The double-stranded RNA-activated protein kinase mediates radiation resistance in mouse embryo fibroblasts through nuclear factor κB and Akt activation

Urs Von Holzen, Abujiang Pataer, Uma Raju, Dora Bocangel, Stephan A. Vorburger, Yanna Liu, Xiaolin Lu, Jack A. Roth, Bharat B. Aggarwal, Glen N Barber, Khandan Keyomarsi, Kelly K. Hunt, Stephen G. Swisher

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Purpose: Activation of the double-stranded RNA-activated protein kinase (PKR) leads to the induction of various pathways including the down-regulation of translation through phosphorylation of the eukaryotic translation initiation factor 2α (eIF-2α). There have been no reports to date about the role of PKR in radiation sensitivity. Experimental Design: A clonogenic survival assay was used to investigate the sensitivity of PKR mouse embryo fibroblasts (MEF) to radiation therapy. 2-Aminopurine (2-AP), a chemical inhibitor of PKR, was used to inhibit PKR activation. Nuclear factor-κB (NF-κB) activation was assessed by electrophoretic mobility shift assay (EMSA). Expression of PKR and downstream targets was examined by Western blot analysis and immunofluorescence. Results: Ionizing radiation leads to dose- and time-dependent increases in PKR expression and function that contributes to increased cellular radiation resistance as shown by clonogenic survival and terminal nucleotidyl transferase-mediated nick end labeling (TUNEL) apoptosis assays. Specific inhibition of PKR with the chemical inhibitor 2-AP restores radiation sensitivity. Plasmid transfection of the PKR wild-type (wt) gene into PKR-/- MEFs leads to increased radiation resistance. The protective effect of PKR to radiation may be mediated in part through NF-κB and Akt because both NF-κB and Akt are activated after ionizing radiation in PKR+/+ but not PKR-/- cells. Conclusions: We suggest a novel role for PKR as a mediator of radiation resistance modulated in part through the protective effects of NF-κB and Akt activation. The modification of PKR activity may be a novel strategy in the future to overcome radiation resistance.

Original languageEnglish
Pages (from-to)6032-6039
Number of pages8
JournalClinical Cancer Research
Volume13
Issue number20
DOIs
StatePublished - Oct 15 2007

Fingerprint

eIF-2 Kinase
Double-Stranded RNA
Embryonic Structures
Fibroblasts
Radiation
2-Aminopurine
Radiation Tolerance
Ionizing Radiation
Eukaryotic Initiation Factor-2
Eukaryotic Initiation Factors
In Situ Nick-End Labeling
Electrophoretic Mobility Shift Assay
Transferases
Fluorescent Antibody Technique
Transfection
Plasmids
Research Design
Radiotherapy
Down-Regulation
Western Blotting

ASJC Scopus subject areas

  • Cancer Research
  • Oncology

Cite this

The double-stranded RNA-activated protein kinase mediates radiation resistance in mouse embryo fibroblasts through nuclear factor κB and Akt activation. / Von Holzen, Urs; Pataer, Abujiang; Raju, Uma; Bocangel, Dora; Vorburger, Stephan A.; Liu, Yanna; Lu, Xiaolin; Roth, Jack A.; Aggarwal, Bharat B.; Barber, Glen N; Keyomarsi, Khandan; Hunt, Kelly K.; Swisher, Stephen G.

In: Clinical Cancer Research, Vol. 13, No. 20, 15.10.2007, p. 6032-6039.

Research output: Contribution to journalArticle

Von Holzen, U, Pataer, A, Raju, U, Bocangel, D, Vorburger, SA, Liu, Y, Lu, X, Roth, JA, Aggarwal, BB, Barber, GN, Keyomarsi, K, Hunt, KK & Swisher, SG 2007, 'The double-stranded RNA-activated protein kinase mediates radiation resistance in mouse embryo fibroblasts through nuclear factor κB and Akt activation', Clinical Cancer Research, vol. 13, no. 20, pp. 6032-6039. https://doi.org/10.1158/1078-0432.CCR-06-2932
Von Holzen, Urs ; Pataer, Abujiang ; Raju, Uma ; Bocangel, Dora ; Vorburger, Stephan A. ; Liu, Yanna ; Lu, Xiaolin ; Roth, Jack A. ; Aggarwal, Bharat B. ; Barber, Glen N ; Keyomarsi, Khandan ; Hunt, Kelly K. ; Swisher, Stephen G. / The double-stranded RNA-activated protein kinase mediates radiation resistance in mouse embryo fibroblasts through nuclear factor κB and Akt activation. In: Clinical Cancer Research. 2007 ; Vol. 13, No. 20. pp. 6032-6039.
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T1 - The double-stranded RNA-activated protein kinase mediates radiation resistance in mouse embryo fibroblasts through nuclear factor κB and Akt activation

