Effect Of TK1 On Drug Resistance Of Cisplatin-resistant Non-small Cell Lung Cancer A549/DDP Cells

Objective: To investigate the effect of Thymidine Kinase 1（TK1）on cisplatin sensitivity of A549/DDP cells from non-small cell lung cancer（NSCLC）.Additionally,we will investigate whether it is possible to affect cisplatin sensitivity of NSCLC A549/DDP cells through the mechanism of DNA damage and repair.Methods: Lentiviruses overexpressing and interfering with TK1 were used to transfect A549/DDP cells to develop TK1 overexpressing stable transfection cell lines（oe-TK1）,overexpression control groups（oe-NC）,interference stable cell lines（sh-TK1）,and interference control groups（sh-NC）.The mediated effects on cell proliferation,cisplatin resistance IC50,and the expression of multidrug resistance-related protein 1（MRP1）,multidrug resistance gene 1（MDR1）,lung cancer resistance-related protein 1（LRP1）,and Phosphorylated H2 A Histone Family Member X（γ-H2AX）were investigated using Western blot,MTT,and plate clone formation assays.Results: The stable cell lines of overexpression,interference and control groups were successfully constructed.MTT results showed that the proliferation ability of the oe-TK1 group was significantly higher than that of the oe-NC group(P_24h=0.0014;P_48h=0.0157;P_72h=0.0122),and the proliferation ability of the sh-TK1 group was significantly lower than that of the sh-NC group（P24h=0.0041;P72h=0.0037）.The plate colony formation assay results showed that the number of clone formations in the oe-TK1 group was significantly higher than that in the oe-NC group.Additionally,the IC50 results showed that the IC50 of the oe-TK1 group was significantly higher than that of the oe-NC group（30.20 μ g / m L vs.20.92 μ g / m L）.In comparison,the IC50 of the sh-TK1 group was significantly lower than that of the sh-NC group（25.46 μ g / m L vs.38.33 μ g / m L）.Western Blot analysis showed that LRP1 and MDR1 expression in the oe-TK1 group was significantly higher than in the oe-NC group(P_LRP1=0.0199;P_MDR1=0.0021).However,the expression of the marker protein γ-H2 AX damaged by DNA was significantly lower than in the oe-NC group（P<0.001）.Furthermore,MRP1,MDR1,and LRP1 protein expressions were significantly lower in the sh-TK1 group than in the sh-NC group(P_MRP1=0.0373;P_MDR1=0.0023;P_LRP1=0.0191).Meanwhile,the expression of γ-H2 AX was significantly higher than that in the sh-NC group（P<0.0001）.Conclusion: TK1 enhances A549/DDP cell proliferation and cisplatin resistance,and these effects may be partly due to its role in DNA repair mechanisms.