GOT1 inhibition promotes pancreatic cancer cell death by ferroptosis

Daniel M Kremer,Andrew C Little,Mengrou Shan,Christopher J Halbrook,Zeribe C Nwosu,Milan R Savani,Michael A Badgley,Barbara Scott Nelson ,Marina Pasca Di Magliano,Nneka E Mbah,John M Asara,Ting Gao ,Samuel K Mcbrayer,Peter Sajjakulnukit,Emily L Yarosz ,Li Zhang,Stephanie Wisner,Galloway Thurston,Eileen S Carpenter,Johanna Ramos,Carmine F Palermo,Samuel A Kerk,Howard C Crawford,Lin Lin,Yatrik M Shah,Kenneth P Olive,Anthony Andren ,Nicholas Cusmano,Nupur K Das,Sean W Hou,Amy L Myers ,Brian Magnuson,Stephen A Sastra,Costas A Lyssiotis

doi:10.1038/s41467-021-24859-2

Abstract

Cancer metabolism is rewired to support cell survival in response to intrinsic and environmental stressors. Identification of strategies to target these adaptions is an area of active research. We previously described a cytosolic aspartate aminotransaminase (GOT1)-driven pathway in pancreatic cancer used to maintain redox balance. Here, we sought to identify metabolic dependencies following GOT1 inhibition to exploit this feature of pancreatic cancer and to provide additional insight into regulation of redox metabolism. Using pharmacological methods, we identify cysteine, glutathione, and lipid antioxidant function as metabolic vulnerabilities following GOT1 withdrawal. We demonstrate that targeting any of these pathways triggers ferroptosis, an oxidative, iron-dependent form of cell death, in GOT1 knockdown cells. Mechanistically, we reveal that GOT1 inhibition represses mitochondrial metabolism and promotes a catabolic state. Consequently, we find that this enhances labile iron availability through autophagy, which potentiates the activity of ferroptotic stimuli. Overall, our study identifies a biochemical connection between GOT1, iron regulation, and ferroptosis.

Highlights

Cancer metabolism is rewired to support cell survival in response to intrinsic and environmental stressors
OAA is reduced to malate by cytosolic Malate Dehydrogenase 1 (MDH1) and is oxidized by Malic Enzyme 1 (ME1) to generate nicotinamide adenine dinucleotide phosphate (NADPH), which is utilized to support redox balance and proliferation in PDA3
We found human pancreatic stellate cells, human lung fibroblasts (IMR-90), and human non-transformed pancreatic exocrine cells were minimally affected upon GOT1 knockdown, in agreement with previous results, suggesting that this pathway may be dispensable in non-transformed cells (Supplementary Fig. 1h–i)[3,8], highlighting a potential therapeutic window

Summary

Introduction

Cancer metabolism is rewired to support cell survival in response to intrinsic and environmental stressors. We demonstrate that targeting any of these pathways triggers ferroptosis, an oxidative, iron-dependent form of cell death, in GOT1 knockdown cells. Our previous work demonstrated that PDA rewire the malate-aspartate shuttle to generate reduced nicotinamide adenine dinucleotide phosphate (NADPH), a major currency for biosynthesis and redox balance (Fig. 1a)[3]. The activity of this non-canonical pathway was orchestrated by mutant KRAS through control of the expression of the cytosolic aspartate aminotransaminase (GOT1). GOT1 knockdown in combination with inhibitors of cystine import or lipid antioxidant machinery led to ferroptosis: an oxidative, non-apoptotic, and iron-dependent form of cell death[4,5]. The cells increased labile iron pools which increased their susceptibility to ferroptosis

Methods

Results

Conclusion