scholarly journals Changes in Endoplasmic Reticulum Luminal Environment Affect Cell Sensitivity to Apoptosis

2000 ◽  
Vol 150 (4) ◽  
pp. 731-740 ◽  
Author(s):  
Kimitoshi Nakamura ◽  
Ella Bossy-Wetzel ◽  
Kimberly Burns ◽  
Marc P. Fadel ◽  
Mira Lozyk ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Internal Factor ◽  
Drug Induced ◽  
Cell Sensitivity ◽  
Hela Cell Lines ◽  
Increased Sensitivity ◽  
Low Levels ◽  
Drug Dependent ◽  
Induced Apoptosis

To test the role of ER luminal environment in apoptosis, we generated HeLa cell lines inducible with respect to calreticulin and calnexin and investigated their sensitivity to drug-dependent apoptosis. Overexpression of calreticulin, an ER luminal protein, resulted in an increased sensitivity of the cells to both thapsigargin- and staurosporine-induced apoptosis. This correlated with an increased release of cytochrome c from the mitochondria. Overexpression of calnexin, an integral ER membrane protein, had no significant effect on drug-induced apoptosis. In contrast, calreticulin-deficient cells were significantly resistant to apoptosis and this resistance correlated with a decreased release of cytochrome c from mitochondria and low levels of caspase 3 activity. This work indicates that changes in the lumen of the ER amplify the release of cytochrome c from mitochondria, and increase caspase activity, during drug-induced apoptosis. There may be communication between the ER and mitochondria, which may involve Ca2+ and play an important role in conferring cell sensitivity to apoptosis. Apoptosis may depend on both the presence of external apoptosis-activating signals, and, as shown in this study, on an internal factor represented by the ER.

scholarly journals The role of ARK in stress-induced apoptosis in Drosophila cells

2002 ◽  
Vol 156 (6) ◽  
pp. 1077-1087 ◽  
Author(s):  
Katja C. Zimmermann ◽  
Jean-Ehrland Ricci ◽  
Nathalie M. Droin ◽  
Douglas R. Green
Keyword(s):  
Cell Death ◽  
Cytochrome C ◽  
Molecular Mechanisms ◽  
Mitochondrial Pathway ◽  
Exact Function ◽  
Increased Sensitivity ◽  
Induced Apoptosis ◽  
Drosophila Cells ◽  
Pronounced Inhibition

The molecular mechanisms of apoptosis are highly conserved throughout evolution. The homologs of genes essential for apoptosis in Caenorhabditis elegans and Drosophila melanogaster have been shown to be important for apoptosis in mammalian systems. Although a homologue for CED-4/apoptotic protease-activating factor (Apaf)-1 has been described in Drosophila, its exact function and the role of the mitochondrial pathway in its activation remain unclear. Here, we used the technique of RNA interference to dissect apoptotic signaling pathways in Drosophila cells. Inhibition of the Drosophila CED-4/Apaf-1–related killer (ARK) homologue resulted in pronounced inhibition of stress-induced apoptosis, whereas loss of ARK did not protect the cells from Reaper- or Grim-induced cell death. Reduction of DIAP1 induced rapid apoptosis in these cells, whereas the inhibition of DIAP2 expression did not but resulted in increased sensitivity to stress-induced apoptosis; apoptosis in both cases was prevented by inhibition of ARK expression. Cells in which cytochrome c expression was decreased underwent apoptosis induced by stress stimuli, Reaper or Grim. These results demonstrate the central role of ARK in stress-induced apoptosis, which appears to act independently of cytochrome c. Apoptosis induced by Reaper or Grim can proceed via a distinct pathway, independent of ARK.

Cleavage of Bax to p18 Bax accelerates stress-induced apoptosis, and a cathepsin-like protease may rapidly degrade p18 Bax

Blood ◽  
2003 ◽  
Vol 102 (7) ◽  
pp. 2605-2614 ◽  
Author(s):  
Xuefang Cao ◽  
Xingming Deng ◽  
W. Stratford May
Keyword(s):  
Expression System ◽  
Wild Type ◽  
Mitochondrial Membranes ◽  
Caspase 9 ◽  
Cytochrome C Release ◽  
Drug Induced ◽  
293 Cells ◽  
Increased Sensitivity ◽  
Induced Apoptosis

