Cyclic Strain Promotes Migration and Proliferation of Human Periodontal Ligament Cell via PI3K Signaling Pathway

Mechanical stimulations have significant impact on cell growth and migration, while little is known on the mechanism of human periodontal ligament cells (hPDLCs) behavior alteration under cyclic strain application. To elucidate the role of PI3K/Akt signaling pathway in cyclic strain-induced migration and proliferation of hPDLCs, 10 or 20%-elongation of cyclic strain at 0.1 Hz-frequency was applied to hPDLCs for 6 h or 24 h with FX-4000T system. The expressions of MMP-13 and p-Akt were examined by Western blotting, and cell proliferation was also detected by BrdU assay. A significant enhance of hPDLCs migration was observed after 24 h of cyclic strain application evaluated with wound healing method, and 20% was found to be more sensitive than 10% of cyclic strain. The strain also significantly increased MMP-13 and p-Akt expressions in hPDLCs as compared with the static. More importantly, the cyclic strain-induced hPDLC migration was suppressed by PI3K/Akt inhibitor wortmannin, and blocked with MMP-13 RNAi pretreatment before loading of 10 or 20%-strain. Additionally, wortmannin suppressed not only the activation of p-Akt, MMP-13 and PCNA, but also the cell proliferation under cyclic strain application in hPDLCs. The findings suggest that cyclic strain promotes the migration and proliferation of hPDLCs by up-regulating the expressions of MMP-13 and PCNA through PI3K/Akt signaling pathway.