Objective To study the effect of arsenic trioxide on the invasion of human tongue squamous carcinoma cell line CAL-27 in vitro and in vivo and explore the underlying mechanisms. Methods Adhesion assay, Transwell chamber membrane invasion culture system, immunofluorescence and Western Blot were performed to detect the effect of arsenic trioxide on adhesion, migration and invasion of CAL-27 cells in vitro. Immunohistochemical and Western Blot assays were used to study the protein levels of CD44, matrix metalloproteinases(MMP)-2 and MMP-9 in vivo. Results In vitro, arsenic trioxide at lower-dose could significantly reduce abilities of CAL-27 cells to adhere, migrate and invade(P
