Cytochrome P450 oxidoreductase contributes to phospholipid peroxidation in ferroptosis

Abstract

Ferroptosis is widely involved in degenerative diseases in various tissues including kidney, liver and brain, and is a targetable vulnerability in clear-cell carcinomas and therapy-resistant cancers. Accumulation of phospholipid hydroperoxides in cellular membranes is recognized as the hallmark and rate-limiting step of ferroptosis; however, the enzymes contributing to lipid peroxidation remain poorly characterized. Using genome-wide, CRISPR/Cas9-mediated suppressor screens, we identify cytochrome P450 oxidoreductase (POR) as a contributor to ferroptotic cell death in cancer cells exhibiting inherent and induced susceptibility to ferroptosis. By genetic depletion of POR in cancer cells, we reveal that POR contributes to ferroptosis across a wide range of lineages and cell-states, and in response to distinct mechanisms of ferroptosis induction. Using systematic lipidomic profiling, we further map POR's activity to the lipid peroxidation step in ferroptosis. Hence, our work suggests POR as a key mediator of ferroptosis and a potential druggable target for developing anti-ferroptosis therapeutics.

Modulation of ferroptosis sensitivity by TXNRD1 in pancreatic cancer cells

“…2 Such efforts have reliably uncovered core determinants of PUFA-phospholipid biology, including acyl-CoA synthetase long chain family member 4 (ACSL4) and lysophosphatidylcholine acyltransferase 3 (LPCAT3) as strong positive regulators of ferroptosis sensitivity. 9,21 In addition, these screens have highlighted the existence of lineage-specific modulators of ferroptosis sensitivity. The contribution of the hypoxia-inducible factor (HIF) pathway in ferroptosis sensitivity of clear-cell renal cell carcinoma and the role of cytochrome P450 oxidoreductase (POR) enzyme in ferroptosis sensitivity of melanoma serve as compelling examples of this phenomenon.…”

“…The contribution of the hypoxia-inducible factor (HIF) pathway in ferroptosis sensitivity of clear-cell renal cell carcinoma and the role of cytochrome P450 oxidoreductase (POR) enzyme in ferroptosis sensitivity of melanoma serve as compelling examples of this phenomenon. 9,21 In the context of pancreatic cancer, a CRISPR-Cas9 ferroptosis suppressor screen using ML210 ( Figure 1A) performed in KP-4, a pancreatic ductal adenocarcinoma (PDAC) cell line, identified several candidate lineagespecific regulators ( Table 1). The presence of TXNRD1 in this list attracted our attention because such a finding is at odds with general perspectives within the field on the link between the thioredoxin and ferroptosis pathways.…”

Oxidative Damage and Antioxidant Defense in Ferroptosis

“…In particular, POR binds its cofactors, such as flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). This complex mediated electron supplementation to cytochrome P450 from NADPH is required for erastin-, FIN56-, ML210-, or RSL3-induced lipid peroxidation and subsequent ferroptosis in melanoma and other cancer cells (Zou et al, 2020). Although the exact mechanism of POR-mediated lipid peroxidation is still unknown, POR may accelerate the cycling between ferrous and ferric iron in the heme component of cytochrome P450 (Zou et al, 2020).…”

“…This complex mediated electron supplementation to cytochrome P450 from NADPH is required for erastin-, FIN56-, ML210-, or RSL3-induced lipid peroxidation and subsequent ferroptosis in melanoma and other cancer cells (Zou et al, 2020). Although the exact mechanism of POR-mediated lipid peroxidation is still unknown, POR may accelerate the cycling between ferrous and ferric iron in the heme component of cytochrome P450 (Zou et al, 2020). Given that the conditional knockout of POR in the liver leads to a decrease in the metabolism and lipid accumulation in mice (Henderson et al, 2003), the pathological role of POR-mediated ferroptosis in tissue damage and metabolism disease is worthy of further study.…”

Integrative pharmacogenomic profiling identifies novel cancer drugs and gene networks modulating ferroptosis sensitivity in pan-cancer

“…Ferroptosis suppressor protein 1 (FSP1), also known as apoptosis-inducing factor mitochondria associated 2 (AIFM2), was proposed to play a GPX4-independent anti-ferroptosis role in cancer [5,6], and combined inhibition of GPX4 and FSP1 synergistically enhances ferroptosis [5,6]. Recent studies have also identi ed additional factors with a potential role in regulating ferroptosis [7][8][9][10]. Despite the progress, the molecular mechanisms underlying the complexity of the ferroptosis process remain poorly understood.…”