Inhibition of Drp1 Sensitizes Cancer Cells to Cisplatin-Induced Apoptosis through Transcriptional Inhibition of c-FLIP Expression

Mitochondrial fragmentation occurs during the apoptosis. Dynamin-related protein 1 (Drp1) acts as an important component in mitochondrial fission machinery and can regulate various biological processes including apoptosis, cell cycle, and proliferation. The present study demonstrates that dysfunction of mitochondrial dynamics plays a pivotal role in cisplatin-induced apoptosis. Inhibiting the mitochondrial fission with the specific inhibitor (Mdivi-1) did not affect apoptotic cell death in low concentrations (<10 μM). Interestingly, mdivi-1 enhanced cisplatin-induced apoptosis in cancer cells, but not in normal cells. Particularly in the presence of mdivi-1, several human cancer cell lines, including renal carcinoma cell line Caki-1, became vulnerable to cisplatin by demonstrating the traits of caspase 3-dependent apoptosis. Combined treatment induced downregulation of c-FLIP expression transcriptionally, and ectopic expression of c-FLIP attenuated combined treatment-induced apoptotic cell death with mdivi-1 plus cisplatin. Collectively, our data provide evidence that mdivi-1 might be a cisplatin sensitizer.

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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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Abstract 393: MCL-1 Promotes Survival and Influences Mitochondrial Dynamics in Cardiac Myocytes

Circulation Research ◽

10.1161/res.117.suppl_1.393 ◽

2015 ◽

Vol 117 (suppl_1) ◽

Author(s):

Alexandra G Moyzis ◽

Robert L Thomas ◽

Jennifer Kuo ◽

Åsa B Gustafsson

Keyword(s):

Cell Death ◽

Cardiac Myocytes ◽

Apoptotic Cell ◽

Mitochondrial Dynamics ◽

Mitochondrial Fission ◽

Apoptotic Cell Death ◽

Mitochondrial Fusion ◽

Mitochondrial Outer Membrane ◽

Mitochondrial Morphology ◽

Rapid Degradation

The BCL-2 family proteins are important regulators of mitochondrial structure and integrity. MCL-1 is an anti-apoptotic BCL-2 protein that is highly expressed in the myocardium compared to the other anti-apoptotic proteins BCL-2 and BCL-X L. Recently, we reported that MCL-1 is essential for myocardial homeostasis. Cardiac-specific deletion of MCL-1 in mice led to rapid mitochondrial dysfunction, hypertrophy, and lethal cardiomyopathy. Surprisingly, MCL-1 deficient myocytes did not undergo apoptotic cell death. Instead, the cells displayed signs of mitochondrial deterioration and necrotic cell death, suggesting that MCL-1 has an additional role in maintaining mitochondrial function in cardiac myocytes. Similarly, deletion of MCL-1 in fibroblasts caused rapid mitochondrial fragmentation followed by cell death at 72 hours. Interestingly, the MCL-1 deficient fibroblasts retained cytochrome c in the mitochondria , confirming that the cells were not undergoing apoptotic cell death. We have also identified that MCL-1 localizes to the mitochondrial outer membrane (OM) and the matrix in the myocardium and that the two forms respond differently to stress. MCL-1 OM was rapidly degraded after myocardial infarction or fasting, whereas MCL-1 Matrix levels were maintained. Similarly, starvation of MEFs resulted in rapid degradation of MCL-1 OM , whereas MCL-1 Matrix showed delayed degradation. Treatment with the mitochondrial uncoupler FCCP led to rapid degradation of both forms. This suggests that the susceptibility to degradation is dependent on its localization and the nature of the stress. Our data also suggests that these two forms perform distinct functions in regulating mitochondrial morphology and survival. Overexpression of MCL-1 Matrix promoted mitochondrial fusion in fibroblasts under baseline conditions and protected cells against FCCP-mediated mitochondrial fission and clearance by autophagosomes. Thus, our data suggest that MCL-1 exists in two separate locations where it performs different functions. MCL-1 Matrix promotes mitochondrial fusion, which protects cells against excessive mitochondrial clearance during unfavorable conditions.

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Inhibition of cathepsin K sensitizes oxaliplatin-induced apoptotic cell death by Bax upregulation through OTUB1-mediated p53 stabilization in vitro and in vivo

Oncogene ◽

10.1038/s41388-021-02088-7 ◽

2021 ◽

Author(s):

Seung Un Seo ◽

Seon Min Woo ◽

Shin Kim ◽

Jong-Wook Park ◽

Hyun-Shik Lee ◽

...

Keyword(s):

Cell Death ◽

Cancer Cells ◽

Apoptotic Cell ◽

Critical Role ◽

Cathepsin K ◽

Apoptotic Cell Death ◽

Mouse Xenograft Model ◽

Induced Apoptosis ◽

Cathepsin K Inhibition

AbstractCathepsin K is highly expressed in various types of cancers. However, the effect of cathepsin K inhibition in cancer cells is not well characterized. Here, cathepsin K inhibitor (odanacatib; ODN) and knockdown of cathepsin K (siRNA) enhanced oxaliplatin-induced apoptosis in multiple cancer cells through Bax upregulation. Bax knockdown significantly inhibited the combined ODN and oxaliplatin treatment-induced apoptotic cell death. Stabilization of p53 by ODN played a critical role in upregulating Bax expression at the transcriptional level. Casein kinase 2 (CK2)-dependent phosphorylation of OTUB1 at Ser16 played a critical role in ODN- and cathepsin K siRNA-mediated p53 stabilization. Interestingly, ODN-induced p53 and Bax upregulation were modulated by the production of mitochondrial reactive oxygen species (ROS). Mitochondrial ROS scavengers prevented OTUB1-mediated p53 stabilization and Bax upregulation by ODN. These in vitro results were confirmed by in mouse xenograft model, combined treatment with ODN and oxaliplatin significantly reduced tumor size and induced Bax upregulation. Furthermore, human renal clear carcinoma (RCC) tissues revealed a strong correlation between phosphorylation of OTUB1(Ser16) and p53/Bax expression. Our results demonstrate that cathepsin K inhibition enhances oxaliplatin-induced apoptosis by increasing OTUB1 phosphorylation via CK2 activation, thereby promoting p53 stabilization, and hence upregulating Bax.

