scholarly journals p62/SQSTM1-induced caspase-8 aggresomes are essential for ionizing radiation-mediated apoptosis

2021 ◽  
Vol 12 (11) ◽  
Author(s):  
Su Hyun Lee ◽  
Won Jin Cho ◽  
Abdo J. Najy ◽  
Allen-Dexter Saliganan ◽  
Tri Pham ◽  
...  
Keyword(s):  
Ionizing Radiation ◽  
Cell Fate ◽  
Apoptotic Cell ◽  
Hpv Infection ◽  
Caspase 8 ◽  
Autophagic Flux ◽  
Sequestosome 1 ◽  
Small Molecule Ligands ◽  
Radiation Treatments ◽  
Induced Apoptosis

AbstractThe autophagy–lysosome pathway and apoptosis constitute vital determinants of cell fate and engage in a complex interplay in both physiological and pathological conditions. Central to this interplay is the archetypal autophagic cargo adaptor p62/SQSTM1/Sequestosome-1 which mediates both cell survival and endoplasmic reticulum stress-induced apoptosis via aggregation of ubiquitinated caspase-8. Here, we investigated the role of p62-mediated apoptosis in head and neck squamous cell carcinoma (HNSCC), which can be divided into two groups based on human papillomavirus (HPV) infection status. We show that increased autophagic flux and defective apoptosis are associated with radioresistance in HPV(-) HNSCC, whereas HPV(+) HNSCC fail to induce autophagic flux and readily undergo apoptotic cell death upon radiation treatments. The degree of radioresistance and tumor progression of HPV(-) HNSCC respectively correlated with autophagic activity and cytosolic levels of p62. Pharmacological activation of the p62-ZZ domain using small molecule ligands sensitized radioresistant HPV(-) HNSCC cells to ionizing radiation by facilitating p62 self-polymerization and sequestration of cargoes leading to apoptosis. The self-polymerizing activity of p62 was identified as the essential mechanism by which ubiquitinated caspase-8 is sequestered into aggresome-like structures, without which irradiation fails to induce apoptosis in HNSCC. Our results suggest that harnessing p62-dependent sequestration of ubiquitinated caspase-8 provides a novel therapeutic avenue in patients with radioresistant tumors.

scholarly journals Inhibition of autophagy triggers melatonin-induced apoptosis in glioblastoma cells

2019 ◽  
Author(s):  
Nan Zhou ◽  
Zixuan Wei ◽  
Zengxin Qi
Keyword(s):  
Direct Evidence ◽  
Apoptotic Cell ◽  
Early Stage ◽  
Autophagic Flux ◽  
Bafilomycin A1 ◽  
Melatonin Receptor ◽  
Glioblastoma Cells ◽  
Human Glioma Cells ◽  
Melatonin Treatment ◽  
Induced Apoptosis

Abstract Background: Autophagy is considered to be another restorative focus for the treatment of brain tumors. Although several research have demonstrated that melatonin induces autophagy in colon cancer and hepatoma cells, there has not been any direct evidence of whether melatonin is capable of inducing autophagy in human glioma cells. Results: In the present research, we report that melatonin or its agonist, agomelatine, induced autophagy in A172 and U87-MG glioblastoma cells for a concentration-and time-dependent way, which was significantly attenuated by treatment with luzindole, a melatonin receptor antagonist. Furthermore, by suppressing autophagy at the late-stage with bafilomycin A1 and early stage with 3-MA, we found that the melatonin-induced autophagy was activated early, and the autophagic flux was complete. Melatonin treatment alone did not induce any apoptotic changes in the glioblastoma cells, as measured by flow cytometry. Western blot studies confirmed that melatonin alone prominently upregulated the levels of Beclin 1 and LC3 II, which was accompanied by an increase in the expression of Bcl-2, whereas it had no effect on the expression of Bax in the glioblastoma cells. Remarkably, co-treatment with 3-MA and melatonin significantly enhanced the apoptotic cell population in the glioblastoma cells, along with a prominent decrease in the expression of bcl-2 and increase in the Bax expression levels, which collectively indicated that the disruption of autophagy triggers the melatonin-induced apoptosis in glioblastoma cells. Conclusions: These results provide information indicating that melatonin may act as a common upstream signal between autophagy and apoptosis, which may lead to the development of new therapeutic strategies for glioma.

