Erastin

Erastin is a cell-permeable ferroptosis activatior and an antitumor agent that is selective for cell expressing oncogene RAS.

Ferroptosis is a unique iron-dependent form of nonapoptotic cell death. It is triggered by oncogenic RAS-selective lethal small molecule erastin. Acitvation of ferroptosis lead to nonapoptotic destruction of cancer cells.

In BJ-TERT/LT/ST/RASV12 cells, Erastin activated a rapid, oxidative and non-apoptotic cell death process. It exerted lethality in human cancer cells with HRAS, KRAs or BRAF oncogenic mutation involving the RAS-RAF-MEF pathway and acted via modulating VDAC (volatage-dependent anion channels). [1] In HT 1080 cells, Erastin-induced death triggered the cytosolic ROS accumulation and the induced oxidative death was iron dependent. Erastin also inhibited the activity of independent cystine/glutamate antiporter, system xc−. [2]

References:
[1] Yagoda N, von Rechenberg M, Zaganjor E, Bauer AJ, Yang WS, Fridman DJ, Wolpaw AJ, Smukste I, Peltier JM, Boniface JJ, Smith R, Lessnick SL, Sahasrabudhe S, Stockwell BR.  RAS-RAF-MEK-dependent oxidative cell death involving voltage-dependent anion channels.  Nature. 2007 Jun 14;447(7146):864-8.
[2] Dixon SJ, Lemberg KM, Lamprecht MR, Skouta R, Zaitsev EM, Gleason CE, Patel DN, Bauer AJ, Cantley AM, Yang WS, Morrison B 3rd, Stockwell BR.  Ferroptosis: an iron-dependent form of nonapoptotic cell death.  Cell. 2012 May 25;149(5):1060-72.

Conjugation to the sigma-2 ligand SV119 overcomes uptake blockade and converts dm-Erastin into a potent pancreatic cancer therapeutic.[Pubmed:27244881]

Oncotarget. 2016 Jun 7;7(23):33529-41.

Cancer-selective drug delivery is an important concept in improving treatment while minimizing off-site toxicities, and sigma-2 receptors, which are overexpressed in solid tumors, represent attractive pharmacologic targets. Select sigma-2 ligands have been shown to be rapidly internalized selectively into cancer cells while retaining the capacity to deliver small molecules as drug cargoes. We utilized the sigma-2-based drug delivery concept to convert Erastin, a clinically underperforming drug, into a potent pancreatic cancer therapeutic. The Erastin derivative des-methyl Erastin (dm-Erastin) was chemically linked to sigma-2 ligand SV119 to create SW V-49. Conjugation increased the killing capacity of dm-Erastin by nearly 35-fold in vitro and reduced the size of established tumors and doubled the median survival in syngeneic and patient-derived xenograft models when compared to non-targeted dm-Erastin. Mechanistic analyses demonstrated that cell death was associated with robust reactive oxygen species production and could be efficiently antagonized with antioxidants. Mass spectrometry was employed to demonstrate selective uptake into pancreatic cancer cells. Thus, targeted delivery of dm-Erastin via conjugation to the sigma-2 ligand SV119 produced efficient tumor control and prolonged animal survival with minimal off-target toxicities, and SW V-49 represents a promising new therapeutic with the potential to advance the fight against pancreatic cancer.

RSL3 and Erastin differentially regulate redox signaling to promote Smac mimetic-induced cell death.[Pubmed:27588473]

Oncotarget. 2016 Sep 27;7(39):63779-63792.

