Attenuation by HSP90 inhibitors of EGF-elicited migration of osteoblasts: involvement of p44/p42 MAP kinase

ABSTRACT

Background

We have demonstrated that epidermal growth factor (EGF)-induced migration of osteoblast-like MC3T3-E1 cells is mediated through p44/p42 mitogen-activated protein (MAP) kinase, p38 MAP kinase, stress-activated protein kinase/ c-Jun N-terminal kinase (SAPK/JNK), and Akt.The molecular chaperone heat shock protein 90 (HSP90) is abundantly expressed in osteoblasts. However, the role of HSP90 in osteoblast migration remains obscure.

Objective

In this study, we investigated the effect of HSP90 inhibitors on the EGF-induced migration of MC3T3-E1 cells and the mechanism.

Methods

Clonal osteoblast-like MC3T3-E1 cells were treated with the HSP90 inhibitors geldanamycin or onalespib and then stimulated with EGF. Cell migration was evaluated using the transwell cell migration assay and wound-healing assay. The viability of MC3T3-E1 cells was analyzed using the Cell Counting Kit-8. The phosphorylation of p44/p42 MAP kinase, p38 MAP kinase, SAPK/JNK, Akt, and protein kinase-like endoplasmic reticulum kinase (PERK) was evaluated by western blot analysis.

Results

EGF-induced migration was significantly suppressed by geldanamycin and onalespib, evaluated by both transwell cell migration assay and wound-healing assay. Geldanamycin and onalespib did not significantly alter cell viability. Geldanamycin and onalespib markedly reduced the EGF-induced phosphorylation of p44/p42 MAP kinase, but not p38 MAP kinase or Akt. By contrast, geldanamycin and onalespib increased the EGF-induced phosphorylation of SAPK/JNK. PERK phosphorylation was not significantly affected by geldanamycin or onalespib.

Conclusion

Our results strongly suggest that HSP90 inhibitors reduce the EGF-induced osteoblast migration through the p44/p42 MAP kinase.

KEYWORDS:

• Osteoblast
• migration
• HSP90 inhibitor
• EGF
• p44/p42 MAP kinase

Acknowledgments

We are very grateful to Mrs. Yumiko Kurokawa for her skillful technical assistance. The current investigation was supported in part by Grants-in-Aid for Scientific Research (15K10487, 17K11002 and 19K18471) from the Ministry of Education, Culture, Science, Sports and Technology of Japan, and Research Funding for Longevity Sciences (28-9 and 29-12) from National Center for Geriatrics and Gerontology, Japan.

Disclosure of potential conflicts of interest

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Center for Geriatrics and Gerontology [28-9, 29-12]; Ministry of Education, Culture, Science, Sports and Technology of Japan [15K10487, 17K11002, 19K18471].