Smac-mimetic enhances antitumor effect of standard chemotherapy in ovarian cancer models via Caspase 8-independent mechanism

AbstractOvarian cancer is the most lethal gynecological cancer in the US. Standard treatment consists of surgery followed by chemotherapies relying on apoptotic tumor cell death. Most women with advanced stage disease will relapse, suggesting that this disease is characterized by primary and acquired resistance to chemotherapy, and novel approaches to treatment are greatly needed. Low Caspase 8 expression levels in ovarian cancers correlate with resistance to apoptotic chemotherapy, and a subpopulation of patients with low Caspase 8 levels exhibit poorer overall survival after standard-of-care treatment. We hypothesized that low Caspase 8 function reduces the ability of cancer cells to undergo apoptosis when exposed to standard chemotherapy and that second mitochondria-derived activator of caspases (Smac)-mimetics could increase cell death in combination with chemotherapy. Here we show that combination treatment with a Smac-mimetic can target tumor cells with low Caspase 8 and induce necroptotic cell death. We investigated the in vitro effect of Smac-mimetic added to carboplatin and paclitaxel treatment of ovarian cancer cells expressing wild type and low Caspase 8 levels, which resulted in a 2–4-fold enhancement of cell death. Mice bearing subcutaneous or intraperitoneal ovarian xenografts showed greater aggressiveness of Caspase 8-deficient versus wild-type tumors; combined in vivo treatment with chemotherapy and Smac-mimetic resulted in >50% decrease in low Caspase 8 xenograft growth, as well as significantly enhanced overall survival, especially when given simultaneously with paclitaxel. Surprisingly, Smac-mimetic on the same day as carboplatin decreased mouse survival compared to when it was given on a sequential day of treatment. The antagonism was associated with a decrease in DNA damage markers, emphasizing the importance of optimizing timing of drug administration. Clinical validation of such approaches is needed to increase the effectiveness of current standard ovarian cancer treatment.

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Conjugation to a SMAC mimetic potentiates sigma-2 ligand induced tumor cell death in ovarian cancer

Molecular Cancer ◽

10.1186/1476-4598-13-50 ◽

2014 ◽

Vol 13 (1) ◽

pp. 50 ◽

Cited By ~ 16

Author(s):

Gunjal Garg ◽

Suwanna Vangveravong ◽

Chenbo Zeng ◽

Lynne Collins ◽

Mary Hornick ◽

...

Keyword(s):

Ovarian Cancer ◽

Cell Death ◽

Tumor Cell ◽

Tumor Cell Death ◽

Smac Mimetic

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The USP7 Inhibitor P5091 Induces Cell Death in Ovarian Cancers with Different P53 Status

Cellular Physiology and Biochemistry ◽

10.1159/000484062 ◽

2017 ◽

Vol 43 (5) ◽

pp. 1755-1766 ◽

Cited By ~ 18

Author(s):

Mengying Wang ◽

Yayun Zhang ◽

Taishu Wang ◽

Jinrui Zhang ◽

Zhu Zhou ◽

...

Keyword(s):

Cell Cycle ◽

Ovarian Cancer ◽

Cell Death ◽

Cancer Cells ◽

Pharmacological Intervention ◽

Ovarian Cancer Cells ◽

Mutant P53 ◽

Wild Type ◽

Ovarian Cancers ◽

Wild Type P53

Background/Aims: Ovarian cancer is often diagnosed at later stages with poor prognosis. Recent studies have associated the expression of deubiquitylase USP7 with the survival of ovarian cancers. Being a cysteine protease, USP7 could become a target for pharmacological intervention. Therefore, in this study, we assessed the influence of its inhibitor P5091 on ovarian cancer cells. Methods: Ovarian cancer cells were treated with P5091, and cell proliferation was measured with MTT assay; cell morphology was inspected under a phase-contrast microscope; cell cycle and cell death were examined by flow cytometry. To gain mechanistic insights into its effects, immunoblotting was performed to detect USP7, HDM2, p53, p21, apoptosis and autophagy related proteins. Results: P5091 effectively suppressed the growth of ovarian cancer cells, caused cell cycle blockage, and induced necrosis and apoptosis with more severe phenotypes observed in HeyA8 cells with wild-type p53 than in OVCAR-8 cells with mutant p53. P5091 also prompted autophagy, with more efficient p62 degradation in HeyA8. Conclusion: P5091 shows efficacy in suppressing ovarian cancers harbouring wild-type and mutant p53. Its effects seemed to be enhanced by wild-type p53. The potency of this USP7 inhibitor also correlated with autophagy to some extent. Therefore, the pharmacological targeting of USP7 may serve as a potential therapeutic strategy and warrants further investigation.

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Combination of targeted SMAC mimetic SW IV-134 and standard chemotherapy improves cell death and survival in ovarian cancer murine model

Gynecologic Oncology ◽

10.1016/j.ygyno.2017.03.204 ◽

2017 ◽

Vol 145 ◽

pp. 87

Author(s):

P.S. Binder ◽

Y.M. Hashim ◽

S. Vangveravong ◽

M.A. Powell ◽

D.G. Mutch ◽

...

Keyword(s):

Ovarian Cancer ◽

Cell Death ◽

Murine Model ◽

Standard Chemotherapy ◽

Smac Mimetic

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Conjugation to SMAC mimetic potentiates sigma-2 ligand induced tumor cell death in ovarian cancer

Gynecologic Oncology ◽

10.1016/j.ygyno.2014.03.478 ◽

2014 ◽

Vol 133 ◽

pp. 181

Author(s):

G. Garg ◽

S. Vangveravong ◽

C. Zeng ◽

M.A. Powell ◽

D.G. Mutch ◽

...

Keyword(s):

Ovarian Cancer ◽

Cell Death ◽

Tumor Cell ◽

Tumor Cell Death ◽

Smac Mimetic

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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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Caspase-8 deficiency induces a switch from TLR3 induced apoptosis to lysosomal cell death in neuroblastoma

Scientific Reports ◽

10.1038/s41598-021-89793-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Marie-Anaïs Locquet ◽

Gabriel Ichim ◽

Joseph Bisaccia ◽

Aurelie Dutour ◽

Serge Lebecque ◽

...

Keyword(s):

Cell Death ◽

Cancer Cells ◽

Neuroblastoma Cell ◽

Death Receptor ◽

Neuroblastoma Cell Line ◽

Caspase 8 ◽

Caspase Activation ◽

Extrinsic Pathway ◽

Lysosomal Membrane Permeabilization ◽

Induced Apoptosis

AbstractIn cancer cells only, TLR3 acquires death receptor properties by efficiently triggering the extrinsic pathway of apoptosis with Caspase-8 as apical protease. Here, we demonstrate that in the absence of Caspase-8, activation of TLR3 can trigger a form of programmed cell death, which is distinct from classical apoptosis. When TLR3 was activated in the Caspase-8 negative neuroblastoma cell line SH-SY5Y, cell death was accompanied by lysosomal permeabilization. Despite caspases being activated, lysosomal permeabilization as well as cell death were not affected by blocking caspase-activity, positioning lysosomal membrane permeabilization (LMP) upstream of caspase activation. Taken together, our data suggest that LMP with its deadly consequences represents a “default” death mechanism in cancer cells, when Caspase-8 is absent and apoptosis cannot be induced.

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