Redox mechanisms play an important role in the control of various signaling pathways. Here, we report that Second mitochondrial activator of caspases (Smac) mimetic-induced cell death is regulated by redox signaling. We show that RSL3, a glutathione (GSH) peroxidase (GPX) 4 inhibitor, or Erastin, an inhibitor of the cystine/glutamate antiporter, cooperate with the Smac mimetic BV6 to induce reactive oxygen species (ROS)-dependent cell death in acute lymphoblastic leukemia (ALL) cells. Addition of the caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (zVAD.fmk) fails to rescue ROS-induced cell death, demonstrating that RSL3/BV6- or Erastin/BV6-induced cell death occurs in a caspase-independent manner. Interestingly, the iron chelator Deferoxamine (DFO) significantly inhibits RSL3/BV6-induced cell death, whereas it is unable to rescue cell death by Erastin/BV6, showing that RSL3/BV6-, but not Erastin/BV6-mediated cell death depends on iron. ROS production is required for both RSL3/BV6- and Erastin/BV6-induced cell death, since the ROS scavenger alpha-tocopherol (alpha-Toc) rescues RSL3/BV6- and Erastin/BV6-induced cell death. By comparison, genetic or pharmacological inhibition of lipid peroxidation by GPX4 overexpression or ferrostatin (Fer)-1 significantly decreases RSL3/BV6-, but not Erastin/BV6-induced cell death, despite inhibition of lipid peroxidation upon exposure to RSL3/BV6 or Erastin/BV6. Of note, inhibition of lipid peroxidation by Fer-1 protects from RSL3/BV6-, but not from Erastin/BV6-stimulated ROS production, indicating that other forms of ROS besides lipophilic ROS occur during Erastin/BV6-induced cell death. Taken together, RSL3/BV6 and Erastin/BV6 differentially regulate redox signaling and cell death in ALL cells. While RSL3/BV6 cotreatment induces ferroptotic cell death, Erastin/BV6 stimulates oxidative cell death independently of iron. These findings have important implications for the therapeutic targeting of redox signaling to enhance Smac mimetic-induced cell death in ALL.

The Protective Role of Mitochondrial Ferritin on Erastin-Induced Ferroptosis.[Pubmed:28066232]

Front Aging Neurosci. 2016 Dec 20;8:308.

Ferroptosis, a newly identified form of regulated cell death, is characterized by overwhelming iron-dependent accumulation of lethal lipid reactive oxygen species (ROS). Preventing cellular iron overload by reducing iron uptake and increasing iron storage may contribute to inhibit ferroptosis. Mitochondrial ferritin (FtMt) is an iron-storage protein that is located in the mitochondria, which has a significant role in modulating cellular iron metabolism. Recent studies showed that FtMt played inhibitory effects on oxidative stress-dependent neuronal cell damage. However, the potential role of FtMt in the progress of ferroptosis in neuronal cells has not been studied. To explore this, we established ferroptosis models of cell and drosophila by Erastin treatment. We found that overexpression of FtMt in neuroblastoma SH-SY5Y cells significantly inhibited Erastin-induced ferroptosis, which very likely was achieved by regulation of iron homeostasis. Upon Erastin treatment, significant increases of cellular labile iron pool (LIP) and cytosolic ROS were observed in wild-type SH-SY5Y cells, but not in the FtMt-overexpressed cells. Consistent with that, the alterations of iron-related proteins in FtMt-overexpressed cells were different from that of the control cells. We further investigated the role of FtMt in Erastin-induced ferroptosis in transgenic drosophila. We found that the wild-type drosophilas fed an Erastin-containing diet didn't survive more than 3 weeks. In contrast, the FtMt overexpressing drosophilas fed the same diet were survival very well. These results indicated that FtMt played a protective role in Erastin-induced ferroptosis.

The ferroptosis inducer erastin enhances sensitivity of acute myeloid leukemia cells to chemotherapeutic agents.[Pubmed:27308510]

Mol Cell Oncol. 2015 May 26;2(4):e1054549.

Acute myeloid leukemia (AML) is the most common type of leukemia in adults. Development of resistance to chemotherapeutic agents is a major hurdle in the effective treatment of patients with AML. The quinazolinone derivative Erastin was originally identified in a screen for small molecules that exhibit synthetic lethality with expression of the RAS oncogene. This lethality was subsequently shown to occur by induction of a novel form of cell death termed ferroptosis. In this study we demonstrate that Erastin enhances the sensitivity of AML cells to chemotherapeutic agents in an RAS-independent manner. Erastin dose-dependently induced mixed types of cell death associated with ferroptosis, apoptosis, necroptosis, and autophagy in HL-60 cells (AML, NRAS_Q61L), but not Jurkat (acute T-cell leukemia, RAS wild type), THP-1 (AML, NRAS_G12D), K562 (chronic myelogenous leukemia, RAS wild type), or NB-4 (acute promyelocytic leukemia M3, KRAS_A18D) cells. Treatment with ferrostatin-1 (a potent ferroptosis inhibitor) or necrostatin-1 (a potent necroptosis inhibitor), but not with Z-VAD-FMK (a general caspase inhibitor) or chloroquine (a potent autophagy inhibitor), prevented Erastin-induced growth inhibition in HL-60 cells. Moreover, inhibition of c-JUN N-terminal kinase and p38, but not of extracellular signal-regulated kinase activation, induced resistance to Erastin in HL-60 cells. Importantly, low-dose Erastin significantly enhanced the anticancer activity of 2 first-line chemotherapeutic drugs (cytarabine/ara-C and doxorubicin/adriamycin) in HL-60 cells. Collectively, the induction of ferroptosis and necroptosis contributed to Erastin-induced growth inhibition and overcame drug resistance in AML cells.