Abstract Bax is cleaved by calpain at aspartate 33 (Asp33) to yield p18 Bax during stress-induced apoptosis. To assess the role of p18 Bax in apoptosis, an ecdysone-inducible expression system was generated. Similar levels of wild-type (WT) and noncleavable Asp33Ala (Asp→Ala) Bax are induced in 293 cells while expression of N-terminal-deleted p18 (Δ1-33) Bax remains low (20% of full-length p21 Bax) due to a reduced half-life (2 hours versus 12 hours for p21 Bax) resulting from increased sensitivity to cathepsin-like proteolytic degradation. Expression of p18 Bax is enhanced to levels comparable to p21 Bax when induction is carried out in the presence of cathepsin inhibitors, Z-Phe-Gly-NHO-Bz or N-Acetyl-Leu-Leu-Met-CHO. Compared with WT Bax, expression of similar levels of p18 Bax and, surprisingly, Asp33Ala Bax more potently induces apoptosis as indicated by increased cytochrome c release, caspase-9/-3 activation, and DNA fragmentation, potentially due to their increased homo-oligomerization in mitochondrial membranes. Studies in A-549, U-937, K-562, and HL-60 cells confirm that inhibition of Bax cleavage results in 25% to 35% reduction of drug-induced apoptosis, while inhibition of p18 Bax degradation enhances apoptosis by 25% to 40%. Results indicate that although cleavage to p18 Bax is not required for Bax to initiate apoptosis, p18 Bax potently accelerates the apoptotic process. (Blood. 2003;102:2605-2614)

REACTIONS OF DRUG-DEPENDENT ANTIBODIES WITH METABOLITES OF QUININE (Qn) AND QUINIDINE (Qd)

1987 ◽  
Author(s):  
D J Christie ◽  
H Diaz-Arauzo ◽  
J M Cook
Keyword(s):  
Ring Structure ◽  
Quinoline Ring ◽  
Drug Induced ◽  
Group 3 ◽  
Methyl Derivatives ◽  
Drug Dependent ◽  
Group 2 ◽  
Asymmetric Carbon ◽  
Group 1

In many cases of drug-induced immunologic thrombocytopenia (DITP), a metabolite, rather than the native drug, is suspected of provoking the destructive drug-dependent antibodies (DDAB) responsible for this severe hemorrhagic disorder. However, this has not previously been investigated for Qn- and Qd-DDAB. We report evidence that the native drugs, and not their metabolites, are the provocative agents in Qn and Qd DITP. Reactions of Qn- and Qd-DDAB with platelets were studied with the native drugs and four of their metabolites: the N-oxide and 10,11-diol derivatives (quinuclidine ring modifications), the des-methyl derivatives (aromatic quinoline ring modification), and 2'-quininone and 2'-quinidinone (2'-oxo derivatives) (also quinoline ring modifications on Qn and Qd, respectively). Five antibodies were studied:two Group 1 DDAB (specific for compounds with native configuration at asymmetric carbon positions), two Group 2 DDAB (similar to Group 1 DDAB but also known to require the methoxy group on the quinuclidine ring for full activity), and one Group 3 DDAB (reactive with the native drug, its stereoisomer, and several nonmetabolic analogs of both compounds) . Using a complement-dependent 51Cr-lysis assay, the reactions of all DDAB with platelets and the four metabolites were similar to 100-fold weaker when compared to reactions obtained with the native drug, with these exceptions:Group 2 DDAB failed to react with the desmethyl and 2'-oxo metabolites and the Group 3 DDAB failed to react with 2'-oxo Qd. This observation shows that the activity of certain DDAB is critically dependent on the native quinoline ring structure. Importantly, none of the DDAB reacted more strongly with any of the metabolites tested when compared with reactions in the presence of the native drug. These findings indicate that DDAB react with platelets preferentially in the presence of the unaltered Qn and Qd molecules and suggest that, while the role of metabolites cannot be entirely ruled out, the native structure of the drug molecule is sufficient to stimulate production of the antibodies responsible for DITP.

scholarly journals Contribution of Mitochondrial Ion Channels to Chemo-Resistance in Cancer Cells

Cancers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 761 ◽  
Author(s):  
Roberta Peruzzo ◽  
Ildiko Szabo
Keyword(s):  
Ion Channels ◽  
Cytochrome C ◽  
Cancer Cells ◽  
Cytochrome C Release ◽  
Drug Induced ◽  
Point Of No Return ◽  
Different Types ◽  
Subsequent Activation ◽  
Induced Apoptosis ◽  
Potential Efficiency

Mitochondrial ion channels are emerging oncological targets, as modulation of these ion-transporting proteins may impact on mitochondrial membrane potential, efficiency of oxidative phosphorylation and reactive oxygen production. In turn, these factors affect the release of cytochrome c, which is the point of no return during mitochondrial apoptosis. Many of the currently used chemotherapeutics induce programmed cell death causing damage to DNA and subsequent activation of p53-dependent pathways that finally leads to cytochrome c release from the mitochondrial inter-membrane space. The view is emerging, as summarized in the present review, that ion channels located in this organelle may account in several cases for the resistance that cancer cells can develop against classical chemotherapeutics, by preventing drug-induced apoptosis. Thus, pharmacological modulation of these channel activities might be beneficial to fight chemo-resistance of different types of cancer cells.

