title: Cell death induced by high-linear-energy transfer carbon beams in human glioblastoma cell lines.
abstract: The cytotoxic effect of high-linear-energy transfer (LET) carbon beams on two human glioblastoma cell lines (A172 and TK1) was analyzed, especially concerning cell death, including apoptosis. Gamma-ray radiation was used for comparison. The results of standard colony formation assay showed that the survival fraction of each cell line decreased in an LET-dependent manner. The results of other direct cytotoxic assays, dye exclusion test, and lactate dehydrogenase (LDH) release assay, also displayed a similar relationship between the cytotoxic effect of carbon beams and LET. The maximum values of the cell death index (CDI) were 50.2% in A172 and 37.5% in TK1, both obtained on day 7 after exposure to carbon beams of 80 keV/microm. Apoptosis was observed only on days 4 and 7 after carbon beam irradiation, with maximum values of 7% in A172 and 4.5% in TK1, and the induction of apoptosis after high-LET radiation could be p53-independent. This indicated that a combination of multiple assays to detect cell death was important in evaluating the radiosensitivity of tumor cells, because this approach could more precisely reflect the clinical effectiveness of radiotherapy.
mesh_terms: D017209:Apoptosis; D001932:Brain Neoplasms / Q000201:enzymology / Q000473:pathology* / Q000532:radiotherapy*; D002244:Carbon; D016923:Cell Death; D004307:Dose-Response Relationship, Radiation; D004923:Erythrosine / Q000493:pharmacokinetics; D005720:Gamma Rays / Q000627:therapeutic use; D005909:Glioblastoma / Q000201:enzymology / Q000473:pathology* / Q000532:radiotherapy*; D063193:Heavy Ion Radiotherapy; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D010315:Particle Accelerators; D013997:Time Factors; D014407:Tumor Cells, Cultured; D014410:Tumor Stem Cell Assay