Hirsutenone inhibits phorbol ester-induced upregulation of COX-2 and MMP-9 in cultured human mammary epithelial cells: NF-κB as a potential molecular target

Inappropriate upregulation of cyclooxygenase-2 (COX-2) and matrix metalloproteinases (MMPs) has been implicated in the pathogenesis of various types of cancer. In the present study, we investigated the effects of hirsutenone, a diarylheptanoid isolated from the medicinal plant Alnus hirsuta var. sibirica, on the expression of COX-2 and MMP-9 induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) in MCF10A human breast epithelial cells. Treatment of MCF10A cells with TPA led to the expression of COX-2 and MMP-9. Hirsutenone at 12 μM inhibited the TPA-induced COX-2 expression at both the transcriptional and posttranscriptional levels. Hirsutenone also suppressed the synthesis of prostaglandin E2, one of the major products of COX-2, and its catalytic activity. The upregulation of MMP-9 by TPA was also significantly reduced by hirsutenone. Likewise, hirsutenone attenuated the invasiveness and motility of MCF10A cells stimulated with TPA. Hirsutenone blocked the TPA-induced DNA binding of nuclear factor kappa B (NF-κB) and translocation of p65, the functionally active NF-κB subunit, to the nucleus. The luciferase reporter gene assay revealed that hirsutenone abrogated the transcriptional activity of NF-κB. Treatment of MCF10A cells with N-alpha-Tosyl-l-phenylalanine chloromethyl ketone, a specific inhibitor of NF-κB, reduced the TPA-induced expression of COX-2 and MMP-9. In summary, hirsutenone inhibits the TPA-induced upregulation of COX-2 and MMP-9 in human breast epithelial cells, possibly by targeting NF-κB, which may contribute to its chemopreventive effects.