scholarly journals Role of NAD(P)H:quinone oxidoreductase (NQO1) in apoptosis induction by aziridinylbenzoquinones RH1 and MeDZQ.

2005 ◽  
Vol 52 (4) ◽  
pp. 937-942 ◽  
Author(s):  
Ausra Nemeikaite-Ceniene ◽  
Aldona Dringeliene ◽  
Jonas Sarlauskas ◽  
Narimantas Cenas
Keyword(s):  
Regression Analysis ◽  
Redox Cycling ◽  
Apoptosis Induction ◽  
Electron Reduction ◽  
Induced Apoptosis ◽  
Phenylene Diamine

We aimed to characterize the role of NAD(P)H:quinone oxidoreductase (NQO1) in apoptosis induction by antitumour quinones RH1 (2,5-diaziridinyl-3-hydroxymethyl-6-methyl-1,4-benzoquinone) and MeDZQ (2,5-dimethyl-3,6-diaziridinyl-1,4-benzoquinone). Digitonin-permeabilized FLK cells catalyzed NADPH-dependent single- and two-electron reduction of RH1 and MeDZQ. At equitoxic concentrations, RH1 and MeDZQ induced apoptosis more efficiently than the nonalkylating duroquinone or H(2)O(2). The antioxidant N,N'-diphenyl-p-phenylene diamine, desferrioxamine, and the inhibitor of NQO1 dicumarol, protected against apoptosis induction by all compounds investigated, but to a different extent. The results of multiparameter regression analysis indicate that RH1 and MeDZQ most likely induce apoptosis via NQO1-linked formation of alkylating species but not via NQO1-linked redox cycling.

scholarly journals Enzymatic single-electron reduction and aerobic cytotoxicity of tirapazamine and its 1-oxide and nor-oxide metabolites

Chemija ◽  
2018 ◽  
Vol 29 (4) ◽  
Author(s):  
Jonas Šarlauskas ◽  
Aušra Nemeikaitė-Čėnienė ◽  
Audronė Marozienė ◽  
Lina Misevičienė ◽  
Mindaugas Lesanavičius ◽  
...  
Keyword(s):  
Side Effects ◽  
Anticancer Agent ◽  
Redox Cycling ◽  
Nitroaromatic Compounds ◽  
Single Electron ◽  
Reductive Activation ◽  
Cell Nuclei ◽  
Electron Reduction ◽  
Phenylene Diamine

Aerobic cytotoxicity of 3-amino-1,2,4-benzotriazine-1,4-dioxide (tirapazamine, TPZ), a bioreductively activated hypoxia-specific anticancer agent, is responsible for TPZ side effects in chemotherapy. In order to clarify its mechanisms, we examined the aerobic cytotoxicity of TPZ and its main metabolites, 3-amino-1,2,4-benzotriazine-1-oxide and 3-amino-1,2,4-benzotriazine in murine hepatoma MH22a cells, and their reduction by NADPH:cytochrome P-450 reductase (P-450R) and ferredoxin:NADP+ reductase (FNR). Analogous studies of several quinones and nitroaromatic compounds with similar values of single-electron reduction midpoint potentials (E17) were carried out. In single-electron reduction by P-450R and FNR, the reactivity of TPZ and its monoxide was similar to that of quinones and nitroaromatics, and increased with an increase in their E17. The cytotoxicity of TPZ and its metabolites possessed a prooxidant character, because it was partly prevented by an antioxidant N,N’-diphenyl-p-phenylene diamine and desferrioxamine, and potentiated by 1,3-bis(2-chloroethyl)-1-nitrosourea. Importantly, the cytotoxicity of TPZ and, possibly, its 1-N-oxide, was much higher than that of quinones and nitroaromatics with similar values of E17 and redox cycling activities. A possible additional factor in the aerobic cytotoxicity of TPZ is its reductive activation in oxygen-poor cell nuclei, leading to the formation of DNA-damaging species similar to those forming under hypoxia.

scholarly journals Aerobic Cytotoxicity of Aromatic N-Oxides: The Role of NAD(P)H:Quinone Oxidoreductase (NQO1)

