pore formation, leading to limited mitochondrial outer membrane permeabilization. This sub-lethal event is amplified by palmitoylated GASDERMIN A oligomerization on mitochondria, establishing a positive feedback loop. The resulting release of mitochondrial DNA activates the cGAS-STING innate immune pathway and drives a hyperinflammatory state. Consequently, RAB5A-expressing tumors in immunocompetent mice grow more slowly, show increased immune infiltration, and display enhanced sensitivity to immune-checkpoint blockade in a BAX/BAK-, cGAS/STING-, and mtDNA-dependent manner. These findings connect mechanical stress, mitochondrial dynamics, and innate immunity, revealing strategies to potentiate antitumor immunotherapy.