Activation of the reverse transsulfuration pathway through NRF2/CBS confers erastin-induced ferroptosis resistance

Abstract Background Ferroptosis is an iron-dependent, lipid peroxide-mediated cell death that may be exploited to selective elimination of damaged and malignant cells. Recent studies have identified that small-molecule erastin specifically inhibits transmembrane cystine–glutamate antiporter system xc−, prevents extracellular cystine import and ultimately causes ferroptosis in certain cancer cells. In this study, we aimed to investigate the molecular mechanism underlying erastin-induced ferroptosis resistance in ovarian cancer cells. Methods We treated ovarian cancer cells with erastin and examined cell viability, cellular ROS and metabolites of the transsulfuration pathway. We also depleted cystathionine β-synthase (CBS) and NRF2 to investigate the CBS and NRF2 dependency in erastin-resistant cells. Results We found that prolonged erastin treatment induced ferroptosis resistance. Upon exposure to erastin, cells gradually adapted to cystine deprivation via sustained activation of the reverse transsulfuration pathway, allowing the cells to bypass erastin insult. CBS, the biosynthetic enzyme for cysteine, was constantly upregulated and was critical for the resistance. Knockdown of CBS by RNAi in erastin-resistant cells caused ferroptotic cell death, while CBS overexpression conferred ferroptosis resistance. We determined that the antioxidant transcriptional factor, NRF2 was constitutively activated in erastin-resistant cells and NRF2 transcriptionally upregulated CBS. Genetically repression of NRF2 enhanced ferroptosis susceptibility. Conclusions Based on these results, we concluded that constitutive activation of NRF2/CBS signalling confers erastin-induced ferroptosis resistance. This study demonstrates a new mechanism underlying ferroptosis resistance, and has implications for the therapeutic response to erastin-induced ferroptosis.

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Quinacrine-Induced Autophagy in Ovarian Cancer Triggers Cathepsin-L Mediated Lysosomal/Mitochondrial Membrane Permeabilization and Cell Death

Cancers ◽

10.3390/cancers13092004 ◽

2021 ◽

Vol 13 (9) ◽

pp. 2004

Author(s):

Prabhu Thirusangu ◽

Christopher L. Pathoulas ◽

Upasana Ray ◽

Yinan Xiao ◽

Julie Staub ◽

...

Keyword(s):

Ovarian Cancer ◽

Cell Death ◽

Cytochrome C ◽

Cancer Cells ◽

Apoptotic Cell ◽

Cathepsin L ◽

Membrane Permeabilization ◽

Apoptotic Cell Death ◽

Ovarian Cancer Cells ◽

Autophagic Flux

We previously reported that the antimalarial compound quinacrine (QC) induces autophagy in ovarian cancer cells. In the current study, we uncovered that QC significantly upregulates cathepsin L (CTSL) but not cathepsin B and D levels, implicating the specific role of CTSL in promoting QC-induced autophagic flux and apoptotic cell death in OC cells. Using a Magic Red® cathepsin L activity assay and LysoTracker red, we discerned that QC-induced CTSL activation promotes lysosomal membrane permeability (LMP) resulting in the release of active CTSL into the cytosol to promote apoptotic cell death. We found that QC-induced LMP and CTSL activation promotes Bid cleavage, mitochondrial outer membrane permeabilization (MOMP), and mitochondrial cytochrome-c release. Genetic (shRNA) and pharmacological (Z-FY(tBU)-DMK) inhibition of CTSL markedly reduces QC-induced autophagy, LMP, MOMP, apoptosis, and cell death; whereas induced overexpression of CTSL in ovarian cancer cell lines has an opposite effect. Using recombinant CTSL, we identified p62/SQSTM1 as a novel substrate of CTSL, suggesting that CTSL promotes QC-induced autophagic flux. CTSL activation is specific to QC-induced autophagy since no CTSL activation is seen in ATG5 knockout cells or with the anti-malarial autophagy-inhibiting drug chloroquine. Importantly, we showed that upregulation of CTSL in QC-treated HeyA8MDR xenografts corresponds with attenuation of p62, upregulation of LC3BII, cytochrome-c, tBid, cleaved PARP, and caspase3. Taken together, the data suggest that QC-induced autophagy and CTSL upregulation promote a positive feedback loop leading to excessive autophagic flux, LMP, and MOMP to promote QC-induced cell death in ovarian cancer cells.

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AMPK mediates curcumin-induced cell death in CaOV3 ovarian cancer cells

Oncology Reports ◽

10.3892/or_00000179 ◽

1994 ◽

Cited By ~ 4

Author(s):

Keyword(s):

Ovarian Cancer ◽

Cell Death ◽

Cancer Cells ◽

Ovarian Cancer Cells

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VCP inhibitors induce endoplasmic reticulum stress, cause cell cycle arrest, trigger caspase-mediated cell death and synergistically kill ovarian cancer cells in combination with Salubrinal

Molecular Oncology ◽

10.1016/j.molonc.2016.09.005 ◽

2016 ◽

Vol 10 (10) ◽

pp. 1559-1574 ◽

Cited By ~ 30

Author(s):