2020 ◽  
Vol 21 (22) ◽  
pp. 8754
Author(s):  
Aušra Nemeikaitė-Čėnienė ◽  
Jonas Šarlauskas ◽  
Lina Misevičienė ◽  
Audronė Marozienė ◽  
Violeta Jonušienė ◽  
...  
Keyword(s):  
Human Colon ◽  
Redox Cycling ◽  
Geometric Average ◽  
Hct 116 ◽  
Radical Generation ◽  
Electron Reduction ◽  
Catalyzed Reactions ◽  
Hct 116 Cells ◽  
Derivatives Of

Derivatives of tirapazamine and other heteroaromatic N-oxides (ArN→O) exhibit tumoricidal, antibacterial, and antiprotozoal activities, which are typically attributed to bioreductive activation and free radical generation. In this work, we aimed to clarify the role of NAD(P)H:quinone oxidoreductase (NQO1) in ArN→O aerobic cytotoxicity. We synthesized 9 representatives of ArN→O with uncharacterized redox properties and examined their single-electron reduction by rat NADPH:cytochrome P-450 reductase (P-450R) and Plasmodium falciparum ferredoxin:NADP+ oxidoreductase (PfFNR), and by rat NQO1. NQO1 catalyzed both redox cycling and the formation of stable reduction products of ArN→O. The reactivity of ArN→O in NQO1-catalyzed reactions did not correlate with the geometric average of their activity towards P-450R- and PfFNR, which was taken for the parameter of their redox cycling efficacy. The cytotoxicity of compounds in murine hepatoma MH22a cells was decreased by antioxidants and the inhibitor of NQO1, dicoumarol. The multiparameter regression analysis of the data of this and a previous study (DOI: 10.3390/ijms20184602) shows that the cytotoxicity of ArN→O (n = 18) in MH22a and human colon carcinoma HCT-116 cells increases with the geometric average of their reactivity towards P-450R and PfFNR, and with their reactivity towards NQO1. These data demonstrate that NQO1 is a potentially important target of action of heteroaromatic N-oxides.

scholarly journals Puma cooperates with Bim, the rate-limiting BH3-only protein in cell death during lymphocyte development, in apoptosis induction

2006 ◽  
Vol 203 (13) ◽  
pp. 2939-2951 ◽  
Author(s):  
Miriam Erlacher ◽  
Verena Labi ◽  
Claudia Manzl ◽  
Günther Böck ◽  
Alexandar Tzankov ◽  
...  
Keyword(s):  
Cell Death ◽  
Physiological Role ◽  
B Cell Lymphoma ◽  
Apoptosis Induction ◽  
Induced Apoptosis ◽  
The Individual ◽  
Rate Limiting ◽  
Lymphatic Organs ◽  
Single Knockout

The physiological role of B cell lymphoma 2 (Bcl-2) homology 3–only proteins has been investigated in mice lacking the individual genes identifying rate-limiting roles for Bim (Bcl-2–interacting mediator of cell death) and Puma (p53–up-regulated modulator of apoptosis) in apoptosis induction. The loss of Bim protects lymphocytes from apoptosis induced by cytokine deprivation and deregulated Ca++ flux and interferes with the deletion of autoreactive lymphocytes and the shutdown of immune responses. In contrast, Puma is considered the key mediator of p53-induced apoptosis. To investigate the hypothesis that Bim and Puma have overlapping functions, we generated mice lacking both genes and found that bim−/−/puma−/− animals develop multiple postnatal defects that are not observed in the single knockout mice. Most strikingly, hyperplasia of lymphatic organs is comparable with that observed in mice overexpressing Bcl-2 in all hemopoietic cells exceeding the hyperplasia observed in bim−/− mice. Bim and Puma also have clearly overlapping functions in p53-dependent and -independent apoptosis. Their combined loss promotes spontaneous tumorigenesis, causing the malignancies observed in Bcl-2 transgenic mice, but does not exacerbate the autoimmunity observed in the absence of Bim.

scholarly journals The NEDD8 cycle controlled by NEDP1 upon DNA damage is a regulatory module of the HSP70 ATPase activity

2019 ◽  
Author(s):  
Aymeric P. Bailly ◽  
Aurelien Perrin ◽  
Marina Serrano-Macia ◽  
Chantal Maghames ◽  
Orsolya Leidecker ◽  
...  
Keyword(s):  
Dna Damage ◽  
Atpase Activity ◽  
Apoptosis Induction ◽  
Regulatory Module ◽  
Hsp70 Chaperone ◽  
Response To Stress ◽  
Conjugating Enzymes ◽  
Induced Apoptosis

