MAVS/CMTM6 axis couples mitochondrial homeostasis to immunogenic senescence via CCL3-driven T-cell recruitment in renal carcinoma.

[BACKGROUND] Mitochondrial antiviral signaling protein (MAVS), a central adaptor in cytosolic RNA sensing, is critical for antitumor innate immunity and maintains mitochondrial homeostasis via its mitochondrial localization. Mitochondrial dysfunction acts as a key driver and amplifier of the senescence-associated secretory phenotype (SASP), a double-edged sword in tumor progression. However, whether tumor-intrinsic MAVS can regulate antitumor immunity via cellular senescence independently of its well-established interferon signaling remains unclear.

[METHODS] Our study employed an integrated strategy. Clinically, we profiled MAVS expression and its association with prognosis and immune infiltration in renal tumor specimens. Mechanistic insights into tumor-intrinsic MAVS were gained through a battery of techniques spanning quantitative PCR, immunoblotting, RNA sequencing, senescence and mitochondrial function assays, confocal imaging, immunohistochemical, mass spectrometry, and co-immunoprecipitation. In vivo, we used MAVS-deficient models combined with CD8 T-cell depletion, programmed cell death protein-1 (PD-1) blockade, or reactive oxygen species (ROS) scavenging by N-acetylcysteine (NAC), with immune infiltration characterized by flow cytometry.

[RESULTS] Clinical evidence links elevated MAVS expression in renal tumors to poor prognosis and diminished CD8 T-cell infiltration. Strikingly, tumor-intrinsic MAVS deficiency curbed malignant progression by triggering cellular senescence and fostering a permissive niche for CD8 T-cell activation and recruitment. Mechanistically, MAVS orchestrates mitochondrial integrity by co-localizing with and stabilizing chemokine-like factor-like MARVEL transmembrane domain-containing 6 (CMTM6), thereby shielding it from lysosomal degradation. Disruption of this axis provoked mitochondrial dysfunction and ROS accumulation, culminating in senescence and an SASP marked by chemokine C-C motif ligand 3 (CCL3). Thus, despite dampening canonical innate immune signaling, MAVS deletion unleashed potent antitumor immunity via CCL3-mediated CD8 T-cell recruitment, an effect abolished by CD8 T-cell depletion or ROS scavenging with NAC. Leveraging this paradigm, we demonstrated that tumor-specific MAVS deficiency acts synergistically with PD-1 blockade to achieve robust therapeutic efficacy.

[CONCLUSIONS] Our findings establish the tumor-intrinsic MAVS/CMTM6/CCL3 axis as a previously unrecognized critical regulator of senescence-driven antitumor immunity in renal carcinoma. Therapeutic targeting of this axis presents a promising strategy to curtail tumor progression and potentiate immunotherapy.