Abrogation of the Chk1-mediated G2 checkpoint pathway potentiates temozolomide-induced toxicity in a p53-independent manner in human glioblastoma cells

Yuichi Hirose, M. S. Berger, R. O. Pieper

Research output: Contribution to journalArticle

188 Citations (Scopus)

Abstract

Temozolomide (TMZ) produces O6-methylguanine in DNA, which in turn mispairs with thymine, triggering futile DNA mismatch repair (MMR) and ultimately cell death. We found previously that in p53-proficient human glioma cells, TMZ-induced futile DNA MMR resulted not in apoptosis but rather in prolonged, p53- and p21-associated G2-M arrest and senescence. Additionally, p53-deficient cells were relatively more TMZ resistant than p53-deficient glioma cells, which underwent only transient G2-M arrest before death by mitotic catastrophe. These results suggested that prolonged G2-M arrest might protect cells from TMZ-induced cytotoxicity. In the present study, we therefore focused on the mechanism by which TMZ induces G2-M arrest and on whether inhibition of such G2-M arrest might sensitize glioma cells to TMZ-induced toxicity. U87MG glioma cells treated with TMZ underwent G2-M arrest associated with Chk1 activation and phosphorylation of both cdc25C and cdc2. These TMZ-induced effects were inhibited by the Chk1 kinase inhibitor UCN-01. Although not in itself toxic, UCN-01 increased the cytotoxicity of TMZ 5-fold, primarily by inhibiting cellular senescence and increasing the percentage of cells bypassing G2-M arrest and undergoing mitotic catastrophe. In addition to enhancing TMZ-induced cytotoxicity in p53-proficient cells, UCN-01 also blocked TMZ-induced Chk1 activation and transient G2-M arrest in p53-deficient U87MG-E6 cells and similarly enhanced TMZ-induced mitotic catastrophe and cell death. Taken together, these results indicate that Chk1 links TMZ-induced MMR to G2-M arrest. Furthermore, inhibition of the cytoprotective G2 arrest pathway sensitizes cells to TMZ-induced cytotoxicity and may representa novel, mechanism-based means of increasing TMZ efficacy in both p53 wild-type and p53 mutant glioma cells.

Original languageEnglish
Pages (from-to)5843-5849
Number of pages7
JournalCancer Research
Volume61
Issue number15
Publication statusPublished - 01-08-2001
Externally publishedYes

Fingerprint

temozolomide
Glioblastoma
Glioma
DNA Mismatch Repair

All Science Journal Classification (ASJC) codes

  • Oncology
  • Cancer Research

Cite this

@article{c393b5c0031e4ac7a733bf012c493799,
title = "Abrogation of the Chk1-mediated G2 checkpoint pathway potentiates temozolomide-induced toxicity in a p53-independent manner in human glioblastoma cells",
abstract = "Temozolomide (TMZ) produces O6-methylguanine in DNA, which in turn mispairs with thymine, triggering futile DNA mismatch repair (MMR) and ultimately cell death. We found previously that in p53-proficient human glioma cells, TMZ-induced futile DNA MMR resulted not in apoptosis but rather in prolonged, p53- and p21-associated G2-M arrest and senescence. Additionally, p53-deficient cells were relatively more TMZ resistant than p53-deficient glioma cells, which underwent only transient G2-M arrest before death by mitotic catastrophe. These results suggested that prolonged G2-M arrest might protect cells from TMZ-induced cytotoxicity. In the present study, we therefore focused on the mechanism by which TMZ induces G2-M arrest and on whether inhibition of such G2-M arrest might sensitize glioma cells to TMZ-induced toxicity. U87MG glioma cells treated with TMZ underwent G2-M arrest associated with Chk1 activation and phosphorylation of both cdc25C and cdc2. These TMZ-induced effects were inhibited by the Chk1 kinase inhibitor UCN-01. Although not in itself toxic, UCN-01 increased the cytotoxicity of TMZ 5-fold, primarily by inhibiting cellular senescence and increasing the percentage of cells bypassing G2-M arrest and undergoing mitotic catastrophe. In addition to enhancing TMZ-induced cytotoxicity in p53-proficient cells, UCN-01 also blocked TMZ-induced Chk1 activation and transient G2-M arrest in p53-deficient U87MG-E6 cells and similarly enhanced TMZ-induced mitotic catastrophe and cell death. Taken together, these results indicate that Chk1 links TMZ-induced MMR to G2-M arrest. Furthermore, inhibition of the cytoprotective G2 arrest pathway sensitizes cells to TMZ-induced cytotoxicity and may representa novel, mechanism-based means of increasing TMZ efficacy in both p53 wild-type and p53 mutant glioma cells.",
author = "Yuichi Hirose and Berger, {M. S.} and Pieper, {R. O.}",
year = "2001",
month = "8",
day = "1",
language = "English",
volume = "61",
pages = "5843--5849",
journal = "Journal of Cancer Research",
issn = "0008-5472",
publisher = "American Association for Cancer Research Inc.",
number = "15",

}

Abrogation of the Chk1-mediated G2 checkpoint pathway potentiates temozolomide-induced toxicity in a p53-independent manner in human glioblastoma cells. / Hirose, Yuichi; Berger, M. S.; Pieper, R. O.

