Abstract
The recent progress in chemotherapy for malignant gliomas is attributable to the introduction of the DNA-methylating agent temozolomide (TMZ); however, drug resistance remains a major issue. Previous studies have shown that TMZ induces prolonged arrest of human glioma cells in the G2/M phase of the cell cycle followed by a senescence-like phenomenon or mitotic catastrophe. These findings suggest that the G2 checkpoint is linked to DNA repair mechanisms. We investigated the effect of a cyclin-dependent kinase (Cdk) inhibitor flavopiridol (FP) that inhibits the action of Cdc2, a key protein in the G2 checkpoint pathway, on TMZ-treated glioma cells. Colony formation efficiency revealed that FP potentiated the cytotoxicity of TMZ in glioma cells in a p53-independent manner. This effect was clearly associated with the suppression of key proteins at the G2-M transition, accumulation of the cells exclusively at the G2 phase, and increase in a double-stranded DNA break marker (seen on performing immunoblotting). TMZ-resistant clones showed activation of the G2 checkpoint in response to TMZ, while FP treatment resensitized these clones to TMZ. FP also enhanced the cytotoxicity of TMZ in U87MG-AktER cells. Moreover, administration of TMZ and/or FP to nude mice with xenografted U87MG cells revealed that FP sensitized xenografted U87MG cells to TMZ in these mice. Our findings suggest that TMZ resistance could be promoted by enhanced DNA repair activity in the G2-M transition and that a Cdk inhibitor could suppress this activity, leading to potentiation of TMZ action on glioma cells.
| Original language | English |
|---|---|
| Pages (from-to) | 169-178 |
| Number of pages | 10 |
| Journal | Journal of Neuro-Oncology |
| Volume | 115 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - 14-08-2013 |
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All Science Journal Classification (ASJC) codes
- Oncology
- Neurology
- Clinical Neurology
- Cancer Research
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The Cdk inhibitor flavopiridol enhances temozolomide-induced cytotoxicity in human glioma cells. / Hayashi, Takuro; Adachi, Kazuhide; Ohba, Shigeo; Hirose, Yuichi.
In: Journal of Neuro-Oncology, Vol. 115, No. 2, 14.08.2013, p. 169-178.Research output: Contribution to journal › Article
TY - JOUR
T1 - The Cdk inhibitor flavopiridol enhances temozolomide-induced cytotoxicity in human glioma cells
AU - Hayashi, Takuro
AU - Adachi, Kazuhide
AU - Ohba, Shigeo
AU - Hirose, Yuichi
PY - 2013/8/14
Y1 - 2013/8/14
N2 - The recent progress in chemotherapy for malignant gliomas is attributable to the introduction of the DNA-methylating agent temozolomide (TMZ); however, drug resistance remains a major issue. Previous studies have shown that TMZ induces prolonged arrest of human glioma cells in the G2/M phase of the cell cycle followed by a senescence-like phenomenon or mitotic catastrophe. These findings suggest that the G2 checkpoint is linked to DNA repair mechanisms. We investigated the effect of a cyclin-dependent kinase (Cdk) inhibitor flavopiridol (FP) that inhibits the action of Cdc2, a key protein in the G2 checkpoint pathway, on TMZ-treated glioma cells. Colony formation efficiency revealed that FP potentiated the cytotoxicity of TMZ in glioma cells in a p53-independent manner. This effect was clearly associated with the suppression of key proteins at the G2-M transition, accumulation of the cells exclusively at the G2 phase, and increase in a double-stranded DNA break marker (seen on performing immunoblotting). TMZ-resistant clones showed activation of the G2 checkpoint in response to TMZ, while FP treatment resensitized these clones to TMZ. FP also enhanced the cytotoxicity of TMZ in U87MG-AktER cells. Moreover, administration of TMZ and/or FP to nude mice with xenografted U87MG cells revealed that FP sensitized xenografted U87MG cells to TMZ in these mice. Our findings suggest that TMZ resistance could be promoted by enhanced DNA repair activity in the G2-M transition and that a Cdk inhibitor could suppress this activity, leading to potentiation of TMZ action on glioma cells.
AB - The recent progress in chemotherapy for malignant gliomas is attributable to the introduction of the DNA-methylating agent temozolomide (TMZ); however, drug resistance remains a major issue. Previous studies have shown that TMZ induces prolonged arrest of human glioma cells in the G2/M phase of the cell cycle followed by a senescence-like phenomenon or mitotic catastrophe. These findings suggest that the G2 checkpoint is linked to DNA repair mechanisms. We investigated the effect of a cyclin-dependent kinase (Cdk) inhibitor flavopiridol (FP) that inhibits the action of Cdc2, a key protein in the G2 checkpoint pathway, on TMZ-treated glioma cells. Colony formation efficiency revealed that FP potentiated the cytotoxicity of TMZ in glioma cells in a p53-independent manner. This effect was clearly associated with the suppression of key proteins at the G2-M transition, accumulation of the cells exclusively at the G2 phase, and increase in a double-stranded DNA break marker (seen on performing immunoblotting). TMZ-resistant clones showed activation of the G2 checkpoint in response to TMZ, while FP treatment resensitized these clones to TMZ. FP also enhanced the cytotoxicity of TMZ in U87MG-AktER cells. Moreover, administration of TMZ and/or FP to nude mice with xenografted U87MG cells revealed that FP sensitized xenografted U87MG cells to TMZ in these mice. Our findings suggest that TMZ resistance could be promoted by enhanced DNA repair activity in the G2-M transition and that a Cdk inhibitor could suppress this activity, leading to potentiation of TMZ action on glioma cells.
UR - http://www.scopus.com/inward/record.url?scp=84886588314&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84886588314&partnerID=8YFLogxK
U2 - 10.1007/s11060-013-1220-5
DO - 10.1007/s11060-013-1220-5
M3 - Article
C2 - 23943501
AN - SCOPUS:84886588314
VL - 115
SP - 169
EP - 178
JO - Journal of Neuro-Oncology
JF - Journal of Neuro-Oncology
SN - 0167-594X
IS - 2
ER -