RSL3 and Erastin differentially regulate redox signaling to promote Smac mimetic-induced cell death

Abstract

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 α-tocopherol (α-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.

MicroRNA‐214‐3p enhances erastin‐induced ferroptosis by targeting ATF4 in hepatoma cells

“…These findings indicate that hepatoma cells are susceptible to ferroptosis inducer. Erastin inhibits the cysteine‐dependent GSH synthesis, thereby facilitating the accumulation of toxic ROS and lipid oxidation products, MDA (Dachert et al, 2016; Yang & Stockwell, 2016). We observed that erastin promoted lipid oxidation in hepatoma cells by determining the alterations in these lipid oxidation‐associated molecules.…”

“…Small compounds, such as erastin, Ras‐selective lethal small molecule 3 (RSL3), RSL5, and some drugs, such as sorafenib and artesunate (Xie et al, 2016) have been identified as ferroptosis inducers due to their ability to induce iron‐dependent accumulation of lipid reactive oxygen species (ROS; Dixon et al, 2012). These ferroptosis inducers exert antitumor activities in many types of malignancies (Dachert, Schoeneberger, Rohde, & Fulda, 2016; Sato et al, 2018; Shintoku et al, 2017), including HCC (Nie, Lin, Zhou, Wu, & Zheng, 2018; Sun et al, 2016). Although inducing ferroptosis is a promising anticancer strategy, the negative regulators of ferroptosis which inhibit cellular iron uptake and/or limit ROS production may hinder the application of ferroptosis inducers in anticancer therapy (Shen et al, 2018; Xie et al, 2016).…”

“…Small compounds, such as erastin, Ras-selective lethal small molecule 3 (RSL3), RSL5, and some drugs, such as sorafenib and artesunate (Xie et al, 2016) have been identified as ferroptosis inducers due to their ability to induce iron-dependent accumulation of lipid reactive oxygen species (ROS; Dixon et al, 2012). These ferroptosis inducers exert antitumor activities in many types of malignancies (Dachert, Schoeneberger, Rohde, & Fulda, 2016;Sato et al, 2018;Shintoku et al, 2017), including HCC (Nie, Lin, Zhou, Wu, & Zheng, 2018;Sun et al, 2016).…”

Ferroptosis is associated with oxygen-glucose deprivation/reoxygenation-induced Sertoli cell death

“…Previous studies have provided evidence that ferroptosis serves a major role in I/R-induced tissue and cell damage, and that targeting ferroptotic pathways may improve protection against I/R injury (4)(5)(6)(7)(8)(9)21). Ferroptosis is a non-apoptotic form of regulated cell death triggered by inactivation of the lipid repair enzyme GPX4 and subsequent lipid peroxidation (4,37,39,40). Lipid peroxidation has routinely been described as a key factor that may lead to spermatogenesis disturbance by damaging Sertoli cells in testicular I/R injury (16,56).…”

“…via reducing lipid ROS. GPX4 has been described as the major regulator of erastin-induced cancer cell ferroptosis and OGd/R-induced ferroptotic renal tubular epithelial cell death (24,37,(39)(40)(41). A previous study demonstrated that GPX4 is a prerequisite for sperm development (42).…”