scholarly journals Opposing unfolded-protein-response signals converge on death receptor 5 to control apoptosis

Science ◽  
2014 ◽  
Vol 345 (6192) ◽  
pp. 98-101 ◽  
Author(s):  
Min Lu ◽  
David A. Lawrence ◽  
Scot Marsters ◽  
Diego Acosta-Alvear ◽  
Philipp Kimmig ◽  
...  
Keyword(s):  
Er Stress ◽  
Unfolded Protein Response ◽  
Cell Fate ◽  
Apoptotic Cell ◽  
Death Receptor ◽  
Caspase 8 ◽  
Death Receptor 5 ◽  
Unfolded Protein ◽  
The Unfolded Protein Response ◽  
Protein Response

Protein folding by the endoplasmic reticulum (ER) is physiologically critical; its disruption causes ER stress and augments disease. ER stress activates the unfolded protein response (UPR) to restore homeostasis. If stress persists, the UPR induces apoptotic cell death, but the mechanisms remain elusive. Here, we report that unmitigated ER stress promoted apoptosis through cell-autonomous, UPR-controlled activation of death receptor 5 (DR5). ER stressors induced DR5 transcription via the UPR mediator CHOP; however, the UPR sensor IRE1α transiently catalyzed DR5 mRNA decay, which allowed time for adaptation. Persistent ER stress built up intracellular DR5 protein, driving ligand-independent DR5 activation and apoptosis engagement via caspase-8. Thus, DR5 integrates opposing UPR signals to couple ER stress and apoptotic cell fate.

Alterations in the rat forebrain apoptosis following exposure to ionizing radiation

Biologia ◽  
2011 ◽  
Vol 66 (4) ◽  
Author(s):  
Soňa Bálentová ◽  
Eva Hajtmanová ◽  
Yvetta Mellová ◽  
Ľudmila Bošelová ◽  
Elena Fuseková ◽  
...  
Keyword(s):  
Ionizing Radiation ◽  
Apoptotic Cell ◽  
Adult Brain ◽  
Whole Body ◽  
Initial Increase ◽  
Normal Brain ◽  
Factors Affecting ◽  
Male Wistar Rats ◽  
Radiation Induced ◽  
Induced Apoptosis

AbstractIonizing radiation commonly used in the radiotherapy of brain tumours can cause adverse side effects to surrounding normal brain tissue. The most significant response of adult brain to radiation damage is induction of apoptosis. The adult mammalian subventricular zone (SVZ) of the brain lateral ventricles (LV) and their subsequent lateral ventricular extension, the rostral migratory stream (RMS), is one of the few areas, which retains the ability to generate new neurons and glial cells throughout life. Taking into account the fact, that ionizing radiation is one of the strongest exogenous factors affecting cell proliferation, the aim of the present study was to investigate the occurrence of radiation-induced apoptosis in this neurogenic region. Adult male Wistar rats were investigated 1, 5 or 10 days after single whole-body gamma irradiation with the dose of 3 Gy. Apoptotic cell death was determined by in situ labelling of DNA nick ends (TUNEL) and fluorescence microscopy evaluation of TUNEL-positive cells. Considerable increase of apoptotic TUNEL-positive cells was observed 24 hrs after irradiation in caudal parts of RMS; i.e. in the vertical arm and elbow of RMS. Initial increase was followed by strong reduction of apoptosis in the RMS and by secondary over-accumulation of apoptotic cells in the animals that survived ten days after exposure. Results showed, that the proliferating population of cells, arisen in SVZ are highly sensitive to radiation-induced apoptosis. This observation should have implications for clinical radiotherapy to avoid complications in therapeutic brain irradiation.

scholarly journals Inhibition of autophagy triggers melatonin-induced apoptosis in glioblastoma cells

2019 ◽  
Author(s):  
Nan Zhou ◽  
Zixuan Wei ◽  
Zengxin Qi
Keyword(s):  
Direct Evidence ◽  
Apoptotic Cell ◽  
Early Stage ◽  
Autophagic Flux ◽  
Bafilomycin A1 ◽  
Melatonin Receptor ◽  
Glioblastoma Cells ◽  
Human Glioma Cells ◽  
Melatonin Treatment ◽  
Induced Apoptosis

