Dataset Information

NF-?B is activated in response to temozolomide in an AKT-dependent manner and confers protection against the growth suppressive effect of the drug.

ABSTRACT:

Background

Most DNA-damaging chemotherapeutic agents activate the transcription factor nuclear factor ?B (NF-?B). However, NF-?B activation can either protect from or contribute to the growth suppressive effects of the agent. We previously showed that the DNA-methylating drug temozolomide (TMZ) activates AKT, a positive modulator of NF-?B, in a mismatch repair (MMR) system-dependent manner. Here we investigated whether NF-?B is activated by TMZ and whether AKT is involved in this molecular event. We also evaluated the functional consequence of inhibiting NF-?B on tumor cell response to TMZ.

Methods

AKT phosphorylation, NF-?B transcriptional activity, I?B-? degradation, NF-?B2/p52 generation, and RelA and NF-?B2/p52 nuclear translocation were investigated in TMZ-treated MMR-deficient (HCT116, 293TL?-) and/or MMR-proficient (HCT116/3-6, 293TL?+, M10) cells. AKT involvement in TMZ-induced activation of NF-?B was addressed in HCT116/3-6 and M10 cells transiently transfected with AKT1-targeting siRNA or using the isogenic MMR-proficient cell lines pUSE2 and KD12, expressing wild type or kinase-dead mutant AKT1. The effects of inhibiting NF-?B on sensitivity to TMZ were investigated in HCT116/3-6 and M10 cells using the NF-?B inhibitor NEMO-binding domain (NBD) peptide or an anti-RelA siRNA.

Results

TMZ enhanced NF-?B transcriptional activity, activated AKT, induced I?B-? degradation and RelA nuclear translocation in HCT116/3-6 and M10 but not in HCT116 cells. In M10 cells, TMZ promoted NF-?B2/p52 generation and nuclear translocation and enhanced the secretion of IL-8 and MCP-1. TMZ induced RelA nuclear translocation also in 293TL?+ but not in 293TL?- cells. AKT1 silencing inhibited TMZ-induced I?B-? degradation and NF-?B2/p52 generation. Up-regulation of NF-?B transcriptional activity and nuclear translocation of RelA and NF-?B2/p52 in response to TMZ were impaired in KD12 cells. RelA silencing in HCT116/3-6 and M10 cells increased TMZ-induced growth suppression. In M10 cells NBD peptide reduced basal NF-?B activity, abrogated TMZ-induced up-regulation of NF-?B activity and increased sensitivity to TMZ. In HCT116/3-6 cells, the combined treatment with NBD peptide and TMZ produced additive growth inhibitory effects.

Conclusion

NF-?B is activated in response to TMZ in a MMR- and AKT-dependent manner and confers protection against drug-induced cell growth inhibition. Our findings suggest that a clinical benefit could be obtained by combining TMZ with NF-?B inhibitors.

SUBMITTER: Caporali S

PROVIDER: S-EPMC3551789 | biostudies-literature | 2012 Dec

REPOSITORIES: biostudies-literature

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Publications

NF-κB is activated in response to temozolomide in an AKT-dependent manner and confers protection against the growth suppressive effect of the drug.

Caporali Simona S Levati Lauretta L Graziani Grazia G Muzi Alessia A Atzori Maria Grazia MG Bonmassar Enzo E Palmieri Giuseppe G Ascierto Paolo A PA D'Atri Stefania S

Journal of translational medicine 20121221

<h4>Background</h4>Most DNA-damaging chemotherapeutic agents activate the transcription factor nuclear factor κB (NF-κB). However, NF-κB activation can either protect from or contribute to the growth suppressive effects of the agent. We previously showed that the DNA-methylating drug temozolomide (TMZ) activates AKT, a positive modulator of NF-κB, in a mismatch repair (MMR) system-dependent manner. Here we investigated whether NF-κB is activated by TMZ and whether AKT is involved in this molecul ...[more]

PMID: 23259744

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