Mitochondrial event as an ultimate step in ferroptosis

Abstract

In ferroptosis, the roles of mitochondria have been controversial. To explore the role of mitochondrial events in ferroptosis, we employed mitochondrial DNA-depleted ρ0 cells that are resistant to cell death due to enhanced expression of antioxidant enzymes. Expression of mitochondrial-type GPx4 (mGPx4) but no other forms of GPx4 was increased in SK-Hep1 ρ0 cells. Likely due to high mGPx4 expression, SK-Hep1 ρ0 cells were resistant to ferroptosis by erastin inhibiting xCT channel. In contrast, SK-Hep1 ρ0 cells were susceptible to cell death by a high concentration of RSL3 imposing ferroptosis by GPx4 inhibition. Accumulation of cellular ROS and oxidized lipids was observed in erastin- or RSL3-treated SK-Hep1 ρ+ cells but not in erastin-treated SK-Hep1 ρ0 cells. Mitochondrial ROS and mitochondrial peroxidized lipids accumulated in SK-Hep1 ρ+ cells not only by RSL3 but also by erastin acting on xCT on the plasma membrane. Mitochondrial ROS quenching inhibited SK-Hep1 ρ+ cell death by erastin or a high dose of RSL3, suggesting a critical role of mitochondrial ROS in ferroptosis. Ferroptosis by erastin or RSL3 was inhibited by a more than 20-fold lower concentration of MitoQ, a mitochondrial ROS quencher, compared to DecylQ, a non-targeting counterpart. Ferroptosis of SK-Hep1 ρ+ cells by erastin or RSL3 was markedly inhibited by a VDAC inhibitor, accompanied by significantly reduced accumulation of mitochondria ROS, total peroxidized lipids, and mitochondrial peroxidized lipids, strongly supporting the role of mitochondrial events in ferroptotic death and that of VDAC in mitochondrial steps of ferroptosis induced by erastin or RSL3. SK-Hep1 ρ+ cell ferroptosis by sorafenib was also suppressed by mitochondrial ROS quenchers, accompanied by abrogation of sorafenib-induced mitochondrial ROS and mitochondrial peroxidized lipid accumulation. These results suggest that SK-Hep1 ρ0 cells are resistant to ferroptosis due to upregulation of mGPx4 expression and mitochondrial events could be the ultimate step in determining final cell fate.

mTOR Inhibition Suppresses Salinomycin-Induced Ferroptosis in Breast Cancer Stem Cells by Ironing Out Mitochondrial Dysfunctions

“…Overall, these data indicate that mTOR inhibition affects various molecular regulators related to iron homeostasis. Metabolomic and proteomic analyses highlighted mitochondria as a key regulator of Sal-induced ferroptosis supporting the numerous studies showing that mitochondria are a major hub of ferroptosis [30][31][32] . Interestingly, Smethurst DG.…”

Mitochondrial Lipid Peroxidation Is Responsible for Ferroptosis

“…The fluorophore is conjugated with the penetrating triphenylphosphonium cation using a linker containing two peptide bonds. A similar probe with a different linker structure was described earlier under the name MitoPerOX [25] and was recently used to demonstrate mitochondrial lipid peroxidation in ferroptosis [7]. The specific oxidation of MitoCLox by lipid radicals, its selective accumulation in mitochondria of various cells, and the response to mitochondrial lipid peroxidation induced by oxidative stress is shown [14].…”

“…In contrast to these results, earlier it was reported that erastin effectively induced ferroptosis in cells depleted of mitochondria as a result of mitophagy stimulation [5] (and that an ETC complex I inhibitor promotes lipid peroxidation and ferroptosis [6]). Very recently, mitochondrial DNA depletion by selection in the presence of ethidium bromide has been reported to prevent ferroptosis induced by both erastin and RSL3, presumably due to increased expression of mitochondrial GPx4 [7]. These conflicting results indicate a complex and not fully understood the role of mitochondria in ferroptosis.…”

“…In the same study, the mitochondria-targeted antioxidant MitoQ (ubiquinol conjugated with triphenylphosphonium cation) was shown to inhibit ferroptosis, but its non-targeted counterpart, idebenone, was even more effective. MitoQ and the nitroxide-based mitochondria-targeted antioxidant MitoTEMPO were recently reported to prevent mitochondrial lipid peroxidation and ferroptosis induced by both erastin and RSL3, while decylubiquinion was found to be ineffective [7]. MitoTEMPO has also been reported to prevent doxorubicin-induced cardiac ferroptosis in mice [9].…”

Mechanism of ferroptosis in traditional chinese medicine for clinical treatment: A review

“…Erastin acts on system Xc-, inhibiting the system’s uptake of cystine, resulting in the reduction of endogenous GSH synthesis and the accumulation of intracellular ROS, thereby inducing ferroptosis ( Li et al, 2022b ). Further, RSL3, which targets GPX4, binds directly to GPX4 and inactivates it, leading to accumulation of lipid peroxides and induction of ferroptosis ( Oh et al, 2022 ). Ferrostatin-1 inhibits erastin-induced accumulation of ROS, thereby inhibiting ferroptosis ( Shao et al, 2022 ).…”