Ascochlorin suppresses oxLDL-induced MMP-9 expression by inhibiting the MEK/ERK signaling pathway in human THP-1 macrophages

The critical initiating event in atherogenesis involves the invasion of monocytes through the endothelial walls of arteries and the transformation of monocytes from macrophages into foam cells. Human THP‐1 monocytic cells can be induced to differentiate into macrophages by phorbol myristate acetate (PMA) and can then be converted into foam cells by exposure to oxidized low‐density lipoprotein (oxLDL). Also, during a chronic inflammatory response, monocytes/macrophages produce the 92‐kDa matrix metalloproteinase‐9 (MMP‐9) that may contribute to the extravasation, migration, and tissue remolding capacities of the phagocytic cells. Here, we investigate the effect of ascochlorin (ASC), a prenylphenol antiviral compound from the fungus Ascochyta viciae, on oxLDL‐induced MMP‐9 expression and activity in human THP‐1 macrophages. ASC reduced oxLDL‐induced MMP‐9 expression and activity in a time‐dependent and dose‐dependent manner. Also, an analysis of MMP‐9 activity using pharmacologic inhibitors showed that ASC inhibits MMP‐9 activity via the extracellular signal‐regulated kinase 1 and kinase 2 pathways. Our results suggest that ASC may be useful as a potent clinical antiatherogenic agent, a topic of considerable interest in the biological chemistry of chemotherapeutic agents. J. Cell. Biochem. 102: 506–514, 2007. © 2007 Wiley‐Liss, Inc.