The Research On Change Of Chemosensitivity Of Gefitinib-resistant Lung Adenocarcinoma Cell Caused By EGFR-T790M Mutation

BackgroundsIn recent years, targeted therapy has become an important means of NSCLC systemic therapy, but secondary resistance is inevitable after a time of medication. Now, turning to chemotherapy is still one of the effective treatments while there is no final conclusion of the treatment after secondary resistance of targeted treatment in NSCLC. So it is significant to choose chemotherapy drugs sensitive to the targeted drug-resistant NSCLC, which is worth further study.This test detects the sensitivity of lung adenocarcinoma cell line PC-9and PC-9/GR to cisplatin, gemcitabine, vinorelbine, paclitaxel, docetaxel, pemetrexed, and the expression of ERCC1, TUBB3, TS, RRM1mRNA and protein in two cell lines, to get preclinical evidence for subsequent chemotherapy drugs selection of EGFR-TKIs secondary resistance patients caused by EGFR-T790M mutation.Materials and methods1、PC9cells was placed in1640complete medium containing10%fetal bovine serum; PC9/GR cells was placed in1640complete medium containing gefitinib with concentration of10mmol/L and10%fetal calf serum. Both of them was placed in37°Culture incubator with5%CO2and humidity of80%.2、MTT assay was used to detect the IC50values of cisplatin, gemcitabine, vinorelbine, paclitaxel,docetaxel, pemetrexed to PC9and PC9/GR cells.3、Luminex method and Western-Blot method was used respectively to detect the expression levels of ERCC1, TUBB3, TS,RRM1mRNA and protein in PC9and PC9/GR cells.4、SPSS19.0statistical package was used for data analysis,and all the data was expressed as mean±standard deviation. T test was used to analyze the difference between two groups, while P<0.05was cencidered as statistical significance.Resμlts1、MTT method shows that the IC50values of cisplatin, gemcitabine, pemetrexed to PC9/GR cells was significantly higher than that of PC9cells (P<0.05), while the IC50values of vinorelbine, paclitaxel, docetaxel to PC9/GR cells was significantly decreased (P<0.05).2、Luminex method shows the expression of ERCC1, TS, RRM1mRNA in PC9/GR cells was significantly increased than that of PC9cells (P<0.05), while the expression of TUBB3mRNA was significantly decreased (P<0.05).3、Western-Blot method shows the expression of TUBB3, TS,RRM1protein in PC9/GR cells was significantly increased than that of PC9cells (P<0.05), while TUBB3protein expression of PC9/GR cells was significantly decreased (P<0.05).Conclusion1、The chemosensitivity of lung adenocarcinoma with EGFR-T790M mutation is changed. It has decreased sensitivity to cisplatin, gemcitabine, pemetrexed and increased sensitivity to vinorelbine, paclitaxel,docetaxel.2、The expression of ERCC1, RRM1,TS was significantly increas-ed, while TUBB3was significantly reduced on lung adenocarcinoma with EGFR-T790M mutation, which maybe the reason for the changes of its chemosensitivity.This article includes3figures,3tables and49references.