scholarly journals The role of RelA (p65) threonine 505 phosphorylation in the regulation of cell growth, survival, and migration

2011 ◽  
Vol 22 (17) ◽  
pp. 3032-3040 ◽  
Author(s):  
Aichi Msaki ◽  
Ana M. Sánchez ◽  
Li Fang Koh ◽  
Benjamin Barré ◽  
Sonia Rocha ◽  
...  
Keyword(s):  
Inflammatory Responses ◽  
Cellular Migration ◽  
Negative Regulator ◽  
Drug Induced ◽  
Conserved Residues ◽  
Cellular Processes ◽  
And Migration ◽  
Induced Apoptosis ◽  
Proliferation And Migration

The NF-κB family of transcription factors is a well-established regulator of the immune and inflammatory responses and also plays a key role in other cellular processes, including cell death, proliferation, and migration. Conserved residues in the trans-activation domain of RelA, which can be posttranslationally modified, regulate divergent NF-κB functions in response to different cellular stimuli. Using rela−/−mouse embryonic fibroblasts reconstituted with RelA, we find that mutation of the threonine 505 (T505) phospho site to alanine has wide-ranging effects on NF-κB function. These include previously described effects on chemotherapeutic drug-induced apoptosis, as well as new roles for this modification in autophagy, cell proliferation, and migration. This last effect was associated with alterations in the actin cytoskeleton and expression of cellular migration–associated genes such as WAVE3 and α-actinin 4. We also define a new component of cisplatin-induced, RelA T505–dependent apoptosis, involving induction of NOXA gene expression, an effect explained at least in part through induction of the p53 homologue, p73. Therefore, in contrast to other RelA phosphorylation events, which positively regulate NF-κB function, we identified RelA T505 phosphorylation as a negative regulator of its ability to induce diverse cellular processes such as apoptosis, autophagy, proliferation, and migration.

Regulation of Chemoresistance and Immune Resistance of B-NHL Cell Lines by Overexpression of YY1 and Bcl-xL, Respectively: Reversal of Resistance by Rituximab.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1517-1517
Author(s):  
Mario I. Vega ◽  
Ali R. Jazirehi ◽  
Sara Huerta-Yepez ◽  
Benjamin Bonavida
Keyword(s):  
Tumor Cells ◽  
Cell Lines ◽  
Drug Induced ◽  
Direct Role ◽  
No Donor ◽  
Immune Resistance ◽  
Apoptosis Inhibition ◽  
Immune Mediated ◽  
Induced Apoptosis

Abstract We have recently reported that treatment of B-NHL cell lines with rituximab sensitizes the tumor cells to both chemotherapy and Fas-induced apoptosis (Jazirehi and Bonavida, 2005, Oncogene, 24:2121–2145). This study investigated the underlying molecular mechanism of rituximab-mediated reversal of resistance. Treatment of B-NHL cell lines inhibited the constitutively activated NF- κB. Cells expressing dominant active IκB or treated with NF-κB specific inhibitors were sensitized to both drugs and FasL agonist mAb (CH-11)-induced apoptosis. Downregulation of Bcl-xL expression via inhibition of NF-κB activity correlated with chemosensitivity. The direct role of Bcl-xL in chemoresistance was demonstrated by the use of Bcl-xL overexpressing Ramos cells, Ramos HA-BclxL (gift from Genhong Cheng, UCLA), which were not sensitized by rituximab to drug-induced apoptosis. However, inhibition of Bcl-xL in Ramos HA-Bcl-x resulted in sensitization to drug-induced apoptosis. The role of Bcl-xL expression in the regulation of Fas resistance was not apparent as Ramos HA-Bcl cells were as sensitive as the wild type cells to CH-11-induced apoptosis. Several lines of evidence support the direct role of the transcription repressor Yin-Yang 1 (YY1) in the regulation of resistance to CH-11-induced apoptosis. Inhibition of YY1 activity by either rituximab, the NO donor DETANONOate, or following transfection with YY1 siRNA all resulted in upregulation of Fas expression and sensitization to CH-11-induced apoptosis. These findings suggest two complementary mechanisms underlying the chemo-sensitization and immuno-sensitization of B NHL cells by rituximab via inhibition of NF-κB. The regulation of chemoresistance by NF-κB is mediated via Bcl-xL expression whereas the regulation of Fas resistance by NF-κB is mediated via YY1 expression and activity. These findings suggest that drug-resistant NHL tumor cells may be sensitive to immune-mediated therapeutics.

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