Abstract 1541: Possible role of ectopic ATP synthase mediating metabolic hypoxic adaptation in retinoblastoma

Abstract Altered metabolism is a hallmark of cancer. Yet how metabolic reprogramming benefits tumor growth remains unclear. In retinoblastoma (RB), we have shown that estrogen-related receptor gamma (ESRRG) undergoes continuous positive selection during tumor evolution as evidenced by an ongoing accumulation of genomic aberrations that increase ESRRG activity. Transcriptional analysis revealed that ESRRG is pivotal in mediating metabolic reprogramming, with cells displaying preferential aerobic fermentation and microenvironment acidification. Here, we show that the combination of hypoxic stress and ESRRG deregulation leads to increased ectopic expression of mitochondrial ATP synthase on the plasma membrane, where it is critical to cancer cell proliferation. Translocation of ATP synthase to the plasma membrane was augmented in a time-dependent manner when RB cells were exposed to hypoxia. Pre-treatment of cells with an ESRRG inhibitor eliminated this ATP synthase translocation. Both the F0 proton channel and F1 catalytic domains were identified on the outer plasma membrane by confocal microscopy and flow cytometry. Intracellular ATP concentration, measured by luciferase reaction, was significantly increased by media acidification. Inhibition of lactate/proton export through monocarboxylate transporters resulted in media alkalinization and a significant decrease in intracellular ATP, which could be rescued by subsequent exogenous acidification of the media, suggesting that ectopic ATP synthase uses the proton motive force generated by extracellular acidification to synthesize ATP. A novel F0-targeting ATP synthase inhibitor resulted in near complete cell death of RB cells but showed minimal effect on non-malignant control cells. Interestingly, this drug did not impact the reductive capacity of cancer cell mitochondria compared to control cells, indicating that the drug preferentially affects plasma membrane ATP synthesis at these concentrations. These findings suggest that ATP synthase on the surface of RB cells plays an important role in metabolic adaptation and cell proliferation. These results demonstrate that the use of ATP synthase inhibitors targeting the F0 domain may represent an innovative new strategy to target cancer cells. Citation Format: Samantha A. McLaughlin, Zelia M. Correa, Stefan Kurtenbach, J. William Harbour, Daniel Pelaez. Possible role of ectopic ATP synthase mediating metabolic hypoxic adaptation in retinoblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1541.