The Research On Change Of Radiosensitivity And Reversal Of Drug Resistance Of Gefitinib-resistant Lung Adenocarcinoma Cell Caused By T790M Mutation

The first section:Research on the change of radiosensitivity of gefitinib-resistant lung adenocarcinoma cell caused by T790M mutationObjective:To explore the variation of radiosensitivity of the gefitinib-resistant lung adenocarcinoma PC-9/GR cell, and meanwhile to detect the expression level change of the radiosensitive molecule marker.Method:Liquid chip method was applied to detect the expression level of PTEN mRNA; western blot method was used to test the expression level of PTEN、p-mTOR、p-AKT proteins; colony formation assay was carried out in order to observe the survival situation of the cells that irradiated by X ray.Results:1. The relative content of PTEN mRNA is0.04663±0.00003in PC-9cell and0.07733±0.00002in PC-9/GR cell, respectively, which were obtained via liquid chip method. According to statistical analysis, a significant difference is found to exist between the two results (p<0.05). 2. The results of western blot method show that the relative contents of PTEN、p-mTOR、p-AKT proteins are0.12±0.03、0.49±0.05、0.76±0.14in PC-9cell, and0.65±0.25、0.15±0.04、0.34±0.07in PC-9/GR cell, respectively. According to statistical analysis, the three molecular markers exhibit significant differences in their expressions in the two kinds of cells (p<0.05).3.Colony formation assay indicates that, under the different doses of6MV X ray (0Gy、1Gy、2Gy.4Gy、6Gy), the survival percentage of PC-9cells decreases from (100.00±0.00) to (6.41±0.37)%, and similarly, the survival percentage of PC-9/GR cells reduces from (100.00±0.00)%to (1.20±0.23)%. According to statistical analysis, the survival percentage of cells in experimental groups shows a significant difference compared with that in the control group (OGy). No obvious difference is observed between the two experimental groups with the dose of1Gy. Besides, in other experimental groups with the same X ray dose, the survival percentages of PC-9/GR cells are all lower than those of PC-9cells, and statistical differences also exist.Conclusion:Under the experimental conditions in vitro, the radiosensitivity of PC-9/GR cell increases in comparison with its parental PC-9cell. The second section:Research on the reversal of drug resistance of gefitinib-resistant lung adenocarcinoma cell caused by T790M mutation after X ray irradiationObjective:To explore the reversal of drug resistance of gefitinib-resistant PC-9/GR cell after X ray irradiation.Method:MTT colorimetric method was used to study the growth inhibition of cells.Results:1.Under the different concentrations of gefitinib (0.1μmol/l、0.5μmol/l、1μmol/l、5μmol/l、1Oμmol/l、20μmol/l、30μmol/l), the growth inhibition percentage of the PC-9/GR cells without irradiation increases from (0.51±0.08)%to (22.23±2.63)%, and the growth inhibition percentage of the PC-9/GR cells irradiated by2Gy6MV X ray increases from (28.12±3.12)%to (68.20±3.55)%. The growth inhibition percentages of the two groups of cells under the same gefitinib concentration show significant differences (p<0.05), according to statistical analysis.2. The IC50value of the PC-9/GR cells irradiated by2Gy6MV X ray is (11.09±1.92) μmol/l, and the IC50value of the PC-9/GR cells without irradiation is (31.78±2.11)μmol/l. By contrast, a statistical difference exists between the two (p<0.05). Conclusion: Under the experimental conditions in vitro, the PC-9/GR cells with2Gy6MV X ray irradiation exhibit higher sensitivity to gefitinib than the PC-9/GR cells without irradiation.