| Objective to explore the radioresistance difference between SHG-44and U251cell line,investigate the correlation among radioresistance, APEX1mRNA expression,DNA-ploidy and cell cycle distribution.Methods colony formation assay was adopted to determined the radioresistance difference, The radiation dose-survival curve was fitted by multiple-hit single-target model formula S=1-(1-e-D/D0)N,APEX1mRNA expression was determined by means of RT-PCR, DNA-ploidy and cell cycle distribution ware investigated by means of flow cytometry, their correlation were analysised by linear correlation.Results compared with U251(pathological grade:WHOⅣ),SHG-44(pathological grade:WHO Ⅱ-Ⅲ) was more radioresistant,SF2(U25i)=0.58±0.02, SF2(SHG-44)=0.70±0.15, t=3.19, p<0.05,the radiation dose-survival curve fitted by multiple-hit single-target model formula shows that SF2(U251)=0.59, Do(U251)=2.30, Dq(U251)=1.11,N(U251)=1.62; SF2(SHG-44)=0.70,Do(SHG-44)5.16, Dq(SHG-44)=2.44, N(SHG-44)=1.07, Radiobiological parameters indicated that SHG-44cells have less repair capacity of DNA damage. Further studies show APEX1mRNA expression of SHG-44cells was lower(1.17±0.04VS0.70±0.18, t=19.92, p<0.05),U251cell was diploidy(DI=1.009±0.006),SHG-44cell was aneuploidy(DI=1.540±0.021), p<0.001.compared with U251,G1phase proportion of SHG-44cell was higher(60.13±3.26VS51.72±5.14, t=2.51, p<0.05),S phase proportion was lower(18.57±0.64VS28.80±2.96, t=5.09, p<0.05),and there is no significant difference in G2phase between U251and SHG-44(17.63+3.91VS21.78+4.81, t=1.25, p>0.05),G1phase arrest was correlated to radioresistance, r=0.735, p<0.05.Conclusion Radioresistance may be negatively correlated with pathological grade in glioma,there may be different radioresistance mechanisms in different styles of gliomas,APEX1is not correlated with radioresistance in glioma SHG-44, aneuploidy glioma cells may be more radioresistance, G1phase arrest may be correlated with radioresistance in glioma SHG-44. |
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