Salidroside, 8(E)-Nuezhenide, and Ligustroside from Ligustrum japonicum Fructus Inhibit Expressions of MMP-2 and -9 in HT 1080 Fibrosarcoma

A phenyl ethanoid, salidroside (SAL), and two secoiridoids, 8(E)-nuezhenide (NZD) and ligustroside (LIG), were isolated from fruits of Ligustrum japonicum, used as traditional folk medicine, and their chemical structures were elucidated by the comparison of spectral data with published literature. Matrix metalloproteinases (MMPs) are major enzymes that play crucial roles in the metastasis and invasive behavior of tumors. In particular, MMP-2 and MMP-9, regulated by the MAPK signaling pathways, including p38, ERK and JNK, are known to play a key role in the degradation of the basement membrane. In the present study, the effects of SAL, NZD and LIG on the expression of MMP-2 and -9 were examined in phorbol 12-myristate 13-acetate (PMA)-induced HT 1080 cells. All the compounds significantly lowered the amount of MMP-2 and MMP-9 released, as determined by gelatin zymography and ELISA. In addition, the mRNA and protein expression levels of MMP-2 and MMP-9 were significantly suppressed, as measured by RT-PCR and Western blotting. According to the Western blotting assay, SAL and LIG effectively reduced the expression of MMP-2 in a dose-dependent manner. NZD lowered the expression of MMP-9 in a similar way. The phosphorylation of p38, ERK and JNK was also significantly suppressed by these compounds. These findings suggest that all the compounds regulate the release and expression of MMP-2 and MMP-9 via MAPK signaling pathways.