Increased radiosensitivity and radiothermosensitivity of human pancreatic MIA PaCa-2 and U251 glioblastoma cell lines treated with the novel Hsp90 inhibitor NVP-HSP990

Radiat Oncol. 2013 Feb 28;8:42. doi: 10.1186/1748-717X-8-42.


Background and purpose: Heat shock Protein 90 (Hsp90) is a molecular chaperone that folds, stabilizes, and functionally regulates many cellular proteins involved in oncogenic signaling and in the regulation of radiosensitivity. It is upregulated in response to stress such a heat. Hyperthermia is a potent radiosensitizer, but induction of Hsp90 may potentially limit its efficacy. Our aim was to investigate whether the new Hsp90 inhibitor NVP-HSP990 increases radiosensitivity, thermosensitivity and radiothermosensitivity of human tumor cell lines.

Material and methods: U251 glioblastoma and MIA PaCa-2 pancreatic carcinoma cells were used. To determine clonogenic survival, colony forming assays were performed. Cell viability and proliferation were assesed by Trypan blue staining. Cell cycle and apoptosis analyses were performed by flow cytometry. DAPI staining was used to detect mitotic catastrophe.

Results: NVP-HSP990 increased the thermosensitivity, radiosensitivity and radio-thermosensitivity of both cell lines in clonogenic assays. 72 hours after irradiation with 4 Gy, a significant reduction in cell number associated with considerable G2/M acumulation and mitotic catastrophe as well as cell death by apoptosis/necrosis was observed.

Conclusions: Treatment with NVP-HSP990 strongly sensitized U251 and MIA PaCa-2 cells to hyperthermia and ionizing radiation or combination thereof through augmentation of G2/M arrest, mitotic catastrophe and associated apoptosis.

MeSH terms

  • Antineoplastic Agents / pharmacology
  • Apoptosis / drug effects*
  • Brain Neoplasms / metabolism
  • Brain Neoplasms / pathology*
  • Brain Neoplasms / therapy
  • Cell Cycle / drug effects
  • Cell Proliferation / drug effects
  • Colony-Forming Units Assay
  • Combined Modality Therapy
  • Flow Cytometry
  • Gamma Rays
  • Glioblastoma / metabolism
  • Glioblastoma / pathology*
  • Glioblastoma / therapy
  • HSP90 Heat-Shock Proteins / antagonists & inhibitors*
  • Humans
  • Hyperthermia, Induced*
  • Pyridones / pharmacology*
  • Pyrimidines / pharmacology*
  • Radiation Tolerance / drug effects*
  • Radiation-Sensitizing Agents / pharmacology
  • Tumor Cells, Cultured


  • 2-amino-7-(4-fluoro-2-(6-methoxypyridin-2-yl)phenyl)-4-methyl-7,8-dihydropyrido(4,3-d)pyrimidin-5(6H)-one
  • Antineoplastic Agents
  • HSP90 Heat-Shock Proteins
  • Pyridones
  • Pyrimidines
  • Radiation-Sensitizing Agents