Effect of Nm23-H1 Nuclear Localization on Proliferation of 
Human Lung Adenocarcinoma Cell Line A549

Abstract

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 of A549 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 of A549 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 of A549 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.

Keywords

• Lung neoplasms
• Nm23-H1
• Nuclear localization
• Cell cycle
• Cell proliferation