scholarly journals Endoplasmic reticulum stress-induced release and binding of calreticulin from human ovarian cancer cells

2021 ◽  
Author(s):  
Trefa M. Abdullah ◽  
Jacqueline Whatmore ◽  
Edwin Bremer ◽  
Rimantas Slibinskas ◽  
Marek Michalak ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Er Stress ◽  
Cellular Responses ◽  
Ovarian Cancer Cells ◽  
Cellular Distribution ◽  
Cell Surfaces ◽  
Er Chaperone ◽  
Immature Dendritic Cells ◽  
The Difference

Abstract Background Calreticulin (CRT) is an endoplasmic reticulum (ER) chaperone, but can appear surface bound on cancers cells, including ovarian cancers (OC). We investigated at what stage of cell viability, CRT appeared associated with surface of human OC cells. CRT on pre-apoptotic tumour cells is thought to initiate their eradication via a process termed immunogenic cell death (ICD). Methods We treated OC cells with the chemotherapeutic—doxorubicin (DX) known to induce translocation of CRT to some tumour cell surfaces, with and without the ER stressor—thapsigargin (TG)—and/or an ER stress inhibitor—TUDCA. We monitored translocation/release of CRT in pre-apoptotic cells by flow cytometry, immunoblotting and ELISA. We investigated the difference in binding of FITC-CRT to pre-apoptotic, apoptotic and necrotic cells and the ability of extracellular CRT to generate immature dendritic cells from THP-1 monocytes. Results Dx-treatment increased endogenously released CRT and extracellular FITC_CRT binding to human pre-apoptotic OC cells. DX and TG also promoted cell death in OC cells which also increased CRT release. These cellular responses were significantly inhibited by TUDCA, suggesting that ER stress is partially responsible for the changes in CRT cellular distribution. Extracellular CRT induces maturation of THP-1 towards a imDC phenotype, an important component of ICD. Conclusion Collectively, these cellular responses suggest that ER stress is partially responsible for the changes in CRT cellular distribution. ER-stress regulates in part the release and binding of CRT to human OC cells where it may play a role in ICD.

scholarly journals JI017, a Complex Herbal Medication, Induces Apoptosis via the Nox4–PERK–CHOP Axis in Ovarian Cancer Cells

2021 ◽  
Vol 22 (22) ◽  
pp. 12264
Author(s):  
Tae Woo Kim ◽  
Seong-Gyu Ko
Keyword(s):  
Ovarian Cancer ◽  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Er Stress ◽  
Cancer Cells ◽  
Combination Treatment ◽  
Ovarian Cancer Cells ◽  
Mesenchymal Transition ◽  
Diphenylene Iodonium ◽  
Anti Cancer

Many anti-cancer drugs, including paclitaxel and etoposide, have originated and been developed from natural products, and traditional herbal medicines have fewer adverse effects and lesser toxicity than anti-tumor reagents. Therefore, we developed a novel complex herbal medicine, JI017, which mediates endoplasmic reticulum (ER) stress and apoptosis through the Nox4–PERK–CHOP signaling pathway in ovarian cancer cells. JI017 treatment increases the expression of GRP78, ATF4, and CHOP and the phosphorylation of PERK and eIF2α via the upregulation of Nox4. Furthermore, it increases the release of intracellular reactive oxygen species (ROS), the production of intracellular Ca2+, and the activation of exosomal GRP78 and cell lysate GRP78. Combination treatment using the sarco/endoplasmic reticulum Ca2+-ATPase inhibitor thapsigargin (TG) and JI017 reportedly induces increased ER stress and cell death in comparison to the control; however, knockdown experiments of PERK and CHOP indicated suppressed apoptosis and ER stress in JI017-treated ovarian cancer cells. Furthermore, targeting Nox4 using specific siRNA and pharmacological ROS inhibitors, including N-acetylcystein and diphenylene iodonium, blocked apoptosis and ER stress in JI017-treated ovarian cancer cells. In the radioresistant ovarian cancer model, when compared to JI017 alone, JI017 co-treatment with radiation induced greater cell death and resulted in overcoming radioresistance by inhibiting epithelial–mesenchymal-transition-related phenomena such as the reduction of E-cadherin and the increase of N-cadherin, vimentin, Slug, and Snail. These findings suggest that JI017 is a powerful anti-cancer drug for ovarian cancer treatment and that its combination treatment with radiation may be a novel therapeutic strategy for radioresistant ovarian cancer.

