GOT1 inhibition promotes pancreatic cancer cell death by ferroptosis

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.

Ferroptosis: At the Crossroad of Gemcitabine Resistance and Tumorigenesis in Pancreatic Cancer

“…Moreover, researchers found that it promotes ferroptosis in human pancreatic cancer cell lines by increasing MFN1/2-dependent mitochondrial fusion [99]. At the same time, the study showed that ferroptosis could be triggered by inhibiting cystine import, GSH synthesis, or GPX4 in synergy with GOT1(cytosolic aspartate aminotransaminase) [100]. These verify the significance of ferroptosis in pancreatic cancer.…”

The Role of Iron in Cancer Progression

“…Moreover, as cell density-dependent E-cadherin and Merlin/Neurofibromin (NF2) loss can induce ferroptosis, Bao et al found that NF2-inactivated meningioma cells were sensitive to Erastin-induced ferroptosis by analyzing 35 meningioma samples (10 NF2 loss and 25 NF2 wildtype), and further confirmed that myoenhancer factor 2C (MEF2C) acted as a promoter of NF2 and CDH1, thereby inhibiting ferroptosisrelated lipid peroxidation and meningioma cell death (131). Notably, Kremer et al indicated that aspartate aminotransferase (GOT1) could damage mitochondrial oxidative phosphorylation and promote catabolism, resulting in the increase of unstable iron pool and susceptibility to ferroptosis, this effect suggests that inhibiting GOT1 could destroy the redox balance and proliferation in pancreatic ductal carcinoma, and establishes a biochemical link between GOT1 and ferroptosis (132). Few studies reported the direct crosstalk between ferroptosis and antitumor immunity, until Wang et al reported that CD8 + T cells induce ferroptosis in tumor cells, which is the direct evidence of the connection between ferroptosis and antitumor immunity (133).…”

“…Notably, Kremer et al. indicated that aspartate aminotransferase (GOT1) could damage mitochondrial oxidative phosphorylation and promote catabolism, resulting in the increase of unstable iron pool and susceptibility to ferroptosis, this effect suggests that inhibiting GOT1 could destroy the redox balance and proliferation in pancreatic ductal carcinoma, and establishes a biochemical link between GOT1 and ferroptosis ( 132 ). Few studies reported the direct crosstalk between ferroptosis and antitumor immunity, until Wang et al.…”

Ferroptosis-mediated Crosstalk in the Tumor Microenvironment Implicated in Cancer Progression and Therapy

“…In recent years, an increasing number of researchers have investigated the role of ferroptosis in the treatment, initiation, and progression of pancreatic cancer. Daniel et al found that cytosolic aspartate aminotransaminase (GOT1) inhibition represses mitochondrial metabolism and enhances labile iron availability through autophagy, which accelerates pancreatic cancer cell death by ferroptosis ( Kremer et al, 2021 ). Furthermore, specific and conditional depletion of pancreatic Slc7a11 could induce pancreatic tumor ferroptosis and inhibit pancreatic tumorigenesis in mice ( Badgley et al, 2020 ).…”

“…In extracellular environment, cysteine is often found in its oxidized form, cystine, and the cystine transported into cells through the system Xc − will be immediately reduced into cysteine to synthesize GSH. Recently, it has been reported that the limiting of exogenous cystine can promote the ferroptosis of pancreatic cancer cells by enhancing the transaminase enzyme GOT1 inhibition ( Kremer et al, 2021 ). The canonical function of GOT1 is to regulate the malate-aspartate shuttle to generate reduced NADPH, which is used to maintain redox balance and proliferation in PDAC.…”