Ferroptosis: an iron-dependent form of nonapoptotic cell death.[Pubmed:22632970]

Cell. 2012 May 25;149(5):1060-72.

Nonapoptotic forms of cell death may facilitate the selective elimination of some tumor cells or be activated in specific pathological states. The oncogenic RAS-selective lethal small molecule Erastin triggers a unique iron-dependent form of nonapoptotic cell death that we term ferroptosis. Ferroptosis is dependent upon intracellular iron, but not other metals, and is morphologically, biochemically, and genetically distinct from apoptosis, necrosis, and autophagy. We identify the small molecule ferrostatin-1 as a potent inhibitor of ferroptosis in cancer cells and glutamate-induced cell death in organotypic rat brain slices, suggesting similarities between these two processes. Indeed, Erastin, like glutamate, inhibits cystine uptake by the cystine/glutamate antiporter (system x(c)(-)), creating a void in the antioxidant defenses of the cell and ultimately leading to iron-dependent, oxidative death. Thus, activation of ferroptosis results in the nonapoptotic destruction of certain cancer cells, whereas inhibition of this process may protect organisms from neurodegeneration.

RAS-RAF-MEK-dependent oxidative cell death involving voltage-dependent anion channels.[Pubmed:17568748]

Nature. 2007 Jun 14;447(7146):864-8.

Therapeutics that discriminate between the genetic makeup of normal cells and tumour cells are valuable for treating and understanding cancer. Small molecules with oncogene-selective lethality may reveal novel functions of oncoproteins and enable the creation of more selective drugs. Here we describe the mechanism of action of the selective anti-tumour agent Erastin, involving the RAS-RAF-MEK signalling pathway functioning in cell proliferation, differentiation and survival. Erastin exhibits greater lethality in human tumour cells harbouring mutations in the oncogenes HRAS, KRAS or BRAF. Using affinity purification and mass spectrometry, we discovered that Erastin acts through mitochondrial voltage-dependent anion channels (VDACs)--a novel target for anti-cancer drugs. We show that Erastin treatment of cells harbouring oncogenic RAS causes the appearance of oxidative species and subsequent death through an oxidative, non-apoptotic mechanism. RNA-interference-mediated knockdown of VDAC2 or VDAC3 caused resistance to Erastin, implicating these two VDAC isoforms in the mechanism of action of Erastin. Moreover, using purified mitochondria expressing a single VDAC isoform, we found that Erastin alters the permeability of the outer mitochondrial membrane. Finally, using a radiolabelled analogue and a filter-binding assay, we show that Erastin binds directly to VDAC2. These results demonstrate that ligands to VDAC proteins can induce non-apoptotic cell death selectively in some tumour cells harbouring activating mutations in the RAS-RAF-MEK pathway.

Identification of genotype-selective antitumor agents using synthetic lethal chemical screening in engineered human tumor cells.[Pubmed:12676586]

Cancer Cell. 2003 Mar;3(3):285-96.

We used synthetic lethal high-throughput screening to interrogate 23,550 compounds for their ability to kill engineered tumorigenic cells but not their isogenic normal cell counterparts. We identified known and novel compounds with genotype-selective activity, including doxorubicin, daunorubicin, mitoxantrone, camptothecin, sangivamycin, echinomycin, bouvardin, NSC146109, and a novel compound that we named Erastin. These compounds have increased activity in the presence of hTERT, the SV40 large and small T oncoproteins, the human papillomavirus type 16 (HPV) E6 and E7 oncoproteins, and oncogenic HRAS. We found that overexpressing hTERT and either E7 or LT increased expression of topoisomerase 2alpha and that overexpressing RAS(V12) and ST both increased expression of topoisomerase 1 and sensitized cells to a nonapoptotic cell death process initiated by Erastin.