Brazilein和Naphtho[1,2-b]furan-4,5-dione(NFD)對MDA-MB-231乳癌細胞抗轉移機制之研究

Abstract

Brazilein, a bioactive compound isolated from Caesalpinia sappan L., has long been used in oriental folk medicines. During treatment with non-toxic doses of brazilein, cell migration and invasion were markedly suppressed using wound-healing assay and Boyden chamber assay. Western blot, reversed transcription-PCR and gelatin zymography analysis showed that brazilein significantly and selectively suppressed the expression and activity of MMP-2 in a concentration-dependent manner. In addition, brazilein significantly decreased the nuclear level of NF-κB, increased inhibitor of kappa Bα (IκBα) through preventing phosphorylation of upstream signal IκB kinase (IKK), and pretreatment with a specific NF-κB inhibitor PDTC also reduced MMP-2 activity and cell migration. Our biochemical assays indicated that brazilein potently suppressed the phosphorylation of p38 MAPK, phosphatidylinositide-3-kinase (PI3K) and Akt, while it did not affect phosphorylation of extracellular signal regulating kinase (ERK)1/2 and c-Jun N-terminal kinase (JNK). Additionally, the treatment of inhibitors specific for p38 MAPK (SB203580) or PI3K (wortmannin) to MDA-MB-231 cells could result in a reduced expression of MMP-2, concomitantly with a marked inhibition on cell migration. Taken together, these results demonstrate that brazilein inhibits the migration and invasion of MDA-MB-231 cells by reducing MMP-2 activity through suppressing PI3K/Akt and p38 MAPK signaling pathways and inhibiting NF-κB activity. Naphtho[1,2-b]furan-4,5-dione (NFD), a bioactive component of Avicennia marina, has been demonstrated to display anti-cancer activity. Activation of epidermal growth factor receptor (EGFR)-induced signaling pathway has been correlated with cancer metastasis in various tumors, including breast carcinoma. We use EGF as a metastatic inducer of MDA-MB-231 cells to investigate the effect of NFD on cell metastasis. NFD suppressed EGF-mediated protein levels of c-Jun and c-Fos, and reduced MMP-9 expression and activity, concomitantly with a marked inhibition on cell migration and invasion without obvious cellular cytotoxicity. NFD abrogated EGF-induced phosphorylation of EGF receptor (EGFR) and phosphatidylinositol 3-kinase (PI3K)/Akt. The specific PI3K inhibitor, wortmannin, significantly blocked EGF-induced cell migration and invasion. Furthermore, the EGFR inhibitor AG1478 inhibited EGF-induced MMP-9 expression and cell metastasis, as well as the activation of PI3K/Akt, suggesting that PI3K/Akt activation occur downstream of EGFR activation. These findings suggest that NFD inhibited the EGF-induced invasion and migration of MDA-MB-231 cells via EGFR-dependent PI3K/Akt signaling, leading to the down-regulation of MMP-9 expression. These results provide a novel mechanism to explain the role of NFD as a potent anti-metastatic agent in MDA-MB-231 cells.