Inhibition of Autophagy Potentiated Hippocampal Cell Death Induced by Endoplasmic Reticulum Stress and its Activation by Trehalose Failed to be Neuroprotective

2019 ◽  
Vol 16 (1) ◽  
pp. 3-11
Author(s):  
Luisa Halbe ◽  
Abdelhaq Rami
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Er Stress ◽  
Cell Damage ◽  
Protective Mechanism ◽  
Unfolded Proteins ◽  
Neuronal Viability ◽  
Hippocampal Cell ◽  
Trigger Cell Death ◽  
Autophagy Inhibition

Introduction: Endoplasmic reticulum (ER) stress induced the mobilization of two protein breakdown routes, the proteasomal- and autophagy-associated degradation. During ERassociated degradation, unfolded ER proteins are translocated to the cytosol where they are cleaved by the proteasome. When the accumulation of misfolded or unfolded proteins excels the ER capacity, autophagy can be activated in order to undertake the degradative machinery and to attenuate the ER stress. Autophagy is a mechanism by which macromolecules and defective organelles are included in autophagosomes and delivered to lysosomes for degradation and recycling of bioenergetics substrate. Materials and Methods: Autophagy upon ER stress serves initially as a protective mechanism, however when the stress is more pronounced the autophagic response will trigger cell death. Because autophagy could function as a double edged sword in cell viability, we examined the effects autophagy modulation on ER stress-induced cell death in HT22 murine hippocampal neuronal cells. We investigated the effects of both autophagy-inhibition by 3-methyladenine (3-MA) and autophagy-activation by trehalose on ER-stress induced damage in hippocampal HT22 neurons. We evaluated the expression of ER stress- and autophagy-sensors as well as the neuronal viability. Results and Conclusion: Based on our findings, we conclude that under ER-stress conditions, inhibition of autophagy exacerbates cell damage and induction of autophagy by trehalose failed to be neuroprotective.

scholarly journals Polyhexamethylene Guanidine Phosphate Induces Apoptosis through Endoplasmic Reticulum Stress in Lung Epithelial Cells

2021 ◽  
Vol 22 (3) ◽  
pp. 1215
Author(s):  
Mi Ho Jeong ◽  
Mi Seon Jeon ◽  
Ga Eun Kim ◽  
Ha Ryong Kim
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Epithelial Cell ◽  
Er Stress ◽  
Lung Fibrosis ◽  
A549 Cells ◽  
Polyhexamethylene Guanidine ◽  
Lung Epithelial ◽  
Epithelial Cell Death ◽  
Guanidine Phosphate

Airway epithelial cell death contributes to the pathogenesis of lung fibrosis. Polyhexamethylene guanidine phosphate (PHMG-p), commonly used as a disinfectant, has been shown to be strongly associated with lung fibrosis in epidemiological and toxicological studies. However, the molecular mechanism underlying PHMG-p-induced epithelial cell death is currently unclear. We synthesized a PHMG-p–fluorescein isothiocyanate (FITC) conjugate and assessed its uptake into lung epithelial A549 cells. To examine intracellular localization, the cells were treated with PHMG-p–FITC; then, the cytoplasmic organelles were counterstained and observed with confocal microscopy. Additionally, the organelle-specific cell death pathway was investigated in cells treated with PHMG-p. PHMG-p–FITC co-localized with the endoplasmic reticulum (ER), and PHMG-p induced ER stress in A549 cells and mice. The ER stress inhibitor tauroursodeoxycholic acid (TUDCA) was used as a pre-treatment to verify the role of ER stress in PHMG-p-induced cytotoxicity. The cells treated with PHMG-p showed apoptosis, which was inhibited by TUDCA. Our results indicate that PHMG-p is rapidly located in the ER and causes ER-stress-mediated apoptosis, which is an initial step in PHMG-p-induced lung fibrosis.

