Abstract: Objective To explore the role of P2X7 receptor (P2X7R) in migration and invasion of mouse Lewis lung cancer (LLC) cells and examine the tumorigenic ability of LLC cells in P2X7R-knockout mice. Methods RT-PCR was used to examine P2X7R mRNA expression in LLC cells. LLC cells were treated with ATP (as a P2X7R agonist) or 2'- 3'- O- (4-benzoyl- benzoyl)-ATP (BzATP) (a P2X7R agonist) with or without pretreatment with P2X7R antagonist oxATP or A438079. The changes in migration and invasive abilities of the cells were evaluated using wound healing assay and Transwell assay; Western blotting was performed to determine the activation level of the key proteins in the AKT signaling pathway. The effects of BzATP, A438079, and LY294002 (a inhibitor of the PI3K/AKT pathway) on migration and invasion of LLC cells were also examined. In wild-type (WT) and P2X7R knockout (P2X7-/-) C57BL/6 mice, the growth of subcutaneous LLC cell xenografts were observed by measuring tumor volume and weight. Results P2X7R expression was detected in LLC cells. Treatment with P2X7R agonist significantly enhanced migration and invasion abilities of LLC cells, and this effect was inhibited by application of P2X7R antagonists (P<0.001). Western blotting showed that BzATP treatment of LLC cells significantly increased the expression level of p-AKT protein, which was obviously lowered by treatment with P2X7R antagonist (P<0.01). P2X7R antagonist strongly inhibited BzATP-induced enhancement of LLC cell migration and invasion (P<0.001). In the tumor- bearing mice, the tumor volume and weight were significantly lower in P2X7-/- mice than in WT mice (P<0.05). Conclusion P2X7R promotes migration and invasion of LLC cells by activating the AKT signaling pathway, and LLC cells show lowered tumorigenic capacity in P2X7-/- mice.

Key words: P2X7 receptor; Lewis lung cancer; migration; invasion; AKT signaling pathway