AU - Von Holzen, Urs

AU - Pataer, Abujiang

AU - Raju, Uma

AU - Bocangel, Dora

AU - Vorburger, Stephan A.

AU - Liu, Yanna

AU - Lu, Xiaolin

AU - Roth, Jack A.

AU - Aggarwal, Bharat B.

AU - Barber, Glen N

AU - Keyomarsi, Khandan

AU - Hunt, Kelly K.

AU - Swisher, Stephen G.

PY - 2007/10/15

Y1 - 2007/10/15

N2 - Purpose: Activation of the double-stranded RNA-activated protein kinase (PKR) leads to the induction of various pathways including the down-regulation of translation through phosphorylation of the eukaryotic translation initiation factor 2α (eIF-2α). There have been no reports to date about the role of PKR in radiation sensitivity. Experimental Design: A clonogenic survival assay was used to investigate the sensitivity of PKR mouse embryo fibroblasts (MEF) to radiation therapy. 2-Aminopurine (2-AP), a chemical inhibitor of PKR, was used to inhibit PKR activation. Nuclear factor-κB (NF-κB) activation was assessed by electrophoretic mobility shift assay (EMSA). Expression of PKR and downstream targets was examined by Western blot analysis and immunofluorescence. Results: Ionizing radiation leads to dose- and time-dependent increases in PKR expression and function that contributes to increased cellular radiation resistance as shown by clonogenic survival and terminal nucleotidyl transferase-mediated nick end labeling (TUNEL) apoptosis assays. Specific inhibition of PKR with the chemical inhibitor 2-AP restores radiation sensitivity. Plasmid transfection of the PKR wild-type (wt) gene into PKR-/- MEFs leads to increased radiation resistance. The protective effect of PKR to radiation may be mediated in part through NF-κB and Akt because both NF-κB and Akt are activated after ionizing radiation in PKR+/+ but not PKR-/- cells. Conclusions: We suggest a novel role for PKR as a mediator of radiation resistance modulated in part through the protective effects of NF-κB and Akt activation. The modification of PKR activity may be a novel strategy in the future to overcome radiation resistance.

AB - Purpose: Activation of the double-stranded RNA-activated protein kinase (PKR) leads to the induction of various pathways including the down-regulation of translation through phosphorylation of the eukaryotic translation initiation factor 2α (eIF-2α). There have been no reports to date about the role of PKR in radiation sensitivity. Experimental Design: A clonogenic survival assay was used to investigate the sensitivity of PKR mouse embryo fibroblasts (MEF) to radiation therapy. 2-Aminopurine (2-AP), a chemical inhibitor of PKR, was used to inhibit PKR activation. Nuclear factor-κB (NF-κB) activation was assessed by electrophoretic mobility shift assay (EMSA). Expression of PKR and downstream targets was examined by Western blot analysis and immunofluorescence. Results: Ionizing radiation leads to dose- and time-dependent increases in PKR expression and function that contributes to increased cellular radiation resistance as shown by clonogenic survival and terminal nucleotidyl transferase-mediated nick end labeling (TUNEL) apoptosis assays. Specific inhibition of PKR with the chemical inhibitor 2-AP restores radiation sensitivity. Plasmid transfection of the PKR wild-type (wt) gene into PKR-/- MEFs leads to increased radiation resistance. The protective effect of PKR to radiation may be mediated in part through NF-κB and Akt because both NF-κB and Akt are activated after ionizing radiation in PKR+/+ but not PKR-/- cells. Conclusions: We suggest a novel role for PKR as a mediator of radiation resistance modulated in part through the protective effects of NF-κB and Akt activation. The modification of PKR activity may be a novel strategy in the future to overcome radiation resistance.

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