Induction of oxidative stress and apoptosis in myeloma cells by the aziridine-containing agent imexon

Katerina Dvorakova, Claire M. Payne, Margaret E Tome, Margaret M Briehl, Thomas McClure, Robert T Dorr

Research output: Contribution to journalArticle

73 Citations (Scopus)

Abstract

Imexon is an iminopyrrolidone derivative that has selective antitumor activity in multiple myeloma. The exact mechanism of imexon action is unknown. In human 8226 myeloma cells, the cytotoxicity of imexon was schedule-dependent, and long exposures (≥48 hr) to low concentrations of imexon were most effective at inducing cytotoxicity. Our data suggest that imexon does not affect DNA, but it can alkylate thiols by binding to the sulfhydryl group. We have also demonstrated by HPLC studies that in human 8226 myeloma cells, imexon depletes cellular stores of cysteine and glutathione. Oxidative stress in 8226 cells exposed to imexon was detected by immunohistochemical staining with a monoclonal antibody to 8-hydroxydeoxyguanosine (8-OHdG), followed by confocal microscopy. These images showed increased levels of 8-OHdG in the cytoplasm of cells treated with different concentrations of imexon at 8, 16, and 48 hr. Interestingly, 8-OHdG staining was not observed in the nuclei of imexon-treated cells, in contrast to the diffuse staining seen with t-butyl hydroperoxide. Myeloma cells exposed to imexon showed classic morphologic features of apoptosis upon electron microscopy, and increased levels of phosphatidylserine exposure, detected as Annexin-V binding, on the cell surface. To prevent depletion of thiols, 8226 myeloma cells exposed to imexon were treated with N-acetylcysteine (NAC). Simultaneous, as well as sequential, treatment with NAC before imexon exposure resulted in protection of myeloma cells against imexon-induced cytotoxicity. Conversely, the glutathione synthesis inhibitor buthionine sulfoximine increased imexon cytotoxicity. These data suggest that imexon perturbs cellular thiols and induces oxidative stress leading to apoptosis in human myeloma cells. (C) 2000 Elsevier Science Inc.

Original languageEnglish (US)
Pages (from-to)749-758
Number of pages10
JournalBiochemical Pharmacology
Volume60
Issue number6
DOIs
StatePublished - Sep 15 2000

Fingerprint

Oxidative stress
Oxidative Stress
Apoptosis
Cytotoxicity
Sulfhydryl Compounds
Acetylcysteine
4-imino-1,3-diazabicyclo(3.1.0)hexan-2-one
aziridine
Staining and Labeling
Glutathione
Buthionine Sulfoximine
tert-Butylhydroperoxide
Cytoprotection
Confocal microscopy
Annexin A5
Phosphatidylserines
Multiple Myeloma
Confocal Microscopy
Electron microscopy

Keywords

  • Apoptosis
  • Cyanoaziridine
  • Imexon
  • Multiple myeloma
  • Oxidative stress

ASJC Scopus subject areas

  • Pharmacology

Cite this

Induction of oxidative stress and apoptosis in myeloma cells by the aziridine-containing agent imexon. / Dvorakova, Katerina; Payne, Claire M.; Tome, Margaret E; Briehl, Margaret M; McClure, Thomas; Dorr, Robert T.

In: Biochemical Pharmacology, Vol. 60, No. 6, 15.09.2000, p. 749-758.

Research output: Contribution to journalArticle

@article{179d39dd0dc1487aa64fb7791e22afeb,
title = "Induction of oxidative stress and apoptosis in myeloma cells by the aziridine-containing agent imexon",
abstract = "Imexon is an iminopyrrolidone derivative that has selective antitumor activity in multiple myeloma. The exact mechanism of imexon action is unknown. In human 8226 myeloma cells, the cytotoxicity of imexon was schedule-dependent, and long exposures (≥48 hr) to low concentrations of imexon were most effective at inducing cytotoxicity. Our data suggest that imexon does not affect DNA, but it can alkylate thiols by binding to the sulfhydryl group. We have also demonstrated by HPLC studies that in human 8226 myeloma cells, imexon depletes cellular stores of cysteine and glutathione. Oxidative stress in 8226 cells exposed to imexon was detected by immunohistochemical staining with a monoclonal antibody to 8-hydroxydeoxyguanosine (8-OHdG), followed by confocal microscopy. These images showed increased levels of 8-OHdG in the cytoplasm of cells treated with different concentrations of imexon at 8, 16, and 48 hr. Interestingly, 8-OHdG staining was not observed in the nuclei of imexon-treated cells, in contrast to the diffuse staining seen with t-butyl hydroperoxide. Myeloma cells exposed to imexon showed classic morphologic features of apoptosis upon electron microscopy, and increased levels of phosphatidylserine exposure, detected as Annexin-V binding, on the cell surface. To prevent depletion of thiols, 8226 myeloma cells exposed to imexon were treated with N-acetylcysteine (NAC). Simultaneous, as well as sequential, treatment with NAC before imexon exposure resulted in protection of myeloma cells against imexon-induced cytotoxicity. Conversely, the glutathione synthesis inhibitor buthionine sulfoximine increased imexon cytotoxicity. These data suggest that imexon perturbs cellular thiols and induces oxidative stress leading to apoptosis in human myeloma cells. (C) 2000 Elsevier Science Inc.",
keywords = "Apoptosis, Cyanoaziridine, Imexon, Multiple myeloma, Oxidative stress",
author = "Katerina Dvorakova and Payne, {Claire M.} and Tome, {Margaret E} and Briehl, {Margaret M} and Thomas McClure and Dorr, {Robert T}",
year = "2000",
month = "9",
day = "15",
doi = "10.1016/S0006-2952(00)00380-4",
language = "English (US)",
volume = "60",
pages = "749--758",
journal = "Biochemical Pharmacology",
issn = "0006-2952",
publisher = "Elsevier Inc.",
number = "6",

