The expression of matrix metalloproteinases (MMPs) has been implicated in the invasion and metastasis of cancer cells. Here we examined the effect of ascochlorin, a prenyl-phenol anti-tumor compound from the fungus Ascochyta viciae, on the regulation of signaling pathways that control MMP-9 expression in human renal carcinoma (Caki-1) cells. Ascochlorin reduced the invasive activity of Caki-1 cells and inhibited phorbol 12-myristate 13-acetate-induced increases in MMP-9 expression and activity in a dose-dependent manner. Reporter gene, electrophoretic mobility shift, kinase inhibitor assays, and in vitro kinase assay showed that ascochlorin inhibits MMP-9 gene expression by suppressing activation of the nuclear transcription factor activator protein-1 (AP-1) via the extracellular signal-regulated kinase 1 and 2 pathway. The AP-1 family member most specifically affected by ascochlorin was Fra-1. Ascochlorin did not affect the activation of the c-Jun N-terminal or p38 kinase pathways. Moreover, transfection of Caki-1 cells with AP-1 decoy oligodeoxynucleotides resulted in the suppression of phorbol 12-myristate 13-acetate-induced MMP-9 expression and invasion. In conclusion, ascochlorin represents a unique natural anti-tumor compound that specifically inhibits MMP-9 activity through suppression of AP-1-dependent induction of MMP-9 gene expression.

The expression of matrix metalloproteinase-9 (MMP-9) has been implicated in the invasion and metastasis of cancer cells. Here, we found that an antitumor antibiotic, ascofuranone, inhibits invasion and MMP-9 induction induced by phorbol myristate acetate (PMA) in human cell lines. Ascofuranone also inhibits the protein expression and transcription of MMP-9 induced by tumor necrosis factor-α. The inhibition of MMP-9 induction was observed in human cancer cell lines as well as primary rat mesangial cells. Furthermore, as evidenced by MMP-9 promoter and electrophoretic mobility shift assays, ascofuranone specifically inhibited MMP-9 gene expression by blocking PMA-stimulated activation of activator protein-1 (AP-1). In addition, ascofuranone suppressed PMA-induced phosphorylation of Ras, Raf, MEK and extracellular signal-regulated kinase (ERK), upstream factors involved in AP-1activation, whereas the phosphorylation of p38 and JNK/mitogen-activated protein kinase was not affected by ascofuranone, suggesting that the primary target of ascofuranone for suppression of the AP-1 induction is present in upstream of ERK signaling pathway. These results suggest that the suppression of MMP-9 expression, at least in part, contributes to the antitumor activity of ascofuranone.

Matrix metalloproteinase-9 (MMP-9) plays an important role in the invasion and metastasis of cancer cells. In this study, we examined the inhibitory effect of bee venom (BV) and its major peptides, melittin and apamin, on PMA-induced invasion induced by MMP-9 expression in Caki-1 renal cancer cells. BV and melittin, but not apamin, significantly suppressed PMA-induced invasion by inhibiting MMP-9 expression in Caki-1 cells. Furthermore, as evidenced by MMP-9 promoter assays, melittin inhibited MMP-9 gene expression by blocking the PMA-stimulated activations of activator protein-1 (AP-1) and nuclear factor-kappa B (NF-κB). In addition, melittin suppressed the PMA-induced phosphorylations of ERK and JNK mitogenactivated protein kinases, upstream factors involved in Ap-1 and NF-κB. These results suggest that the suppression of MMP-9 expression contributes to the anti-tumor properties of melittin.

Delphinidin, a polyphenol that belongs to the group of anthocyanidins and is abundant in many pigmented fruits and vegetables, possesses important antioxidant, anti‑inflammatory, anti-mutagenic and anticancer properties. In the present study, we investigated the inhibitory effects of delphinidin on vascular endothelial growth factor (VEGF) expression, an important factor involved in angiogenesis and tumor progression, in A549 human lung cancer cells. Delphinidin inhibited CoCl2- and epidermal growth factor (EGF)-induced VEGF mRNA expression and VEGF protein production. Delphinidin also decreased CoCl2- and EGF-stimulated expression of hypoxia‑inducible factor (HIF)‑1α, which is a transcription factor of VEGF. Delphinidin suppressed CoCl2- and EGF-induced hypoxia‑response element (HRE) promoter activity, suggesting that the inhibitory effects of delphinidin on VEGF expression are caused by the suppression of the binding of HIF-1 to the HRE promoter. We also found that delphinidin specifically decreased the CoCl2- and EGF-induced HIF-1α protein expression by blocking the ERK and PI3K/Akt/mTOR/p70S6K signaling pathways, whereas the p38-mediated pathways were not involved. In animal models, EGF-induced new blood vessel formation was significantly inhibited by delphinidin. Therefore, our results indicate that delphinidin has a potentially new role in anti‑angiogenic action by inhibiting HIF-1α and VEGF expression.

Melittin (MEL), a major component of bee venom, has been associated with various diseases including arthritis, rheumatism and various cancers. In this study, the anti-angiogenic effects of MEL in CaSki cells that were responsive to the epidermal growth factor (EGF) were examined. MEL decreased the EGF-induced hypoxia-inducible factor-1α (HIF-1α) protein and significantly regulated angiogenesis and tumor progression. We found that inhibition of the HIF-1α protein level is due to the shortened half-life by MEL. Mechanistically, MEL specifically inhibited the EGF-induced HIF-1α expression by suppressing the phosphorylation of ERK, mTOR and p70S6K. It also blocked the EGF-induced DNA binding activity of HIF-1α and the secretion of the vascular endothelial growth factor (VEGF). Furthermore, the chromatin immunoprecipitation (ChIP) assay revealed that MEL reduced the binding of HIF-1α to the VEGF promoter HRE region. The anti-angiogenesis effects of MEL were confirmed through a matrigel plus assay. MEL specifically suppressed EGF-induced VEGF secretion and new blood vessel formation by inhibiting HIF-1α. These results suggest that MEL may inhibit human cervical cancer progression and angiogenesis by inhibiting HIF-1α and VEGF expression.