Received for publication December 8, 2004.
Revised June 14, 2005.
Accepted for publication July 1, 2005.

Diosgenin induces HIF-1 activation and angiogenesis through estrogen receptor-related PI3K/Akt and p38 MAPK pathways in osteoblasts

Abstract

Diosgenin, extracted from the root of Wild Yam (Dioscorea villosa), has been reported to demonstrate tremendous opportunity for medical application. Vascular endothelial growth factor-A (VEGF-A) plays an important role in bone-related angiogenesis, a critical process occurring during bone formation and fracture healing. Here we examine whether diosgenin is able to induce VEGF-A expression as well as to promote angiogenesis in osteoblasts. For murine MC3T3-E1 preosteoblast-like cells, VEGF-A mRNA and protein expression appeared to be significantly elevated in response to diosgenin in a concentration-dependent fashion. Conditioned media prepared from cells treated with diosgenin induced strong angiogenic activity in either in vitro or ex vivo angiogenesis assay. Furthermore, diosgenin treatment increased the stability and activity of HIF-1 protein. Inhibition of HIF-1 activity by transfection with DN-HIF-1 significantly diminished diosgenin-mediated VEGF-A up-regulation. The use of pharmacological inhibitors or genetic inhibition revealed that both the PI3K/Akt and p38 signalling pathways were potentially required for diosgenin-induced HIF-1 activation and subsequent VEGF-A up-regulation. Of interest, estrogen receptor binding assay revealed that diosgenin has the strong ability to replace [³H]-estradiol bind to estrogen receptor (IC(50):10 nM). In addition, the specific estrogen receptor antagonists ICI 182,780 and tamoxifen were noted to be able to strongly inhibit the diosgenin-induced src kinase-dependent Akt and p38 MAPK activation. Taken together, such results provide evidence that diosgenin up-regulates VEGF-A and promotes angiogenesis in preosteoblast-like cells by a HIF-1-dependent mechanism involving the activation of src kinase, p38 MAPK and Akt signalling pathways via estrogen receptor.

Key words: Sex hormones, Src and other nonreceptor tyrosine kinases, MAP Kinase, P38 MAP Kinase, DNA binding sites, Promoter analysis, Fluorescence techniques, Receptor binding studies, Overexpression, Angiogenesis

This article has been cited by other articles:

				R. Aesoy, B. C. Sanchez, J. H. Norum, R. Lewensohn, K. Viktorsson, and B. Linderholm An Autocrine VEGF/VEGFR2 and p38 Signaling Loop Confers Resistance to 4-Hydroxytamoxifen in MCF-7 Breast Cancer Cells Mol. Cancer Res., October 1, 2008; 6(10): 1630 - 1638. [Abstract] [Full Text] [PDF]

				M.-T. Lin, I-H. Kuo, C.-C. Chang, C.-Y. Chu, H.-Y. Chen, B.-R. Lin, M. Sureshbabu, H.-J. Shih, and M.-L. Kuo Involvement of Hypoxia-inducing Factor-1{alpha}-dependent Plasminogen Activator Inhibitor-1 Up-regulation in Cyr61/CCN1-induced Gastric Cancer Cell Invasion J. Biol. Chem., June 6, 2008; 283(23): 15807 - 15815. [Abstract] [Full Text] [PDF]

				H. Buteau-Lozano, G. Velasco, M. Cristofari, P. Balaguer, and M. Perrot-Applanat Xenoestrogens modulate vascular endothelial growth factor secretion in breast cancer cells through an estrogen receptor-dependent mechanism J. Endocrinol., February 1, 2008; 196(2): 399 - 412. [Abstract] [Full Text] [PDF]

				J.-L. Su, C.-Y. Yang, M. Zhao, M.-L. Kuo, and M.-L. Yen Forkhead Proteins Are Critical for Bone Morphogenetic Protein-2 Regulation and Anti-tumor Activity of Resveratrol J. Biol. Chem., July 6, 2007; 282(27): 19385 - 19398. [Abstract] [Full Text] [PDF]

				A. A. Kazi and R. D. Koos Estrogen-Induced Activation of Hypoxia-Inducible Factor-1{alpha}, Vascular Endothelial Growth Factor Expression, and Edema in the Uterus Are Mediated by the Phosphatidylinositol 3-Kinase/Akt Pathway Endocrinology, May 1, 2007; 148(5): 2363 - 2374. [Abstract] [Full Text] [PDF]