Abstract | PURPOSE:
Pseudolaric acid B (PAB), the naturally occurring diterpenoid isolated from the root bark of Pseudolarix kaempferi Gordon tree (Pinaceae), possesses potent antifungal and pregnancy-terminating effects that may be tightly associated with angiogenesis. This study was to examine its angiogenic inhibition, impact on vascular endothelial growth factor ( VEGF) secretion from tumor cells and the possible mechanism of action. EXPERIMENTAL DESIGN: Angiogenesis inhibition was assessed by the human umbilical vascular endothelial cell proliferation, migration, and tube-formation assays, as well as the chorioallantoic membrane assay. ELISA, reverse transcription-PCR, and Western blotting analyses were performed to examine VEGF protein secretion, mRNA expression, and the possible mechanism in hypoxic MDA-MB-468 cells. RESULTS: PAB displayed potent in vitro antiangiogenic activity shown by inhibiting VEGF-stimulated proliferation and migration and fetal bovine serum-stimulated tube formation of human umbilical vascular endothelial cells in a concentration-dependent manner. Moreover, PAB (10 nmol per egg) significantly suppressed in vivo angiogenesis in the chorioallantoic membrane assay. On the other hand, PAB abrogated hypoxia-induced VEGF secretion from MDA-MB-468 cells via reducing HIF-1alpha protein. Additional analyses using LY294002 and U0126 indicated that the increase in hypoxia-inducible factor 1 (HIF-1)alpha protein level was highly dependent on phosphatidylinositol 3'-kinase and p42/p44 mitogen-activated protein kinase activities in hypoxic MDA-MB-468 cells. However, PAB treatment did not affect the active (phosphorylated) forms of Akt and Erk. Interestingly, the selective proteasome inhibitor MG-132 completely reversed the reduction of HIF-1alpha protein in the PAB-treated MDA-MB-468 cells. CONCLUSIONS: PAB displays the dual antiangiogenic activities of directly inhibiting endothelial cells and abrogating paracrine stimulation of VEGF from tumor cells due to reducing HIF-1alpha protein by promoting its proteasome-mediated degradation in MDA-MB-468 cells, which has potential clinical relevance.
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Authors | Mei-Hong Li, Ze-Hong Miao, Wen-Fu Tan, Jian-Min Yue, Chao Zhang, Li-Ping Lin, Xiong-Wen Zhang, Jian Ding |
Journal | Clinical cancer research : an official journal of the American Association for Cancer Research
(Clin Cancer Res)
Vol. 10
Issue 24
Pg. 8266-74
(Dec 15 2004)
ISSN: 1078-0432 [Print] United States |
PMID | 15623602
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Diterpenes
- Drugs, Chinese Herbal
- HIF1A protein, human
- Hypoxia-Inducible Factor 1, alpha Subunit
- Transcription Factors
- Vascular Endothelial Growth Factor A
- pseudolaric acid B
- Phosphatidylinositol 3-Kinases
- Mitogen-Activated Protein Kinases
- Proteasome Endopeptidase Complex
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Topics |
- Animals
- Blotting, Western
- Breast Neoplasms
(blood supply, metabolism, pathology)
- Cell Movement
(drug effects)
- Cell Proliferation
(drug effects)
- Cells, Cultured
- Chickens
- Chorioallantoic Membrane
(drug effects, metabolism)
- Diterpenes
(therapeutic use)
- Drugs, Chinese Herbal
(therapeutic use)
- Eggs
(analysis)
- Endothelium, Vascular
(drug effects, metabolism)
- Enzyme-Linked Immunosorbent Assay
- Humans
- Hypoxia
- Hypoxia-Inducible Factor 1, alpha Subunit
- Mitogen-Activated Protein Kinases
(metabolism)
- Neovascularization, Pathologic
(metabolism, prevention & control)
- Phosphatidylinositol 3-Kinases
(metabolism)
- Pinaceae
(chemistry)
- Proteasome Endopeptidase Complex
(metabolism)
- Reverse Transcriptase Polymerase Chain Reaction
- Transcription Factors
(metabolism)
- Umbilical Veins
(drug effects, metabolism)
- Vascular Endothelial Growth Factor A
(metabolism)
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