Single-fraction gamma[-60]Co radiation induces apoptosis in cultured rat C6 cells

Radiotherapy is frequently applied in the treatment of malignant gliomas, but it is unclear if radiotherapy exerts its effects via induction of apoptosis. The present study was designed to determine whether a single-fraction gamma-60Co radiation can induce apoptosis. In vitro cytological controlled study performed at a military medical university from October 2006 to June 2008. C6 cells were treated with a single fraction of gamma-60Co radiation at various doses [0, 4, 16, and 64 Gy]. The 3-[4,5]-dimethylthiazol-2]-2,5-diphenyl tetrazolium bromide [MTT] assay, apoptosis assays using Annexin V-fluorescein isothiocyanate /propidium iodide or Hoechst 33258 staining, and the cell cycle assay were performed, and the expression of p53 and p21 proteins was evaluated. The C6 cell numbers in the 16 Gy and 64 Gy groups were much lower than in the control group at 48, 96, and 144 hours after irradiation. The irradiated cells underwent apoptosis in a dose-dependent manner. Irradiation also impacted cell cycle progression, arresting cells in the G1 phase. The p53 protein expression was shown in both the nucleus and the cytoplasm of irradiated cells, whereas p53 was only expressed in the nucleus of control [untreated] cells. The p21 protein was expressed in irradiated cells but not in control cells. Single-fraction gamma-60Co radiation inhibited C6 cell growth by inducing apoptosis and G1 arrest, which correlated with the up-regulation of the p53-p21 pathway. The extent of apoptosis and G1 arrest was positively correlated with the dose of radiation. Better understanding of apoptosis induced by radiation therapy will help design optimal dosing schedules for radiation therapy, especially in combination with chemotherapy

Boron neutron capture inducing apoptosis in C6 glioma cells / 中华放射肿瘤学杂志

Objective To investigate the effect and mechanism of boron neutron capture therapy(BNCT) in C6 glioma cell line.Methods C6 cells in exponential phase were divided into 6 groups: untreated control,(~(60)Co?)(4 Gy),~(60)Co? 8 Gy,nuclear reactor exposure without boronophenylalanine(BPA) 3 Gy,BNCT(4 Gy) and BNCT 8 Gy.Cellular morphological change was observed by an inverted microscope,light microscope,fluorescence microscope and electronic microscope.Flow cytometry was used to determine the percentage of apoptosis,necrosis and normal cells 48h after irradiation.Colony forming assay was used to calculate cell surviving fraction.Results Typical morphological changes of apoptosis were observed early after irradiation in BNCT group,with a significant increase in apoptotic rates was observed 48 h after irradiation with 63.2% and 88.3% for BNCT(4 Gy) and 8 Gy group,respectively(P

In vitro study of incorporation of p-boronophenylalanine (BPA) by glioma cells and its relationship with cell cycle / 解放军医学杂志

Objective To evaluate the incorporation of BPA, which was synthesized by ourselves, by two different glioma cell lines, and to observe its relationship with the time of cultivation and cell cycle. Methods Two glioma cell lines of C6 and SHG-44 were studied and the primarily cultured rat astrocytes were used as control. The growth curves of the two glioma cell lines and rat astrocytes were plotted, and their doubling time was identified respectively from the curves. All three kinds of cells were incubated in a culture medium, in which 10 B concentration was 50?g/ml for 4h, 8h, 16h, 20h or 24h. Boron concentration in the cells was measured by induced couple plasma atomic emission spectroscopy (ICP-AES) after respective culture period. After 24h of incubation, the cells in the G 0 /G 1 phase and those in the G 2 /M phase were isolated by flow cytometry, and boron concentration in each fraction was obtained by ICP-AES. Results The doubling time was 18.5h for both C6 and SHG-44 cells, but 28h for the astrocytes. The boron concentration in glioma cells was constantly higher than that in astrocytes throughout the experiment(P