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ObjectiveMelittin (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.Methodology/Principal FindingsMEL 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.ConclusionsMEL 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.

We have previously reported that N-myc downstream regulated gene-1 (NDRG1) is an early inducible protein during the maturation of mouse bone marrow-derived mast cells (BMMCs) toward a connective tissue mast cell-like phenotype. To clarify the function of NDRG1 in mast cells and allergic responses, we herein analyzed mast cell-associated phenotypes of mice lacking the Ndrg1 gene. Allergic responses including IgE-mediated passive systemic and cutaneous anaphylactic reactions were markedly attenuated in Ndrg1-deficient mice as compared with those in wild-type mice. In Ndrg1-deficient mice, dermal and peritoneal mast cells were decreased in number and morphologically abnormal with impaired degranulating ability. Ex vivo, Ndrg1-deficient BMMCs cocultured with Swiss 3T3 fibroblasts in the presence of stem cell factor, a condition that facilitates the maturation of BMMCs toward a CTMC-like phenotype, displayed less exocytosis than replicate wild-type cells after the cross-linking of FcεRI or stimulation with compound 48/80, even though the exocytotic response of IL-3-maintained, immature BMMCs from both genotypes was comparable. Unlike degranulation, the production of leukotriene and cytokines by cocultured BMMCs was unaffected by NDRG1 deficiency. Taken together, the altered phenotypes of Ndrg1-deficient mast cells both in vivo and ex vivo suggest that NDRG1 has roles in the terminal maturation and effector function (degranulation) of mast cells.

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.

Ascofuranone has been shown to have antitumor activity, but the precise molecular mechanism by which it inhibits the proliferation of cancer cells remains unclear. Here, we study the effects of ascofuranone on cell cycle progression in human cancer cells and find that ascofuranone induces G 1 arrest without cytoxicity with upregulation of p53 and p21 WAF1/CIP1 while downregulating c-Myc and G 1 cyclins. Chromatin immunoprecipitation assay and RNA interference studies with cells deficient in p53 and p21 show that ascofuranone induces p21 WAF1/CIP1 expression and subsequent G 1 arrest through the release of p21 WAF1/CIP1 promoter from c-Myc-mediated transcriptional repression, independent of p53. Ascofuranone-induced p21 WAF1/CIP1 associates with CDK2 and prevents CDK2-cyclin E complex formation, leading to the inactivation of E2F transcriptional activity. These results suggest that ascofuranone upregulates p21 WAF1/CIP1 through p53-independent suppression of c-Myc expression, leading to cytostatic G 1 arrest. Thus, ascofuranone represents a unique natural antitumor compound that targets c-Myc independent of p53. Mol Cancer Ther; 9(7); 2102-13. ©2010 AACR.