Licochalcone A inhibits the invasive potential of human glioma cells by targeting the MEK/ERK and ADAM9 signaling pathways

Licochalcone A (LicA) has been reported to possess antitumor properties. However, its effect on human glioma cells remains unknown. In this study, we observed that LicA significantly suppressed the ADAM9 expression and the migration and invasion activities of human glioma cells (M059K, U-251 MG, and GBM8901) and exhibited no cell cytotoxicity. The human proteinase antibody array and immunoblot analysis indicated that the LicA treatment inhibited the expression of ADAM9 protein in human glioma cells. Recombinant human ADAM-9 (Rh-ADAM9) treatment significantly reversed the LicA-induced reduction in the ADAM9 level and the migration and invasion activities of human glioma cells. Additionally, the phosphorylation/activation of the mitogen-activated protein kinase kinase (MEK)-extracellularly responsive kinases (ERK) signaling pathway was significantly suppressed in LicA-treated human glioma cells. Cotreatment with LicA and PD98059 synergistically inhibited the ADAM9 expression, cell migration, and cell invasion, which suggested that the MEK-ERK signaling pathway was involved in the LicA-induced inhibition of the ADAM9 expression and the invasion activity of human glioma cells. These findings are the first evidence of LicA's anti-invasive properties against human glioma cells.