Survivin inhibition and DNA double-strand break repair: A molecular mechanism to overcome radioresistance in glioblastoma

Sebastian Reichert, Claus Rödel, Johanna Mirsch, Patrick N. Harter, Maja T. Tomicic, Michel Mittelbronn, Bernd Kaina, Franz Rödel*

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

67 Citations (Scopus)

Abstract

Background and purpose: Gliomas display prime examples of ionizing radiation (IR) resistant tumors. The IAP Survivin is reported to be critically involved in radiation resistance by anti-apoptotic and by caspase-independent mechanisms. The present study aimed to elucidate an interrelationship between Survivin's cellular localization and DNA damage repair in glioma cells. Material and methods: Cellular distribution and nuclear complex formation were assayed by immunoblotting, immunofluorescence staining and co-immunoprecipitation of Survivin bound proteins in LN229 glioblastoma cells. Apoptosis induction, survival and DNA repair following IR were assayed by means of caspase3/7 activity, clonogenic assay, γ-H2AX/53BP1 foci formation, single cell gel electrophoresis assay, and DNA-PKcs kinase assay in the presence of Survivin siRNA or over expression of Survivin-GFP. Results: Following irradiation, we observed a nuclear accumulation and a direct interrelationship between Survivin, MDC1, γ-H2AX, 53BP1 and DNA-PKcs, which was confirmed by immunofluorescence co-localization. Survivin downregulation by siRNA resulted in an increased apoptotic fraction, decreased clonogenic survival and increased DNA-damage, as demonstrated by higher amount of DNA breaks and an increased amount of γ-H2AX/53BP1 foci post irradiation. Furthermore, we detected in Survivin-depleted LN229 cells a hampered S2056 (auto)phosphorylation and a significantly decreased DNA-PKcs kinase activity. Conclusion: Nuclear accumulation of Survivin and interaction with components of the DNA-double-strand break (DSB) repair machinery indicates Survivin to regulate DSB damage repair that leads to a significant improvement of survival of LN229 glioblastoma cells.

Original languageEnglish
Pages (from-to)51-58
Number of pages8
JournalRadiotherapy and Oncology
Volume101
Issue number1
DOIs
Publication statusPublished - Oct 2011
Externally publishedYes

Keywords

  • Apoptosis
  • DNA-PKcs
  • DNA-repair
  • Glioblastoma
  • Phospho-histone H2AX
  • Survivin

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