Background and objective Recent studies have indicated that Nm23-H1 is found in the nucleus,but previous studies have been based on the overexpression or suppression of Nm23-H1 in the cytoplasm.Due to the lacking nuclear localization signal of Nm23-H1,these results cannot reflect or repeat cells in which Nm23-H1 mainly positioned in nuclei and whether they cause clinical biological effects.Therefore,to explore the effects of transposing Nm23-H1 from the cytoplasm to the nucleus during lung cancer cell proliferation,a vector with a nuclear localization signal of Nm23-H1 was constructed and A549 cells were transfected.Methods Gene recombination technology was used to construct pLentis-CMV-NME1-IRES2-PURO lentiviral vectors using a nuclear localization signal sequence,and the recombinant plasmid was verified using restriction enzyme analysis and sequencing.Nm23-H1 positioning and expression were performed after the stably transfected A549 cells were assessed by Western blot and confocal laser scanning microscope.The A549 cell proliferation was assessed using a cell counting kit-8.Flow cytometry was performed to assess the cell cycle distribution ofA549 cells.Results The directional Nm23-H1 lentiviral vector was successfully constructed within the nucleus.Compared with that of the empty vector group,the proliferation rates of the transfection groups at 72 h,96 h,and 120 h were remarkably increased (P＜0.000,1).Moreover,the empty vector group ofA549 cells in the G0/G1 phase proportion was 35.69％,which was higher than the 28.28％ of the transfection group (t=1.461,P=0.217);furthermore,the transfection group ofA549 cells in the G2/M phase proportion was 58.7％ and that of the empty vector group was 31.30％ (t=4.560,P=0.010).Conclusion Human lung adenocarcinoma cell line A549 cells of Nm23-H1 nuclear localized mainly in the G2/M phase and the nuclear Nm23-H1 promoted A549 cell proliferation in vitro.