scholarly journals Combination of Niraparib, Cisplatin and Twist Knockdown in Cisplatin-Resistant Ovarian Cancer Cells Potentially Enhances Synthetic Lethality through ER-Stress Mediated Mitochondrial Apoptosis Pathway

2021 ◽  
Vol 22 (8) ◽  
pp. 3916
Author(s):  
Entaz Bahar ◽  
Ji-Ye Kim ◽  
Dong-Chul Kim ◽  
Hyun-Soo Kim ◽  
Hyonok Yoon
Keyword(s):  
Ovarian Cancer ◽  
Cell Culture ◽  
Cell Death ◽  
Er Stress ◽  
Cisplatin Resistance ◽  
Cross Resistance ◽  
Ovarian Cancer Cells ◽  
Apoptosis Pathway ◽  
Platinum Based Chemotherapy

Poly (ADP-ribose) polymerase 1 inhibitors (PARPi) are used to treat recurrent ovarian cancer (OC) patients due to greater survival benefits and minimal side effects, especially in those patients with complete or partial response to platinum-based chemotherapy. However, acquired resistance of platinum-based chemotherapy leads to the limited efficacy of PARPi monotherapy in most patients. Twist is recognized as a possible oncogene and contributes to acquired cisplatin resistance in OC cells. In this study, we show how Twist knockdown cisplatin-resistant (CisR) OC cells blocked DNA damage response (DDR) to sensitize these cells to a concurrent treatment of cisplatin as a platinum-based chemotherapy agent and niraparib as a PARPi on in vitro two-dimensional (2D) and three-dimensional (3D) cell culture. To investigate the lethality of PARPi and cisplatin on Twist knockdown CisR OC cells, two CisR cell lines (OV90 and SKOV3) were established using step-wise dose escalation method. In addition, in vitro 3D spheroidal cell model was generated using modified hanging drop and hydrogel scaffolds techniques on poly-2-hydroxylethly methacrylate (poly-HEMA) coated plates. Twist expression was strongly correlated with the expression of DDR proteins, PARP1 and XRCC1 and overexpression of both proteins was associated with cisplatin resistance in OC cells. Moreover, combination of cisplatin (Cis) and niraparib (Nira) produced lethality on Twist-knockdown CisR OC cells, according to combination index (CI). We found that Cis alone, Nira alone, or a combination of Cis+Nira therapy increased cell death by suppressing DDR proteins in 2D monolayer cell culture. Notably, the combination of Nira and Cis was considerably effective against 3D-cultures of Twist knockdown CisR OC cells in which Endoplasmic reticulum (ER) stress is upregulated, leading to initiation of mitochondrial-mediated cell death. In addition, immunohistochemically, Cis alone, Nira alone or Cis+Nira showed lower ki-67 (cell proliferative marker) expression and higher cleaved caspase-3 (apoptotic marker) immuno-reactivity. Hence, lethality of PARPi with the combination of Cis on Twist knockdown CisR OC cells may provide an effective way to expand the therapeutic potential to overcome platinum-based chemotherapy resistance and PARPi cross resistance in OC.

c-Jun Inhibits Thapsigargin-Induced ER Stress Through Up-Regulation of DSCR1/Adapt78

