| Objective: Two NSCLC cell lines with different expression of the epidermal growth factor receptor (EGFR) treated by combined gefitinib and irradiation, observe the difference between treated and control group of radiosensitivity, capacity for repairing DNA double strand breaks(DSB) and radiation-induced EGFR transport into the nucleus.Methods: A549 and H1299 were treated with 10μmol/L gefitibib for 24 h before irradiation and then tested for clonogenic survival, capacity for repairing DNA double strand breaks (DSB) with immunofluorescent staining forγ-H2AX and EGFR expression in kytoplasm and nucleus with western blot analysis.Results: 1) The treated group SF2(0.355)was lower than the control(0.4443)in A549; there was no obvious difference between the tow groups in H1975 (0.3094 vs.0.3207);2) Gefitinib increased the average numbers ofγ-H2AX foci after irradiation in A549 ( T30min=22.33±2.30,t30min=14.18±2.61;T45min=15.95±2.40,t45min=11.40±1.75;T60min=11.47±1.19,t60min=4.40±0.58; P <0.05);but have no influence on the amount in H1975(T30min=22.07±0.56,t30min=21.59±1.52;T45min=15.97±0.90,t45min=15.63±0.93;T60min=11.39±0.39,t60min=10.83±1.29; P >0.05);3) Gefitinib had radiosensitizing function on A549 with inhibiting EGFR into the nucleus, the increased EGFR in kytoplasm ( T0min=18.1±0.306,t0min=12.3±0.557;T15min=18.2±0.306,t15min=11.1±0.379;T30min=16.2±0.551,t30min=7.37±0.451;T60min=15.5±0.265,t60min=4.53±0.379; P <0.05)and decreased in nucleus ( T15min=0.51±0.050,t15min=4.93±0.321;T30min=1.03±0.115,t30min=5.20±0.361;T60min=0.81±0.025,t60min=5.70±0.458; P <0.05);not find the change in H1975(T0min=1.80±0.042,t0min=1.73±0.07;T15min=1.76±0.043,t15min=1.51±0.040;T30min=1.68±0.040,t30min=1.75±0.051;T60min=1.70±0.021,t60min=1.65±0.036; P >0.05).Conclusion: Gefitinib enhances the radioresponse of A549 cells proberbly by suppressing EGFR transport into the nucleus; but have no influnce on H1975, with the relation of EGFR only staying in kytoplasm... |
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