Oroxylin A inhibits matrix metalloproteinase-2/9 expression and activation by up-regulating tissue inhibitor of metalloproteinase-2 and suppressing the ERK1/2 signaling pathway.

Matrix metalloproteinases (MMPs) play important roles in the invasion and migration of cancer cells. In this study, we used in vitro and in vivo assays to examine the inhibitory effects of oroxylin A, one of the main bioactive flavonoid extracted from Scutellaria radix, on the human breast carcinoma cell MDA-MB-231 invasion and migration. We found that oroxylin A can suppress cell adhesion, invasion and migration in a concentration-dependent manner. Moreover, oroxylin A led to the reduction of the activity and expression levels of MMP-2 and MMP-9 in gelatin zymography, real-time PCR and western blotting analysis. Further elucidation of the mechanism revealed that oroxylin A increased the expression of tissue inhibitor of metalloproteinase-2 (TIMP-2), the endogenous inhibitor of MMP-2, and repressed the phorbol-12-myristate-13-acetate (PMA)-induced translocation of protein kinase Cδ (PKCδ), phosphorylation of extracellular signal-regulated kinase (ERK1/2) and binding activity of the transcription factor activator protein-1 (AP-1) which are upstream signaling molecules in MMP-9 expression. Our results also indicated that oroxylin A inhibited the lung metastasis of murine melanoma cell B16-F10 in vivo. Therefore, we proposed that oroxylin A might be developed as a therapeutic potential candidate for the treatment of cancer metastasis.