SummaryUbiquitin and ubiquitin-like chains are finely balanced by the action of conjugating and de-conjugating enzymes. Alterations in this balance trigger signalling events required for the response to stress conditions and are often observed in pathologies. How such changes are detected is not well-understood. We show that upon DNA damage the induction of the de-NEDDylating enzyme NEDP1 restricts the formation of poly-NEDD8 chains, mainly through lysines K11/K48. This promotes APAF1 oligomerisation and apoptosis induction, a step that requires the HSP70 ATPase activity. We found that HSP70 binds to NEDD8 and in vitro, mono-NEDD8 stimulates the ATPase activity of HSP70, counteracted upon poly-NEDDylation. This effect is independent of NEDD8 conjugation onto substrates. The studies identify the HSP70 chaperone as sensor of changes in the NEDD8 cycle, providing mechanistic insights for a cytoplasmic role of NEDD8 in the DNA damage induced apoptosis. They also indicate that the balance between mono- versus poly-NEDDylation is a regulatory module of HSP70 function. The above findings may be important in tumorigenesis, as we find that NEDP1 levels are downregulated in Hepatocellular Carcinoma with concomitant accumulation of NEDD8 conjugates.

Targeting p53 Via JNK Pathway: A Novel Role of RITA for Apoptotic Signaling in Multiple Myeloma

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1836-1836
Author(s):  
Manujendra N Saha ◽  
Hua Jiang ◽  
Yijun Yang ◽  
Xiaoyun Zhu ◽  
Xiaoming Wang ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Signaling Pathway ◽  
Molecular Mechanisms ◽  
Tumor Type ◽  
Apoptosis Induction ◽  
P53 Expression ◽  
Jnk Signaling ◽  
Synergistic Cytotoxicity ◽  
Induced Apoptosis

Abstract Abstract 1836 The low frequency of p53 alterations e.g., mutations/deletions (∼10%) in multiple myeloma (MM) makes this tumor type an ideal candidate for p53-targeted therapies. We have previously reported the anti-myeloma activity of a small molecule RITA. However, the molecular mechanisms underlying the pro-apoptotic effect of RITA are largely undefined. There remain controversies over the notion that RITA increases p53 activity by binding with p53. It is highly possible that that RITA-induced activation of the p53 pathway can also occur in the mechanisms independent of inhibition of the p53-MDM2 interaction. To expore the molecular signaling pathway in RITA-induced apoptosis, we performe μd gμene expression profiling (GEP), by microarray in MM.1S cells treated with RITA or DMSO control. A significant number of genes (∼46) were associated with different types of stress signaling including p53 and c-Jun N-terminal kinase (JNK) signaling. Consistent with GEP data we found that treatment of H929 and MM.1S cells (harboring wild type p53) with RITA resulted in a dose- and time-dependent increase in the phosphorylation of c-Jun (c-Jun-p) along with up-regulation of p53. Furthermore, we examined the binding of c-Jun to the activator protein (AP-1) binding site of the p53 promoter region. Chromatin immunoprecipitation analysis (ChIP) analysis demonstrated that phosphorylated c-Jun antibody immunoprecipitated a significantly increased proportion of the region of the p53 promoter containing AP-1 site in both MM.1S and H929 cells treated with RITA, whereas the control antibody (IgG) failed to precipitate it. Quantitative analysis by PCR showed a ∼5 and 7-fold increase of c-Jun binding to p53 promoter in RITA-treated MM.1S and H929 cells, respectively, in comparison to DMSO-treated cells. In order to clarify the involvement of JNK, we investigated the role of JNK in the regulation of p53-mediated apoptosis induced by RITA in MM cells by using a JNK specific inhibitor, SP-600125. SP600125 abrogated the ability of RITA to up-regulate phosphorylated c-Jun and p53. To further understand specific inhibition of JNK activation, using siRNA approach JNK was selectively knocked down in H929 cells resulting in bloackge of RITA-induced activation of c-Jun and p53. Functionally, apoptosis induction by RITA in H929 cells was inhibited by both SP-600125 and JNK siRNA as evidenced by reduction of cleavage of caspase-3 and PARP and attenuation of the RITA-induced increase of Annexin V-positive cells. On the other hand, p53 transcriptional inhibitor, PFT-α or p53 siRNA not only inhibited the activation of p53 transcriptional targets but also abrogated the activation of c-Jun suggesting the establishment of a positive feedback loop between p53 and JNK. In addition, silencing p53 expression significantly blocked the apoptosis induction by RITA. These results confirm that RITA-induced apoptosis in MM cells is p53-dependent. Furthermore, we examined the combined cytotoxic effect of RITA and dexamethasone (DXM) or CDDO (both of which are known as JNK activators) in H929 and MM.1S cell lines and primary MM samples. Treatment of H929 cells with RITA or DXM alone induced only 10 to 40% cell killing which was synergistically enhanced to 65% (CI, 0.86) and 80% (CI, 0.55), respectively in RITA plus DXM combination. The combination of 5 μM RITA and 1 μM DXM induced a synergistic cytotoxicity (CI=0.81-0.90) in 3 primary MM samples. In MM.1S cells, the combination of 0.5 μM CDDO with either 0.25 or 0.5 μM RITA displayed a synergistic cytotoxic response with a CI value of 0.83 and 0.62, respectively (p<0.05). Finally, RITA demonstrates significant anti-tumor activity in a human plasmacytoma xenograft mouse model. Daily intraperitoneal (i.p.) treatment of RITA (10 mg/kg) decreased tumor growth (∼72% inhibition, p<0.01; at day 12 after treatment; n=4) with no apparent toxicity in mice implanted with H929 cells (5 × 106 cells injected s.c. in SCID mice). These findings reveal a novel mechanism of RITA-induced p53-mediated apoptosis through JNK signaling pathway. Our study also provides the rationale for combination of p53 activating drugs with JNK activators which may offer improved therapeutic strategies in treating MM patients. Disclosures: No relevant conflicts of interest to declare.