Abstract Background: Autophagy is considered to beanother restorative focus for the treatment of brain tumors. Although several research have demonstrated that melatonin induces autophagy in colon cancer and hepatoma cells, there has not been any direct evidence of whether melatonin is capable of inducing autophagy in human glioma cells. Results: In the present research, we report that melatonin or its agonist, agomelatine, induced autophagy inA172 and U87-MG glioblastoma cells for a concentration-and time-dependent way, whichwas significantly attenuated by treatment with luzindole, a melatonin receptor antagonist. Furthermore, by suppressing autophagy at the late-stage with bafilomycin A1 and early stage with 3-MA, we found that the melatonin-induced autophagy was activated early, and the autophagic flux was complete. Melatonin treatment alone did not induce any apoptotic changes in the glioblastoma cells, as measured by flow cytometry. Western blot studies confirmed that melatonin alone prominently upregulated the levels of Beclin 1 and LC3 II, which was accompanied by an increase in the expression of Bcl-2, whereas it had no effect on the expression of Bax in the glioblastoma cells. Remarkably, co-treatment with 3-MA and melatonin significantly enhanced the apoptotic cell population in the glioblastoma cells, along with a prominent decrease in the expression of bcl-2 and increase in the Bax expression levels, which collectively indicated that the disruption of autophagy triggers the melatonin-induced apoptosis in glioblastoma cells. Conclusions: These results provide information indicating that melatonin may act as a common upstream signal between autophagy and apoptosis, which may lead to the development of new therapeutic strategies for glioma.

scholarly journals Inhibition of autophagy triggers melatonin-induced apoptosis in glioblastoma cells

2019 ◽  
Author(s):  
Nan Zhou ◽  
Zixuan Wei ◽  
Zengxin Qi
Keyword(s):  
Direct Evidence ◽  
Apoptotic Cell ◽  
Early Stage ◽  
Autophagic Flux ◽  
Bafilomycin A1 ◽  
Melatonin Receptor ◽  
Glioblastoma Cells ◽  
Human Glioma Cells ◽  
Melatonin Treatment ◽  
Induced Apoptosis

Abstract Background: Autophagy is considered to be another restorative focus for the treatment of brain tumors. Although several research have demonstrated that melatonin induces autophagy in colon cancer and hepatoma cells, there has not been any direct evidence of whether melatonin is capable of inducing autophagy in human glioma cells. Results: In the present research, we report that melatonin or its agonist, agomelatine, induced autophagy in A172 and U87-MG glioblastoma cells for a concentration-and time-dependent way, which was significantly attenuated by treatment with luzindole, a melatonin receptor antagonist. Furthermore, by suppressing autophagy at the late-stage with bafilomycin A1 and early stage with 3-MA, we found that the melatonin-induced autophagy was activated early, and the autophagic flux was complete. Melatonin treatment alone did not induce any apoptotic changes in the glioblastoma cells, as measured by flow cytometry. Western blot studies confirmed that melatonin alone prominently upregulated the levels of Beclin 1 and LC3 II, which was accompanied by an increase in the expression of Bcl-2, whereas it had no effect on the expression of Bax in the glioblastoma cells. Remarkably, co-treatment with 3-MA and melatonin significantly enhanced the apoptotic cell population in the glioblastoma cells, along with a prominent decrease in the expression of bcl-2 and increase in the Bax expression levels, which collectively indicated that the disruption of autophagy triggers the melatonin-induced apoptosis in glioblastoma cells. Conclusions: These results provide information indicating that melatonin may act as a common upstream signal between autophagy and apoptosis, which may lead to the development of new therapeutic strategies for glioma.

scholarly journals Inhibition of autophagy triggers melatonin-induced apoptosis in glioblastoma cells

2019 ◽  
Author(s):  
Nan Zhou ◽  
Zixuan Wei ◽  
Zengxin Qi
Keyword(s):  
Direct Evidence ◽  
Apoptotic Cell ◽  
Early Stage ◽  
Autophagic Flux ◽  
Bafilomycin A1 ◽  
Melatonin Receptor ◽  
Glioblastoma Cells ◽  
Human Glioma Cells ◽  
Melatonin Treatment ◽  
Induced Apoptosis