2008 ◽  
Vol 233 (10) ◽  
pp. 1289-1300 ◽  
Author(s):  
Peng Zhao ◽  
Xiaoyan Xiao ◽  
Agnes S. Kim ◽  
M. Fatima Leite ◽  
Jinxia Xu ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Death ◽  
Er Stress ◽  
Wild Type Mouse ◽  
Mouse Fibroblast ◽  
Expression Levels ◽  
Mouse Fibroblasts ◽  
The Unfolded Protein Response ◽  
Calcineurin Activity

The endoplasmic reticulum (ER) is exquisitely sensitive to changes in its internal environment. Various conditions, collectively termed “ER stress”, can perturb ER function, leading to the activation of a complex response known as the unfolded protein response (UPR). Although c-Jun N-terminal kinase (JNK) activation is nearly always associated with cell death by various stimuli, the functional role of JNK in ER stress-induced cell death remains unclear. JNK regulates gene expression through the phosphorylation and activation of transcription factors, such as c-Jun. Here, we investigated the role of c-Jun in the regulation of ER stress-related genes. c-Jun expression levels determined the response of mouse fibroblasts to ER stress induced by thapsigargin (TG, an inhibitor of sarco/endoplasmic reticulum Ca2+ ATPase). c-jun−/− mouse fibroblast cells were more sensitive to TG-induced cell death compared to wild-type mouse fibroblasts, while reconstitution of c-Jun expression in c-jun−/− cells (c-Jun Re) enhanced resistance to TG-induced cell death. The expression levels of ER chaperones Grp78 and Gadd153 induced by TG were lower in c-Jun Re than in c-jun−/− cells. Moreover, TG treatment significantly increased calcineurin activity in c-jun−/− cells, but not in c-Jun Re cells. In c-Jun Re cells, TG induced the expression of Adapt78, also known as the Down syndrome critical region 1 (DSCR1), which is known to block calcineurin activity. Taken together, our findings suggest that c-Jun, a transcription factor downstream of the JNK signaling pathway, up-regulates Adapt78 expression in response to TG-induced ER stress and contributes to protection against TG-induced cell death.

Abstract 590: Increased Endoplasmic Reticulum Stress in Atherosclerotic Plaques Associated With Acute Coronary Syndrome

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Masafumi Myoishi ◽  
Testuo Minamino ◽  
Masafumi Kitakaze
Keyword(s):  
Endoplasmic Reticulum ◽  
Coronary Artery ◽  
Er Stress ◽  
Atherosclerotic Plaques ◽  
Coronary Syndrome ◽  
Er Chaperone ◽  
Unstable Plaques ◽  
Induced Apoptosis ◽  
Stress Dependent ◽  
Dependent Pathway

Background Endoplasmic reticulum (ER) responds to various stresses by up-regulation of ER chaperones, and prolonged ER stress eventually causes apoptosis. Although apoptosis is considered to be essential for the progression and rupture of atherosclerotic plaques, the influence of ER stress and apoptosis on rupture of unstable coronary plaques remains unclear. Methods and Results We obtained 152 coronary artery segments at autopsy and 40 atherectomy specimens from 71 and 40 patients, respectively . Smooth muscle cells (SMCs) and macrophages in the fibrous caps of thin cap atheroma and ruptured plaques, but not in the fibrous caps of thick cap atheroma and fibrous plaques, showed a marked increase in the expression of ER chaperone and numbers of apoptotic cells. ER chaperones also expressed higher in atherectomy specimens from patients with unstable angina pectoris than with stable angina. To explore the plausible molecular mechanism of activation of ER stress and the mechanistic link to apoptosis, we investigated plaque lipids such as oxysterols. Among oxysterols, expression of 7-ketocholesterol was increased in the fibrous caps of thin cap atheroma compared with thick cap atheroma. Treatment of either cultured coronary artery SMCs or THP-1 cells with 7-ketocholesterol induced upregulation of ER chaperones and apoptosis, while these changes were prevented by antioxidants. We also investigated possible signaling pathways for ER-initiated apoptosis and found that the CHOP (a transcription factor induced by ER stress)-dependent pathway was activated in unstable plaques. In addition, knockdown of CHOP expression by siRNA decreased ER stress-dependent death of cultured coronary artery SMCs and THP-1 cells. Conclusions Increased ER stress occurs in unstable plaques. Our findings suggest that ER stress-induced apoptosis of SMCs and macrophages may contribute to plaque vulnerability.

