Abstract 275: Lack of electron acceptors contributes to redox stress and growth arrest in asparagine-starved sarcoma cells

Abstract

Background. Amino acids are integral components of cancer metabolism. Adequate availability of the non-essential amino acid asparagine is necessary to support growth and survival of various cancer cell types, including sarcoma cells. Methods. Different mass spectrometry approaches were employed to determine changes in the metabolome of asparagine-deprived mouse and human sarcoma cells, which may be responsible for arrested growth and apoptosis due to asparagine depletion. Results. Lower aspartate levels, higher aspartate/glutamine ratios and lower levels of tricarboxylic acid (TCA) cycle metabolites in asparagine-deprived sarcoma cells indicated a redirection of TCA cycle flux and were accompanied by reduced NAD+/NADH ratios, consistent with relative deficiency of electron acceptors in asparagine-starved cells. Elevated lactate/pyruvate ratios may be due to compensatory regeneration of NAD+ through increased pyruvate to lactate conversion by lactate dehydrogenase in asparagine-deprived cells. Supplementation with exogenous pyruvate, which was previously shown to serve as electron acceptor in cells challenged by reductive stress, restored aspartate levels, NAD+/NADH ratios, lactate/pyruvate ratios and cell growth in asparagine-deprived cells. Treatment with chemicals disrupting regeneration of NAD+ in the electron transport chain (e.g. metformin) further enhanced the anti-proliferative and pro-apoptotic effects of asparagine depletion. Conclusions. We conclude that asparagine deprivation, through metabolic reprogramming, causes reductive stress, which, in turn, results in lower aspartate levels in asparagine-starved cells. These changes are major contributors to the growth arrest observed in asparagine-starved cells. Future studies are needed to further elucidate the cellular processes that contribute to lack of electron acceptors in asparagine-starved tumor cells. Citation Format: Christoph Bauer, Meret Quante, Carla Regina, Michaela Schneider, Geoffroy Andrieux, Oliver Gorka, Olaf Groß, Melanie Boerries, Bernd Kammerer, Simone Hettmer. Lack of electron acceptors contributes to redox stress and growth arrest in asparagine-starved sarcoma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 275.