Abstract Background: Autophagy is considered to beanother restorative focus for the treatment of brain tumors. Although several research have demonstrated that melatonin induces autophagy in colon cancer and hepatoma cells, there has not been any direct evidence of whether melatonin is capable of inducing autophagy in human glioma cells. Results: In the present research, we report that melatonin or its agonist, agomelatine, induced autophagy inA172 and U87-MG glioblastoma cells for a concentration-and time-dependent way, whichwas significantly attenuated by treatment with luzindole, a melatonin receptor antagonist. Furthermore, by suppressing autophagy at the late-stage with bafilomycin A1 and early stage with 3-MA, we found that the melatonin-induced autophagy was activated early, and the autophagic flux was complete. Melatonin treatment alone did not induce any apoptotic changes in the glioblastoma cells, as measured by flow cytometry. Western blot studies confirmed that melatonin alone prominently upregulated the levels of Beclin 1 and LC3 II, which was accompanied by an increase in the expression of Bcl-2, whereas it had no effect on the expression of Bax in the glioblastoma cells. Remarkably, co-treatment with 3-MA and melatonin significantly enhanced the apoptotic cell population in the glioblastoma cells, along with a prominent decrease in the expression of bcl-2 and increase in the Bax expression levels, which collectively indicated that the disruption of autophagy triggers the melatonin-induced apoptosis in glioblastoma cells. Conclusions: These results provide information indicating that melatonin may act as a common upstream signal between autophagy and apoptosis, which may lead to the development of new therapeutic strategies for glioma.

scholarly journals Inhibition of autophagy triggers melatonin-induced apoptosis in glioblastoma cells

2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Nan Zhou ◽  
Zi Xuan Wei ◽  
Zeng Xin Qi
Keyword(s):  
Direct Evidence ◽  
Apoptotic Cell ◽  
Early Stage ◽  
Autophagic Flux ◽  
Bafilomycin A1 ◽  
Melatonin Receptor ◽  
Glioblastoma Cells ◽  
Human Glioma Cells ◽  
Melatonin Treatment ◽  
Induced Apoptosis

Abstract Background Autophagy is considered to be another restorative focus for the treatment of brain tumors. Although several research have demonstrated that melatonin induces autophagy in colon cancer and hepatoma cells, there has not been any direct evidence of whether melatonin is capable of inducing autophagy in human glioma cells. Results In the present research, we report that melatonin or its agonist, agomelatine, induced autophagy in A172 and U87-MG glioblastoma cells for a concentration-and time-dependent way, which was significantly attenuated by treatment with luzindole, a melatonin receptor antagonist. Furthermore, by suppressing autophagy at the late-stage with bafilomycin A1 and early stage with 3-MA, we found that the melatonin-induced autophagy was activated early, and the autophagic flux was complete. Melatonin treatment alone did not induce any apoptotic changes in the glioblastoma cells, as measured by flow cytometry. Western blot studies confirmed that melatonin alone prominently upregulated the levels of Beclin 1 and LC3 II, which was accompanied by an increase in the expression of Bcl-2, whereas it had no effect on the expression of Bax in the glioblastoma cells. Remarkably, co-treatment with 3-MA and melatonin significantly enhanced the apoptotic cell population in the glioblastoma cells, along with a prominent decrease in the expression of bcl-2 and increase in the Bax expression levels, which collectively indicated that the disruption of autophagy triggers the melatonin-induced apoptosis in glioblastoma cells. Conclusions These results provide information indicating that melatonin may act as a common upstream signal between autophagy and apoptosis, which may lead to the development of new therapeutic strategies for glioma.

scholarly journals The pseudo-caspase FLIP(L) regulates cell fate following p53 activation

