Title:HSP70 Inhibitors Reduce The Osteoblast Migration By Epidermal Growth Factor
Volume: 18
Issue: 7
Author(s): Tetsu Kawabata, Takanobu Otsuka, Kazuhiko Fujita, Go Sakai, Woo Kim, Rie Matsushima-Nishiwaki, Gen Kuroyanagi, Osamu Kozawa* Haruhiko Tokuda
Affiliation:
- Department of Pharmacology, Gifu University Graduate School of Medicine, Gifu,Japan
Keywords:
HSP70, EGF, migration, p44/p42 MAP kinase, Akt, osteoblast.
Abstract: Background: We have recently reported that epidermal growth factor (EGF)
induces migration of osteoblast-like MC3T3-E1 cells through the activation of p44/p42
mitogen-activated protein (MAP) kinase, p38 MAP kinase, stress-activated protein
kinase/ c-Jun N-terminal kinase (SAPK/JNK) and Akt. Furthermore, we demonstrated
that heat shock protein 70 (HSP70) down-regulates the transforming growth factor-β-
stimulated vascular endothelial growth factor synthesis via suppression of p38 MAP
kinase in osteoblast-like MC3T3-E1 cells. However, the exact role of HSP70 underlying
osteoblast migration is not fully elucidated.
Objective: The aim of this study is to investigate the effects of HSP70 inhibitors on the
EGF-stimulated osteoblast migration, and the underlying mechanism.
Methods: Osteoblast-like MC3T3-E1 cells were treated with two types of HSP70
inhibitors, VER-155008 or YM-08. Transwell cell migration assay and wound-healing
assay were analyzed for osteoblast migration. The expression levels of HSP70 and the
phosphorylation of p38 MAP kinase, p44/p42 MAP kinase, SAPK/JNK or Akt were
evaluated by a Western blot analysis.
Results: EGF hardly affected the expression levels of HSP70 at the present or absent
of VER-155008. EGF-stimulated migration was significantly reduced by both HSP70
inhibitors, VER-155008 and YM-08, determined by a transwell cell migration assay. The
suppressive effects of both HSP70 inhibitors on the migration stimulated by EGF were
also observed by a wound-healing assay. VER-155008 inhibited the EGF-induced
phosphorylation of p44/p42 MAP kinase and AKT, but not p38 MAP kinase or
SAPK/JNK.
Conclusion: This study provides new evidence that HSP70 inhibitors reduce the EGFstimulated
migration of osteoblasts through the suppression of p44/p42 MAP kinase and
Akt.
