Emodin suppresses hyaluronic acid-induced MMP-9 secretion and invasion of glioma cells

Emodin, an inhibitor of protein tyrosine kinase, possesses antiviral, immunosuppressive, anti-inflammatory and anticancer effects. In the present study, we investigated the effect of emodin on the hyaluronic acid (HA)-induced invasion of human glioma cells. Emodin significantly inhibited the HA-induced invasion through a Matrigel coated chamber, secretion of matrix metal loproteinase (MMP)-2, and HAinduced secretion of MMP-9 in glioma cells. To investigate the possible mechanisms involved in these events, we performed Western blot analysis using phospho-specific antibodies, and found that emodin inhibited phosphorylation of focal adhesion kinase (FAK), extracellular regulated protein kinase (ERK) 1/2 and Akt/PKB; ernodin also suppressed the transcriptional activity of two transcription factors, activator protein-1 (AP-1) and nuclear factor-kappa B (NF-kappa B), in glioma cells. In addition, oral administration of emodin suppressed in vivo MMP secretion by glioma tumors in nude mice. Taken together, our results indicate that emodin can effectively inhibit HA-induced MMP secretion and invasion of glioma through inhibition of FAK, ERK1/2 and Akt/PKB activation and partial inhibition of AP-1 and NF-kappa B transcriptional activities. Consequently, these results provide important insights into emodin as an anti-invasive agent for the therapy of human glioma.