Metabolic requirement for GOT2 in pancreatic cancer depends on environmental context

SA Kerk, L Lin, AL Myers, DJ Sutton, A Andren… - Elife, 2022 - elifesciences.org
SA Kerk, L Lin, AL Myers, DJ Sutton, A Andren, P Sajjakulnukit, L Zhang, Y Zhang
Elife, 2022elifesciences.org
Mitochondrial glutamate-oxaloacetate transaminase 2 (GOT2) is part of the malateaspartate
shuttle, a mechanism by which cells transfer reducing equivalents from the cytosol to the
mitochondria. GOT2 is a key component of mutant KRAS (KRAS*)-mediated rewiring of
glutamine metabolism in pancreatic ductal adenocarcinoma (PDA). Here, we demonstrate
that the loss of GOT2 disturbs redox homeostasis and halts proliferation of PDA cells in vitro.
GOT2 knockdown (KD) in PDA cell lines in vitro induced NADH accumulation, decreased …
Abstract
Mitochondrial glutamate-oxaloacetate transaminase 2 (GOT2) is part of the malateaspartate shuttle, a mechanism by which cells transfer reducing equivalents from the cytosol to the mitochondria. GOT2 is a key component of mutant KRAS (KRAS*)-mediated rewiring of glutamine metabolism in pancreatic ductal adenocarcinoma (PDA). Here, we demonstrate that the loss of GOT2 disturbs redox homeostasis and halts proliferation of PDA cells in vitro. GOT2 knockdown (KD) in PDA cell lines in vitro induced NADH accumulation, decreased Asp and α-ketoglutarate (αKG) production, stalled glycolysis, disrupted the TCA cycle, and impaired proliferation. Oxidizing NADH through chemical or genetic means resolved the redox imbalance induced by GOT2 KD, permitting sustained proliferation. Despite a strong in vitro inhibitory phenotype, loss of GOT2 had no effect on tumor growth in xenograft PDA or autochthonous mouse models. We show that cancer-associated fibroblasts (CAFs), a major component of the pancreatic tumor microenvironment (TME), release the redox active metabolite pyruvate, and culturing GOT2 KD cells in CAF conditioned media (CM) rescued proliferation in vitro. Furthermore, blocking pyruvate import or pyruvate-to-lactate reduction prevented rescue of GOT2 KD in vitro by exogenous pyruvate or CAF CM. However, these interventions failed to sensitize xenografts to GOT2 KD in vivo, demonstrating
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