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HSP70 Acetylation Prevents Combined mTORC1/2 Inhibitor and Curcumin Treatment-Induced Apoptosis

Molecules ◽

10.3390/molecules23112755 ◽

2018 ◽

Vol 23 (11) ◽

pp. 2755 ◽

Cited By ~ 1

Author(s):

Seung Seo ◽

Kyoung-jin Min ◽

Seon Woo ◽

Ji Seo ◽

Taeg Kwon

Keyword(s):

Cell Death ◽

Er Stress ◽

Apoptotic Cell ◽

Combined Treatment ◽

Apoptotic Cell Death ◽

Curcumin Treatment ◽

Dual Inhibitor ◽

Acetylation Site ◽

Induced Apoptosis ◽

The Relationship

We previously reported that PP242 (dual inhibitor of mTORC1/2) plus curcumin induced apoptotic cell death through lysosomal membrane permeabilization (LMP)-mediated autophagy. However, the relationship between ER stress and apoptotic cell death by combined PP242 and curcumin treatment remains unknown. In the present study, we found that combined PP242 and curcumin treatment induced cytosolic Ca2+ release and ER stress. Interestingly, pretreatment with the chemical chaperones (TUDCA and 4-PBA) and knockdown of CHOP and ATF4 by siRNA did not abolish combined treatment-induced apoptosis in renal carcinoma cells. These results suggest that combined treatment with mTORC1/2 inhibitor and curcumin induces ER stress which is not essential for apoptotic cell death. Furthermore, overexpression of HSP70 significantly inhibited PP242 plus curcumin-induced LMP and apoptosis, but the protective effect was abolished by K77R mutation of acetylation site of HSP70. Taken together, our results reveal that regulation of HSP70 through K77 acetylation plays role in combined PP242 and curcumin treatment-induced apoptosis.

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BAG3 Promoted Starvation-Induced Apoptosis of Thyroid Cancer Cells via Attenuation of Autophagy

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jc.2014-1779 ◽

2014 ◽

Vol 99 (11) ◽

pp. E2298-E2307 ◽

Cited By ~ 17

Author(s):

Si Li ◽

Hai-Yan Zhang ◽

Tian Wang ◽

Xin Meng ◽

Zhi-Hong Zong ◽

...

Keyword(s):

Cell Death ◽

Thyroid Cancer ◽

Western Blot ◽

Cancer Cells ◽

Real Time ◽

Apoptotic Cell ◽

Apoptotic Cell Death ◽

Complete Medium ◽

Induced Apoptosis ◽

Thyroid Cancer Cells

Context: BAG3 plays a regulatory role in a number of cellular processes. Recent studies have attracted much attention on its role in activation of selective autophagy. In addition, we have very recently reported that BAG3 is implicated in a BECN1-independent autophagy, namely noncanonical autophagy. Objective: The current study aimed to investigate the potential involvement of BAG3 in canonical autophagy triggered by Earle's Balanced Salt Solution (EBSS) starvation. Setting and Design: Replacement of complete medium with EBSS was used to trigger canonical autophagy. BAG3 expression was measured using real-time RT-PCR and Western blot. Autophagy was monitored using LC3-II transition and p62/SQSTM1 accumulation by Western blot, as well as punctate distribution of LC3 by immunofluorescence staining. Cell growth and apoptotic cell death was investigated using real-time cell analyzer and flowcytometry, respectively. Results: BAG3 expression was potently reduced by EBSS starvation. Forced expression of BAG3 suppressed autophagy and promoted apoptotic cell death of thyroid cancer cells elicited by starvation. In addition, in the presence of autophagy inhibitor, the enhancing effect of BAG3 on apoptotic cell death was attenuated. Conclusions: These results suggest that BAG3 promotes apoptotic cell death in starved thyroid cancer cells, at least in part by autophagy attenuation.

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Ouabain Induces Apoptosis on PHA-Activated Lymphocytes

Bioscience Reports ◽

10.1023/a:1022259832207 ◽

1998 ◽

Vol 18 (1) ◽

pp. 1-7 ◽

Cited By ~ 40

Author(s):

Beni Olej ◽

Neusa F. dos Santos ◽

Ludmila Leal ◽

Vivian M. Rumjanek

Keyword(s):

Cell Death ◽

Immune System ◽

Apoptotic Cell ◽

Critical Role ◽

Specific Inhibitor ◽

Apoptotic Cell Death ◽

Pharmacological Intervention ◽

Activated Lymphocytes ◽

Induced Apoptosis ◽

Genomic Response

Apoptotic cell death plays a critical role in immune system homeostasis, and c-myc protooncogene deregulated expression is a component of this programmed genomic response. Pharmacological intervention and modulation of peripheral lymphocytes apoptosis would have important implications. The present results indicate that ouabain, a specific inhibitor of Na+ K+-ATPase, promotes an increased expression of c-myc mRNA, and induces apoptosis in PHA-stimulated lymphocytes. Furthermore, this ouabain-induced apoptosis cannot be counteracted by the addition of exogenous IL-2.

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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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