Abstract
PURPOSE: To investigate the radiosensitizing potential of temozolomide (TMZ) for human glioblastoma multiforme (GBM) cell lines using single-dose and fractionated gamma-irradiation.
METHODS AND MATERIALS: Three genetically characterized human GBM cell lines (AMC-3046, VU-109, and VU-122) were exposed to various single (0-6 Gy) and daily fractionated doses (2 Gy per fraction) of gamma-irradiation. Repeated TMZ doses were given before and concurrent with irradiation treatment. Immediately plated clonogenic cell-survival curves were determined for both the single-dose and the fractionated irradiation experiments. To establish the net effect of clonogenic cell survival and cell proliferation, growth curves were determined, expressed as the number of surviving cells.
RESULTS: All three cell lines showed MGMT promoter methylation, lacked MGMT protein expression, and were sensitive to TMZ. The isotoxic TMZ concentrations used were in a clinically feasible range of 10 micromol/L (AMC-3046), 3 micromol/L (VU-109), and 2.5 micromol/L (VU-122). Temozolomide was able to radiosensitize two cell lines (AMC 3046 and VU-122) using single-dose irradiation. A reduction in the number of surviving cells after treatment with the combination of TMZ and fractionated irradiation was seen in all three cell lines, but only AMC 3046 showed a radiosensitizing effect.
CONCLUSIONS: This study on TMZ-sensitive GBM cell lines shows that TMZ can act as a radiosensitizer and is at least additive to gamma-irradiation. Enhancement of the radiation response by TMZ seems to be independent of the epigenetically silenced MGMT gene.
Original language | English |
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Pages (from-to) | 1246-53 |
Number of pages | 8 |
Journal | International journal of radiation oncology, biology, physics |
Volume | 69 |
Issue number | 4 |
DOIs | |
Publication status | Published - 15 Nov 2007 |
Keywords
- Brain Neoplasms/enzymology
- Cell Line, Tumor
- Cell Proliferation/drug effects
- Cell Survival/drug effects
- Combined Modality Therapy/methods
- DNA Methylation
- Dacarbazine/analogs & derivatives
- Dose Fractionation
- Genes, Tumor Suppressor
- Glioblastoma/enzymology
- Humans
- Neoplasm Proteins/metabolism
- O(6)-Methylguanine-DNA Methyltransferase/metabolism
- Radiation Tolerance/drug effects
- Radiation-Sensitizing Agents/therapeutic use
- Xenograft Model Antitumor Assays/methods