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

作者：Caporali Simona; Levati Lauretta; Graziani Grazia; Muzi Alessia; Atzori Maria Grazia; Bonmassar Enzo; Palmieri Giuseppe; Ascierto Paolo A; D' Atri Stefania

来源：Journal of Translational Medicine, 2012, 10(1): 252.

DOI：10.1186/1479-5876-10-252

• Nuclear factor kB
• AKT
• Temozolomide
• NEMO binding domain peptide
• Cell proliferation
• Cell senescence

Background: Most DNA-damaging chemotherapeutic agents activate the transcription factor nuclear factor kB (NF-kB). However, NF-kB 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-kB, in a mismatch repair (MMR) system-dependent manner. Here we investigated whether NF-kB is activated by TMZ and whether AKT is involved in this molecular event. We also evaluated the functional consequence of inhibiting NF-kB on tumor cell response to TMZ. %26lt;br%26gt;Methods: AKT phosphorylation, NF-kB transcriptional activity, IkB-alpha degradation, NF-kB2/p52 generation, and RelA and NF-kB2/p52 nuclear translocation were investigated in TMZ-treated MMR-deficient (HCT116, 293TL alpha(-)) and/or MMR-proficient (HCT116/3-6, 293TL alpha(+), M10) cells. AKT involvement in TMZ-induced activation of NF-kB 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-kB on sensitivity to TMZ were investigated in HCT116/3-6 and M10 cells using the NF-kB inhibitor NEMO-binding domain (NBD) peptide or an anti-RelA siRNA. %26lt;br%26gt;Results: TMZ enhanced NF-kB transcriptional activity, activated AKT, induced IkB-alpha degradation and RelA nuclear translocation in HCT116/3-6 and M10 but not in HCT116 cells. In M10 cells, TMZ promoted NF-kB2/p52 generation and nuclear translocation and enhanced the secretion of IL-8 and MCP-1. TMZ induced RelA nuclear translocation also in 293TL alpha(+) but not in 293TL alpha(-) cells. AKT1 silencing inhibited TMZ-induced IkB-alpha degradation and NF-kB2/p52 generation. Up-regulation of NF-kB transcriptional activity and nuclear translocation of RelA and NF-kB2/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-kB activity, abrogated TMZ-induced up-regulation of NF-kB activity and increased sensitivity to TMZ. In HCT116/3-6 cells, the combined treatment with NBD peptide and TMZ produced additive growth inhibitory effects. %26lt;br%26gt;Conclusion: NF-kB 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-kB inhibitors.

• 出版日期2012-12-21