Caspase-8 Determines Chemosensitivity of ALL Cells and Mediates Favorable Interactions of Cytotoxic Drugs,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3511-3511
Author(s):  
Harald Ehrhardt ◽  
Irmela Jeremias
Keyword(s):  
Cell Death ◽  
Tumor Cells ◽  
Epigenetic Silencing ◽  
Cytotoxic Drugs ◽  
Caspase 8 ◽  
Apoptosis Induction ◽  
Drug Induced ◽  
Induced Apoptosis

Abstract Abstract 3511 Sensitivity of tumor cells towards chemotherapy mainly determines the prognosis of patients suffering from acute lymphoblastic leukemia (ALL); nevertheless, underlying mechanisms regulating chemo-sensitivity remain poorly understood. Here, we aimed at characterizing the role of Caspase-8 for chemo-sensitivity of B- and T-ALL cells. Several different drugs of routine anti-leukemia therapy were tested in vitro. All drugs that induced cell death also activated and cleaved Caspase-8. Caspase-8 was activated independently from extrinsic apoptosis signaling suggesting a downstream amplifier role of Caspase-8 upon drug-induced apoptosis in ALL cells. Most importantly, Asparaginase, Cyclophosphamide, Dexamethasone and Doxorubicin induced apoptosis in a Caspase-8 dependent manner as knockdown of Caspase-8 inhibited drug-induced apoptosis. Accordingly in primary ALL cells, the protein expression levels of Caspase-8 correlated with cell death sensitivity towards these cytotoxic drugs in vitro. In contrast, Cytarabin, Etoposid and others induced apoptosis via Caspase-8 independent signaling. Thus protein expression of Caspase-8 should be evaluated as a potential biomarker for risk stratification in ALL. The expression of Caspase-8 is frequently downregulated in tumor cells mostly due to epigenetic silencing by promoter hypermethylation. In previous work, we had shown that Methotrexate is able to upregulate the expression of epigenetically downregulated Caspase-8 which is mediated by the transcription factor p53 (Ehrhardt et al, Oncogene 2008). Here we found that Methotrexate (MTX) was able sensitize B- and T-cell leukemia cell lines for apoptosis induction by the Caspase-8 dependent drugs Asparaginase, Cyclophosphamide, Dexamethasone and Doxorubicin. Sensitization by MTX for drug-induced apoptosis was mediated by p53 and Caspase-8 as shown by stable expression of respective small hairpin RNAs introduced by lentiviral transduction. Accoordingly to the data obtained in cell lines, in patient-derived ALL cells with low expression of Caspase-8, MTX sensitized for induction of apoptosis by Asparaginase, Cyclophosphamide, Dexamethasone and Doxorubicin. Transient transfection of siRNA into patient-derived ALL cells revealed that synergistic apoptosis induction by MTX and these drugs was dependent on p53 and Caspase-8. Our results indicate that Caspase-8 is crucial for the high anti-leukemic efficiency of numerous routine cytotoxic drugs and drug combinations. Re-expression of epigenetically downregulated Caspase-8 represents a promising approach to increase efficiency of anti-leukemic therapy. Retrospectively, our data might explain on a molecular level, why clinical empirical studies already revealed a high anti-leukemic efficiency for some of these drug combinations over decades. Routine, decades-known cytotoxic drugs activate signaling mechanisms recognized rather recently such as reversing epigenetic silencing. Disclosures: No relevant conflicts of interest to declare.

