Radiosensitivity And Growth Characteristics Of Filial Generation From Irradiated Human Glioma Cell Line SHG-44

Part IRadiosensitivity of filial generation from irradiated human glioma cellline SHG-44Objective: To investigate the radiosensitivity and growth features of the progeny of irradiated human glioma cell line SHG-44.Methods: The SHG-44 cells were irradiated with 6MV X ray and the progeny of the cells were cultured. The population doubling time(PDT) was detected pre- and post- irradiation. The radiosensitivity of the progeny of irradiated human glioma cell line SHG-44 was measured by clone forming assay. The cell cycle distribution was analysed by Flow Cytometry(FCM).Results: The PDT of SHG-44 cells before irradiation was 22.78+2.61h.The PDT of irradiated SHG-44 cells at dose of 10Gy were 30.46+2.73h(P<0.05). The SF₂ of SHG-44 cell was 70.8%. The SF₂ of irradiated SHG-44cell was 80.6% (P<0.05) . SHG-44 cells showed significant G₂/M phasedecrease and S phase arrest after irradiation .Conclusion: In the present study, growth delay and declined radiosensitivity are confirmed in the progeny of irradiated SHG-44 cells.Part IIThe effects of acetaminophen(ACE) combinated with radiation on the radiosensitivity of filial generation from irradiated human glioma cell lineSHG-44Objective: To study the effects of acetaminophen(ACE) combinated with radiation on the cell proliferation, cycle distribution and apoptosis of filial generation from irradiated human glioma cell line SHG-44 in vitro and to investigate if ACE may prove to be a useful therapeutic agent and radiosensitization in the treatment of recurrent human glioma.Methods: The SHG-44 cells were irradiated with 6MV X ray and the progeny of the cells were cultured. The culture of the progeny of irradiated human glioma cell line SHG-44 was treated with ACE to do the radiosensitive experiment. ACE's radiosensitivity was measured by clone forming assay. The cell cycle distribution was analyzed by Flow Cytometry(FCM).Results: The culture of the progeny of irradiated human glioma cell line SHG-44 was treated with ACE to do the radiosesitive experiment. The results of clone conforming assay discovered that, ACE plus radiation group(D+R)'s parameters of Do, Dq, N were smaller than radiation group(R)'s, The Do of R group was 1.46-fold more than D+R group. Cell cycle analysis showed that in control group(C), most cells were in the GrS phase, some cells were in the G2 phase. The percentages of the G2/M phase cells in R and D+R groups were significantly more than C group after treatment for 12h(P<0.01), but the percentages between R group and D+R group had no different(P>0.05). After treatment for 24h,the percentages of the G2/M phase cells in R group decreased rapidly and having no different with C group(P>0.05),while the percentage in D+R group maintained in high level and having different with other groups(p<0.01).There were no differences between every two groupsafter treatment for 48h(p>0.05).Conclusion: 1. Subtoxic dose of ACE increased the sensitivity of the progeny of irradiated human glioma cell line SHG-44 in culture to ionizing radiation. The mechanism may be block the SHG-44 cells in the G2/M phase of the cell cycle and induce cells apoptosis. 2. Taken together, these results suggest that acetaminophen may prove to be a useful therapeutic agent and radiosensitization in the treatment of recrudescent human malignant glioma.