Objective      To determine the effect of lymphocyte microparticles (LMPs) on the cell cycle of airway epithelial cells and investigate the underlying mechanism.       Methods      LMPs of 20 μg/ml was treated human normal airway epithelial cells at logarithmic growth period for 0

4

8

16

20 and 24 h respectively. RT-polymerase chain reaction (PCR) was used to detect the expression of P21 and P27 at mRNA level. Western blot analysis was employed to test the expression of P21

P27

Foxo1

p-Foxo1

AKT and p-AKT at protein level. I

mmunocytochemical assay was to test the nuclear localization of Foxo1.       Results      LMPs of 20 μg/ml resulted in an obvious increase of P21 and P27 at mRNA and protein levels (P0.01). No change was found in Foxo1 and AKT protein levels (P0.05)

but their phosphorylated proteins were evidently down-regulated (P0.01).       Conclusion      LMPs upregulates P21 and P27 expression and causes cell cycle arrested at G

1

phase in the airway epithelial cells through AKT/Foxo1 signaling pathways.