Selective Mitochondrial Respiratory Complex I Subunit Deficiency Causes Tumor Immunogenicity

Targeting of specific metabolic pathways in tumor cells has the potential to sensitize them to immune-mediated attack. Here we provide evidence for a specific means of mitochondrial respiratory Complex I (CI) inhibition that improves tumor immunogenicity and sensitivity to immune checkpoint blockade (ICB). Targeted genetic deletion of the CI subunits Ndufs4 and Ndufs6, but not other subunits, induces an immune-dependent tumor growth attenuation in mouse melanoma models. We show that deletion of Ndufs4 induces expression of the transcription factor Nlrc5 and genes in the MHC class-I antigen presentation and processing pathway. This induction of MHC-related genes is driven by an accumulation of pyruvate dehydrogenase-dependent mitochondrial acetyl-CoA downstream of CI subunit deletion. This work provides a novel functional modality by which selective CI inhibition restricts tumor growth, suggesting that specific targeting of Ndufs4, or related CI subunits, increases T-cell mediated immunity and sensitivity to ICB. Overall design: To investeigate the transcriptional changes that lead to the observed immunogenicity of the sgNdufs4 cells, we performed gene expression profiling using data obtained from RNA-seq of the sgControl and sgNdufs4 cell lines under standard culture conditions.