2020 ◽  
Vol 117 (30) ◽  
pp. 17808-17819 ◽  
Author(s):  
Andrea Lees ◽  
Alexander J. McIntyre ◽  
Nyree T. Crawford ◽  
Fiammetta Falcone ◽  
Christopher McCann ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Cell Fate ◽  
Target Genes ◽  
Caspase 8 ◽  
Cycle Arrest ◽  
P53 Activation ◽  
Induced Apoptosis

p53 is the most frequently mutated, well-studied tumor-suppressor gene, yet the molecular basis of the switch from p53-induced cell-cycle arrest to apoptosis remains poorly understood. Using a combination of transcriptomics and functional genomics, we unexpectedly identified a nodal role for the caspase-8 paralog and only human pseudo-caspase, FLIP(L), in regulating this switch. Moreover, we identify FLIP(L) as a direct p53 transcriptional target gene that is rapidly up-regulated in response to Nutlin-3A, an MDM2 inhibitor that potently activates p53. Genetically or pharmacologically inhibiting expression of FLIP(L) using siRNA or entinostat (a clinically relevant class-I HDAC inhibitor) efficiently promoted apoptosis in colorectal cancer cells in response to Nutlin-3A, which otherwise predominantly induced cell-cycle arrest. Enhanced apoptosis was also observed when entinostat was combined with clinically relevant, p53-activating chemotherapy in vitro, and this translated into enhanced in vivo efficacy. Mechanistically, FLIP(L) inhibited p53-induced apoptosis by blocking activation of caspase-8 by the TRAIL-R2/DR5 death receptor; notably, this activation was not dependent on receptor engagement by its ligand, TRAIL. In the absence of caspase-8, another of its paralogs, caspase-10 (also transcriptionally up-regulated by p53), induced apoptosis in Nutlin-3A-treated, FLIP(L)-depleted cells, albeit to a lesser extent than in caspase-8-proficient cells. FLIP(L) depletion also modulated transcription of canonical p53 target genes, suppressing p53-induced expression of the cell-cycle regulator p21 and enhancing p53-induced up-regulation of proapoptotic PUMA. Thus, even in the absence of caspase-8/10, FLIP(L) silencing promoted p53-induced apoptosis by enhancing PUMA expression. Thus, we report unexpected, therapeutically relevant roles for FLIP(L) in determining cell fate following p53 activation.

scholarly journals Comparison of S-nitrosoglutathione- and staurosporine-induced apoptosis in human neural cells

2014 ◽  
Vol 92 (12) ◽  
pp. 1001-1011 ◽  
Author(s):  
Caroline Sodja ◽  
Maria Ribecco-Lutkiewicz ◽  
Julie Haukenfrers ◽  
Fahar Merchant ◽  
Willard J. Costain ◽  
...  
Keyword(s):  
Cell Fate ◽  
Cell Lines ◽  
Apoptotic Cell ◽  
Neural Cell ◽  
Neural Cells ◽  
Short Term Exposure ◽  
Induced Apoptosis ◽  
Apoptosis Inducing Agents ◽  
Neural Cell Fate ◽  
Apoptotic Effects

S-nitrosoglutathione (GSNO) is an endogenously produced S-nitrosylating compound that controls the function of various proteins. While a number of rodent cell lines have been used to study GSNO-induced apoptosis, the mechanisms of action remain to be evaluated in human cells and in parallel with other common apoptosis-inducing agents. In this study, we compared the pro-apoptotic effects of GSNO and staurosporine (STS) on human neural progenitors (NT2, hNP1) and neuroblasts (SH-SY5Y). We show that these cells exhibit comparable levels of susceptibility to GSNO- and STS-induced apoptotic cell death, as demonstrated by condensed nuclei and CASP3 activation. Mechanistic differences in apoptotic responses were observed as differential patterns of DNA fragmentation and levels of BAX, BCL-XL, CASP8, and p-ERK in response to GSNO and STS treatment. Mitochondrial membrane potential analysis revealed that NT2 and hNP1 cells, but not SH-SY5Y cells, undergo mitochondrial hyperpolarization in response to short-term exposure to STS prior to undergoing subsequent depolarization. This is the first study to report differences in apoptotic responses to GSNO and STS in 3 complementary human neural cell lines. Furthermore, these cells represent useful tools in cell pharmacological paradigms in which susceptibility to apoptosis-inducing agents needs to be assessed at different stages of neural cell fate commitment and differentiation.

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