Cell proliferation and migration are important repair mechanisms in cell defect type mucosal injuries, such as peptic ulcers. To evaluate the level of cell restitution in vitro, we established a normalized assay system for analyzing the area of a tissue defect created in the center of a cultured cell layer. Although proton pump inhibitors are known to be potently effective in the treatment of peptic ulcers by inducing acid suppression, they are also effective in low-acid conditions, such as in gastric ulcers associated with severe atrophic gastritis of the corpus. The present study was designed to examine the pH-independent effect of lansoprazole (LPZ) on cell restitution in vitro. The mouse gastric mucosal cell line, GSM06, was cultured to confluence. A 4-fluoric ethylene-tipped aluminum stick was then used to produce a cell-free area in the center of the culture well. After measuring the area of the cell defect using a digital analyzer equipped with an inverted microscope, LPZ was added to each well; the area of the residual cell defect was then measured 6 and 24 hours after LPZ administration. To investigate the involvement of the p44/p42 mitogen-activated protein kinase (MAPK) and p38 MAPK in this process, PD98059 (a MEK inhibitor) or FR167653 (a p38 MAPK inhibitor) was added to the cell cultures. In a separate experiment, GSM06 cells were cultured to the subconfluent level, each test agent was added, and the cell number in each well was measured using an MTT assay 16 hours after the administration of the agents. Six hours after the addition of LPZ, a slight but significant increase in the cell restitution rate was observed in the LPZ-treated groups compared with that in the control group. After 24 hours, a further significant increase in the cell restitution rate was observed in the LPZ groups compared with that in the control group. While the addition of PD98059 significantly attenuated the cell restitution rate in the LPZ groups, the addition of FR167653 had no such effect. The total cell number in the subconfluent cell cultures was significantly increased in the LPZ-treated groups compared with that in the control group. In conclusion, LPZ promotes the healing of injured gastric mucosal cells following injury by enhancing cell proliferation and migration. Furthermore, the mechanism by which cell proliferation and migration is promoted by LPZ may involve the activation of p44/p42 MAPK.
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