In: Cancer Research, Vol. 61, No. 15, 01.08.2001, p. 5843-5849.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Abrogation of the Chk1-mediated G2 checkpoint pathway potentiates temozolomide-induced toxicity in a p53-independent manner in human glioblastoma cells

AU - Hirose, Yuichi

AU - Berger, M. S.

AU - Pieper, R. O.

PY - 2001/8/1

Y1 - 2001/8/1

N2 - Temozolomide (TMZ) produces O6-methylguanine in DNA, which in turn mispairs with thymine, triggering futile DNA mismatch repair (MMR) and ultimately cell death. We found previously that in p53-proficient human glioma cells, TMZ-induced futile DNA MMR resulted not in apoptosis but rather in prolonged, p53- and p21-associated G2-M arrest and senescence. Additionally, p53-deficient cells were relatively more TMZ resistant than p53-deficient glioma cells, which underwent only transient G2-M arrest before death by mitotic catastrophe. These results suggested that prolonged G2-M arrest might protect cells from TMZ-induced cytotoxicity. In the present study, we therefore focused on the mechanism by which TMZ induces G2-M arrest and on whether inhibition of such G2-M arrest might sensitize glioma cells to TMZ-induced toxicity. U87MG glioma cells treated with TMZ underwent G2-M arrest associated with Chk1 activation and phosphorylation of both cdc25C and cdc2. These TMZ-induced effects were inhibited by the Chk1 kinase inhibitor UCN-01. Although not in itself toxic, UCN-01 increased the cytotoxicity of TMZ 5-fold, primarily by inhibiting cellular senescence and increasing the percentage of cells bypassing G2-M arrest and undergoing mitotic catastrophe. In addition to enhancing TMZ-induced cytotoxicity in p53-proficient cells, UCN-01 also blocked TMZ-induced Chk1 activation and transient G2-M arrest in p53-deficient U87MG-E6 cells and similarly enhanced TMZ-induced mitotic catastrophe and cell death. Taken together, these results indicate that Chk1 links TMZ-induced MMR to G2-M arrest. Furthermore, inhibition of the cytoprotective G2 arrest pathway sensitizes cells to TMZ-induced cytotoxicity and may representa novel, mechanism-based means of increasing TMZ efficacy in both p53 wild-type and p53 mutant glioma cells.

AB - Temozolomide (TMZ) produces O6-methylguanine in DNA, which in turn mispairs with thymine, triggering futile DNA mismatch repair (MMR) and ultimately cell death. We found previously that in p53-proficient human glioma cells, TMZ-induced futile DNA MMR resulted not in apoptosis but rather in prolonged, p53- and p21-associated G2-M arrest and senescence. Additionally, p53-deficient cells were relatively more TMZ resistant than p53-deficient glioma cells, which underwent only transient G2-M arrest before death by mitotic catastrophe. These results suggested that prolonged G2-M arrest might protect cells from TMZ-induced cytotoxicity. In the present study, we therefore focused on the mechanism by which TMZ induces G2-M arrest and on whether inhibition of such G2-M arrest might sensitize glioma cells to TMZ-induced toxicity. U87MG glioma cells treated with TMZ underwent G2-M arrest associated with Chk1 activation and phosphorylation of both cdc25C and cdc2. These TMZ-induced effects were inhibited by the Chk1 kinase inhibitor UCN-01. Although not in itself toxic, UCN-01 increased the cytotoxicity of TMZ 5-fold, primarily by inhibiting cellular senescence and increasing the percentage of cells bypassing G2-M arrest and undergoing mitotic catastrophe. In addition to enhancing TMZ-induced cytotoxicity in p53-proficient cells, UCN-01 also blocked TMZ-induced Chk1 activation and transient G2-M arrest in p53-deficient U87MG-E6 cells and similarly enhanced TMZ-induced mitotic catastrophe and cell death. Taken together, these results indicate that Chk1 links TMZ-induced MMR to G2-M arrest. Furthermore, inhibition of the cytoprotective G2 arrest pathway sensitizes cells to TMZ-induced cytotoxicity and may representa novel, mechanism-based means of increasing TMZ efficacy in both p53 wild-type and p53 mutant glioma cells.

UR - http://www.scopus.com/inward/record.url?scp=0035422203&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0035422203&partnerID=8YFLogxK

M3 - Article

VL - 61

SP - 5843

EP - 5849

JO - Journal of Cancer Research

JF - Journal of Cancer Research

SN - 0008-5472

IS - 15

ER -