The role of ATP synthase subunit e (ATP5I) in mediating the metabolic and antiproliferative effects of metformin in cancer cells

Here, we identify the subunit e of F₁F₀-ATP synthase (ATP5I) as a target of metformin, a first-in-class antidiabetic biguanide. ATP5I maintains the stability of F₁F₀-ATP synthase dimers, which is crucial for shaping cristae morphology. We demonstrate that ATP5I interacts with a biguanide analogue in vitro, and disabling its expression by CRISPR–Cas9 in pancreatic cancer cells leads to the same phenotype as biguanide-treated cells, including mitochondrial morphology alterations, reduction of the NAD + /NADH ratio, inhibition of oxidative phosphorylation (OXPHOS), rescue of respiration by uncouplers, and a compensatory increase in glycolysis. Notably, metformin disrupts F₁F₀-ATP synthase oligomerization, leading to the accumulation of vestigial assembly intermediates in pancreatic and osteosarcoma cancer cells, a phenotype also observed upon ATP5I inactivation in pancreatic cancer cells. Moreover, ATP5I knockout (KO) cells exhibit resistance to the antiproliferative effects of biguanides