The role of cbl family of ubiquitin ligases in gastric cancer exosome-induced apoptosis of Jurkat T cells

2009 ◽  
pp. 1-8
Author(s):  
Jing-Lei Qu ◽  
Xiu-Juan Qu ◽  
Ming-Fang Zhao ◽  
Yue-E Teng ◽  
Ye Zhang ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
T Cells ◽  
Ubiquitin Ligases ◽  
Jurkat T Cells ◽  
Induced Apoptosis

Plasma Levels of Protein S, Protein C, and Factor X: Effects of Sex, Hormonal State and Age

1995 ◽  
Vol 74 (05) ◽  
pp. 1271-1275 ◽  
Author(s):  
C M A Henkens ◽  
V J J Bom ◽  
W van der Schaaf ◽  
P M Pelsma ◽  
C Th Smit Sibinga ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Postmenopausal Women ◽  
Protein C ◽  
Blood Donors ◽  
Premenopausal Women ◽  
Protein S ◽  
The Other ◽  
Factor X ◽  
Normal Ranges

SummaryWe measured total and free protein S (PS), protein C (PC) and factor X (FX) in 393 healthy blood donors to assess differences in relation to sex, hormonal state and age. All measured proteins were lower in women as compared to men, as were levels in premenopausal women as compared to postmenopausal women. Multiple regression analysis showed that both age and subgroup (men, pre- and postmenopausal women) were of significance for the levels of total and free PS and PC, the subgroup effect being caused by the differences between the premenopausal women and the other groups. This indicates a role of sex-hormones, most likely estrogens, in the regulation of levels of pro- and anticoagulant factors under physiologic conditions. These differences should be taken into account in daily clinical practice and may necessitate different normal ranges for men, pre- and postmenopausal women.

Moderating Role of Learning Strategies Between Meta-Cognitive Awareness and Study Habits Among University Students

2019 ◽  
Vol 34 (Spring 2019) ◽  
pp. 215-231
Author(s):  
Mussarat J. Khan ◽  
Seemab Rasheed
Keyword(s):  
Regression Analysis ◽  
Resource Management ◽  
University Students ◽  
Learning Strategies ◽  
Management Strategies ◽  
Cognitive Strategies ◽  
Study Habits ◽  
Good Reliability ◽  
Cognitive Awareness

The purpose of present study is to examine the role of learning strategies as moderator between meta-cognitive awareness and study habits among university students. Sample comprises of 200 students (100 male students and 100 female students) of various universities of Islamabad and Rawalpindi with age ranging from 18-25 years. In order to assess study variables questionnaires were used included Meta-Cognitive Awareness Inventory (Schraw & Dennison, 1994) measuring two-components of meta-cognition that are knowledge and regulation of cognition. Study habits demonstrated by the students were measured by the Study Habits Inventory (Wrenn, 1941). Motivated Strategies for Learning Questionnaire (Pintrich, Smith, Garcia, & McKeachie, 1991) which includes motivation and learning strategies scales. In the present study, only the learning strategies section was utilized, which measures the cognitive strategies and resource management strategies. Results revealed positive correlation between research instruments and are also having good reliability. Regression analysis reflected that meta-cognitive awareness predicts study habits among university students. Regression analysis also suggested that learning strategies including resource management strategies and cognitive strategies significantly moderates the relationship between meta-cognitive awareness and study habits. It is also explored gender differences on learning strategies, meta-cognitive awareness and study habits. Future implications of the study were also discussed.

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