Ugonin K-stimulated osteogenesis involves estrogen receptor-dependent activation of non-classical Src signaling pathway and classical pathway.

Abstract

We have reported previously that ugonin K, a flavonoid isolated from Helminthostachys zeylanica (L.) Hook, potently induces cell differentiation and mineralization of MC3T3-E1 mouse osteoblast-like cells. Here we aimed to elucidate whether ugonin K evoked osteogenesis required interaction with estrogen receptor. Results showed that ugonin K induced increases in alkaline phosphatase (ALP) activity, expressions of bone sialoprotein (BSP) and osteocalcin (OCN), and subsequent bone nodule formation were concentration-dependently inhibited by estrogen receptor antagonist ICI 182,780, suggesting that an estrogen receptor-dependent pathway was involved. In the presence of ICI 182,780, ugonin K induced up-regulation of the expressions of runt-related transcription factor 2 (Runx2) and osterix was also significantly repressed. Numerous studies have demonstrated that estrogens induced rapid and transient activation of the c-Src phosphorylation cascade. We found that ugonin K indeed raised the phosphorylated level of c-Src and such phosphorylation was significantly attenuated by ICI 182,780 treatment. Application of c-Src specific inhibitor PP2 concentration-dependently repressed ugonin K-induced osteogenesis. In the nuclear translocation assay, results showed that ugonin K increased the nuclear level of estrogen receptor-α protein, suggesting that an enhanced transcriptional activity might be observed. Excepting MC3T3-E1 cells, results obtained from ALP activity assay revealed that ugonin K also stimulated osteoblastic differentiation of human MG-63 osteosarcoma cells and rat primary osteoblasts isolated from femora. Our results demonstrate that ugonin K stimulated osteogenesis might act through an estrogen receptor-dependent activation of a non-classical signaling pathway mediated by phosphorylation of c-Src. Moreover, a transactivation potential toward estrogen receptor-α through a classical pathway might not be precluded.

• Authors: Chia-Hsin Lee, Yu-Ling Huang, Jyh-Fei Liao, Wen-Fei Chiou
• Journal: European journal of pharmacology (Eur J Pharmacol) Vol. 676 Issue 1-3 Pg. 26-33 (Feb 15 2012) ISSN: 1879-0712 [Electronic] Netherlands
• PMID: 22192930 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2011 Elsevier B.V. All rights reserved.

Chemical References

• Core Binding Factor Alpha 1 Subunit
• Estrogen Receptor alpha
• Flavonoids
• Receptors, Estrogen
• Sp7 Transcription Factor
• Sp7 protein, human
• Transcription Factors
• ugonin K
• Fulvestrant
• Estradiol
• Protein-Tyrosine Kinases
• CSK Tyrosine-Protein Kinase
• src-Family Kinases
• CSK protein, human
• Alkaline Phosphatase

Topics

• 3T3-L1 Cells
• Active Transport, Cell Nucleus (drug effects)
• Alkaline Phosphatase (metabolism)
• Animals
• CSK Tyrosine-Protein Kinase
• Calcification, Physiologic (drug effects)
• Cell Differentiation (drug effects)
• Cell Line, Tumor
• Cell Nucleus (drug effects, metabolism)
• Core Binding Factor Alpha 1 Subunit (genetics)
• Estradiol (analogs & derivatives, pharmacology)
• Estrogen Receptor alpha (metabolism)
• Flavonoids (pharmacology)
• Fulvestrant
• Humans
• Mice
• Organ Specificity
• Osteoblasts (cytology, drug effects)
• Osteogenesis (drug effects)
• Phosphorylation (drug effects)
• Protein-Tyrosine Kinases (metabolism)
• Receptors, Estrogen (metabolism)
• Signal Transduction (drug effects)
• Sp7 Transcription Factor
• Transcription Factors (genetics)
• Up-Regulation (drug effects)
• src-Family Kinases