Mitochondrial complex I promotes kidney cancer metastasis

Most kidney cancers display metabolic dysfunction but how this relates to cancer progression in humans is unknown. We infused 13C-labeled nutrients during surgical tumour resection in over 80 patients with kidney cancer. Labeling from [U-13C]glucose varies across subtypes, indicating that the kidney environment alone cannot account for all metabolic reprogramming in these tumours. Compared to the adjacent kidney, clear cell renal cell carcinomas (ccRCC) display suppressed labelling of tricarboxylic acid (TCA) cycle intermediates in vivo and in organotypic cultures ex vivo, indicating that suppressed labeling is tissue intrinsic. Infusions of [1,2-13C]acetate and [U-13C]glutamine in patients, coupled with measurements of respiration in mitochondria isolated from kidneys and tumours, reveal electron transport chain (ETC) defects in ccRCC. However, ccRCC metastases unexpectedly have enhanced TCA cycle labeling compared to primary ccRCCs, indicating a divergent metabolic program during metastasis in patients. In mice, stimulating respiration or NADH recycling in kidney cancer cells is sufficient to promote metastasis, while inhibiting ETC complex I decreases metastasis. These findings indicate that metabolic properties and liabilities evolve during kidney cancer progression in humans, and that mitochondrial function is limiting for metastasis but not for growth at the original site.