Prabhakar Bastola ◽

Lisa Neums ◽

Frank J. Schoenen ◽

Jeremy Chien

Keyword(s):

Cell Cycle ◽

Ovarian Cancer ◽

Endoplasmic Reticulum ◽

Cell Death ◽

Endoplasmic Reticulum Stress ◽

Cell Cycle Arrest ◽

Cancer Cells ◽

Ovarian Cancer Cells ◽

Induce Endoplasmic Reticulum Stress ◽

Cycle Arrest

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DEBIO 1143, an IAP inhibitor, reverses carboplatin resistance in ovarian cancer cells and triggers apoptotic or necroptotic cell death

Scientific Reports ◽

10.1038/s41598-018-35860-z ◽

2018 ◽

Vol 8 (1) ◽

Cited By ~ 17

Author(s):

Benoît Thibault ◽

Ludivine Genre ◽

Augustin Le Naour ◽

Clothilde Broca ◽

Eliane Mery ◽

...

Keyword(s):

Ovarian Cancer ◽

Cell Death ◽

Cancer Cells ◽

Ovarian Cancer Cells

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HOTTIP-miR-205-ZEB2 Axis Confers Cisplatin Resistance to Ovarian Cancer Cells

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2021.707424 ◽

2021 ◽

Vol 9 ◽

Author(s):

Yu-Jie Dong ◽

Wei Feng ◽

Yan Li

Keyword(s):

Ovarian Cancer ◽

Cancer Cells ◽

Cisplatin Resistance ◽

Clinical Problem ◽

Ovarian Cancer Cells ◽

Stem Cell Markers ◽

Gene Target ◽

Gynecological Malignancy ◽

Clonogenic Potential ◽

Resistant Cells

Ovarian cancer is a deadly gynecological malignancy with resistance to cisplatin a major clinical problem. We evaluated a role of long non-coding (lnc) RNA HOTTIP (HOXA transcript at the distal tip) in the cisplatin resistance of ovarian cancer cells, using paired cisplatin sensitive and resistant A2780 cells along with the SK-OV-3 cells. HOTTIP was significantly elevated in cisplatin resistant cells and its silencing reversed the cisplatin resistance of resistant cells. HOTTIP was found to sponge miR-205 and therefore HOTTIP silenced cells had higher levels of miR-205. Downregulation of miR-205 could attenuate HOTTIP-silencing effects whereas miR-205 upregulation in resistant cells was found to re-sensitize cells to cisplatin. HOTTIP silencing also led to reduced NF-κB activation, clonogenic potential and the reduced expression of stem cell markers SOX2, OCT4, and NANOG, an effect that could be attenuated by miR-205. Finally, ZEB2 was identified as the gene target of miR-205, thus completing the elucidation of HOTTIP-miR-205-ZEB2 as the novel axis which is functionally involved in the determination of cisplatin resistance in ovarian cancer cells.

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Isoflavones Isolated from the Seeds of Millettia ferruginea Induced Apoptotic Cell Death in Human Ovarian Cancer Cells

Molecules ◽

10.3390/molecules25010207 ◽

2020 ◽

Vol 25 (1) ◽

pp. 207 ◽

Cited By ~ 2

Author(s):

Yi-Yue Wang ◽

Jun Hyeok Kwak ◽

Kyung-Tae Lee ◽

Tsegaye Deyou ◽

Young Pyo Jang ◽

...

Keyword(s):

Ovarian Cancer ◽

Cell Death ◽

Cancer Cells ◽

Caspase 3 ◽

Apoptotic Cell ◽

Apoptotic Cell Death ◽

Ovarian Cancer Cells ◽

Human Ovarian Cancer ◽

Millettia Ferruginea ◽

Induced Apoptosis

The seeds of Millettia ferruginea are used in fishing, pesticides, and folk medicine in Ethiopia. Here, the anti-cancer effects of isoflavones isolated from M. ferruginea were evaluated in human ovarian cancer cells. We found that isoflavone ferrugone and 6,7-dimethoxy-3’,4’-methylenedioxy-8-(3,3-dimethylallyl)isoflavone (DMI) had potent cytotoxic effects on human ovarian cancer cell A2780 and SKOV3. Ferrugone and DMI treatment increased the sub-G1 cell population in a dose-dependent manner in A2780 cells. The cytotoxic activity of ferrugone and DMI was associated with the induction of apoptosis, as shown by an increase in annexin V-positive cells. Z-VAD-fmk, a broad-spectrum caspase inhibitor, and z-DEVD-fmk, a caspase-3 inhibitor, significantly reversed both the ferrugone and DMI-induced apoptosis, suggesting that cell death stimulated by the isoflavones is mediated by caspase-3-dependent apoptosis. Additionally, ferrugone-induced apoptosis was found to be caspase-8-dependent, while DMI-induced apoptosis was caspase-9-dependent. Notably, DMI, but not ferrugone, increased the intracellular levels of reactive oxygen species (ROS), and antioxidant N-acetyl-L-cysteine (NAC) attenuated the pro-apoptotic activity of DMI. These data suggest that DMI induced apoptotic cell death through the intrinsic pathway via ROS production, while ferrugone stimulated the extrinsic pathway in human ovarian cancer cells.

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