}

TY - JOUR

T1 - Induction of oxidative stress and apoptosis in myeloma cells by the aziridine-containing agent imexon

AU - Dvorakova, Katerina

AU - Payne, Claire M.

AU - Tome, Margaret E

AU - Briehl, Margaret M

AU - McClure, Thomas

AU - Dorr, Robert T

PY - 2000/9/15

Y1 - 2000/9/15

N2 - Imexon is an iminopyrrolidone derivative that has selective antitumor activity in multiple myeloma. The exact mechanism of imexon action is unknown. In human 8226 myeloma cells, the cytotoxicity of imexon was schedule-dependent, and long exposures (≥48 hr) to low concentrations of imexon were most effective at inducing cytotoxicity. Our data suggest that imexon does not affect DNA, but it can alkylate thiols by binding to the sulfhydryl group. We have also demonstrated by HPLC studies that in human 8226 myeloma cells, imexon depletes cellular stores of cysteine and glutathione. Oxidative stress in 8226 cells exposed to imexon was detected by immunohistochemical staining with a monoclonal antibody to 8-hydroxydeoxyguanosine (8-OHdG), followed by confocal microscopy. These images showed increased levels of 8-OHdG in the cytoplasm of cells treated with different concentrations of imexon at 8, 16, and 48 hr. Interestingly, 8-OHdG staining was not observed in the nuclei of imexon-treated cells, in contrast to the diffuse staining seen with t-butyl hydroperoxide. Myeloma cells exposed to imexon showed classic morphologic features of apoptosis upon electron microscopy, and increased levels of phosphatidylserine exposure, detected as Annexin-V binding, on the cell surface. To prevent depletion of thiols, 8226 myeloma cells exposed to imexon were treated with N-acetylcysteine (NAC). Simultaneous, as well as sequential, treatment with NAC before imexon exposure resulted in protection of myeloma cells against imexon-induced cytotoxicity. Conversely, the glutathione synthesis inhibitor buthionine sulfoximine increased imexon cytotoxicity. These data suggest that imexon perturbs cellular thiols and induces oxidative stress leading to apoptosis in human myeloma cells. (C) 2000 Elsevier Science Inc.

AB - Imexon is an iminopyrrolidone derivative that has selective antitumor activity in multiple myeloma. The exact mechanism of imexon action is unknown. In human 8226 myeloma cells, the cytotoxicity of imexon was schedule-dependent, and long exposures (≥48 hr) to low concentrations of imexon were most effective at inducing cytotoxicity. Our data suggest that imexon does not affect DNA, but it can alkylate thiols by binding to the sulfhydryl group. We have also demonstrated by HPLC studies that in human 8226 myeloma cells, imexon depletes cellular stores of cysteine and glutathione. Oxidative stress in 8226 cells exposed to imexon was detected by immunohistochemical staining with a monoclonal antibody to 8-hydroxydeoxyguanosine (8-OHdG), followed by confocal microscopy. These images showed increased levels of 8-OHdG in the cytoplasm of cells treated with different concentrations of imexon at 8, 16, and 48 hr. Interestingly, 8-OHdG staining was not observed in the nuclei of imexon-treated cells, in contrast to the diffuse staining seen with t-butyl hydroperoxide. Myeloma cells exposed to imexon showed classic morphologic features of apoptosis upon electron microscopy, and increased levels of phosphatidylserine exposure, detected as Annexin-V binding, on the cell surface. To prevent depletion of thiols, 8226 myeloma cells exposed to imexon were treated with N-acetylcysteine (NAC). Simultaneous, as well as sequential, treatment with NAC before imexon exposure resulted in protection of myeloma cells against imexon-induced cytotoxicity. Conversely, the glutathione synthesis inhibitor buthionine sulfoximine increased imexon cytotoxicity. These data suggest that imexon perturbs cellular thiols and induces oxidative stress leading to apoptosis in human myeloma cells. (C) 2000 Elsevier Science Inc.

KW - Apoptosis

KW - Cyanoaziridine

KW - Imexon

KW - Multiple myeloma

KW - Oxidative stress

UR - http://www.scopus.com/inward/record.url?scp=0034666730&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0034666730&partnerID=8YFLogxK

U2 - 10.1016/S0006-2952(00)00380-4

DO - 10.1016/S0006-2952(00)00380-4

M3 - Article

C2 - 10930529

AN - SCOPUS:0034666730

VL - 60

SP - 749

EP - 758

JO - Biochemical Pharmacology

JF - Biochemical Pharmacology

SN - 0006-2952

IS - 6

ER -