scholarly journals Unification of Opposites between Two Antioxidant Transcription Factors Nrf1 and Nrf2 in Mediating Distinct Cellular Responses to the Endoplasmic Reticulum Stressor Tunicamycin

Antioxidants ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 4 ◽  
Author(s):  
Yu-ping Zhu ◽  
Ze Zheng ◽  
Shaofan Hu ◽  
Xufang Ru ◽  
Zhuo Fan ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Transcription Factor ◽  
Transcription Factors ◽  
Er Stress ◽  
Target Genes ◽  
Cellular Responses ◽  
Water Soluble ◽  
Heme Oxygenase 1 ◽  
Nuclear Factor ◽  
Activating Transcription Factor

The water-soluble Nrf2 (nuclear factor, erythroid 2-like 2, also called Nfe2l2) is accepted as a master regulator of antioxidant responses to cellular stress, and it was also identified as a direct target of the endoplasmic reticulum (ER)-anchored PERK (protein kinase RNA-like endoplasmic reticulum kinase). However, the membrane-bound Nrf1 (nuclear factor, erythroid 2-like 1, also called Nfe2l1) response to ER stress remains elusive. Herein, we report a unity of opposites between these two antioxidant transcription factors, Nrf1 and Nrf2, in coordinating distinct cellular responses to the ER stressor tunicamycin (TU). The TU-inducible transcription of Nrf1 and Nrf2, as well as GCLM (glutamate cysteine ligase modifier subunit) and HO-1 (heme oxygenase 1), was accompanied by activation of ER stress signaling networks. Notably, the unfolded protein response (UPR) mediated by ATF6 (activating transcription factor 6), IRE1 (inositol requiring enzyme 1) and PERK was significantly suppressed by Nrf1α-specific knockout, but hyper-expression of Nrf2 and its target genes GCLM and HO-1 has retained in Nrf1α−/− cells. By contrast, Nrf2−/−ΔTA cells with genomic deletion of its transactivation (TA) domain resulted in significant decreases of GCLM, HO-1 and Nrf1; this was accompanied by partial decreases of IRE1 and ATF6, rather than PERK, but with an increase of ATF4 (activating transcription factor 4). Interestingly, Nrf1 glycosylation and its trans-activity to mediate the transcriptional expression of the 26S proteasomal subunits, were repressed by TU. This inhibitory effect was enhanced by Nrf1α−/− and Nrf2−/−ΔTA, but not by a constitutive activator caNrf2ΔN (that increased abundances of the non-glycosylated and processed Nrf1). Furthermore, caNrf2ΔN also enhanced induction of PERK and IRE1 by TU, but reduced expression of ATF4 and HO-1. Thus, it is inferred that such distinct roles of Nrf1 and Nrf2 are unified to maintain cell homeostasis by a series of coordinated ER-to-nuclear signaling responses to TU. Nrf1α (i.e., a full-length form) acts in a cell-autonomous manner to determine the transcription of most of UPR-target genes, albeit Nrf2 is also partially involved in this process. Consistently, transactivation of ARE (antioxidant response element)-driven BIP (binding immunoglobulin protein)-, PERK- and XBP1 (X-box binding protein 1)-Luc reporter genes was mediated directly by Nrf1 and/or Nrf2. Interestingly, Nrf1α is more potent than Nrf2 at mediating the cytoprotective responses against the cytotoxicity of TU alone or plus tBHQ (tert-butylhydroquinone). This is also further supported by the evidence that the intracellular reactive oxygen species (ROS) levels are increased in Nrf1α−/− cells, but rather are, to our surprise, decreased in Nrf2−/−ΔTA cells.

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