Molecular and Cellular Biochemistry

, Volume 398, Issue 1–2, pp 105–113 | Cite as

EGFR-AKT-mTOR activation mediates epiregulin-induced pleiotropic functions in cultured osteoblasts

  • Jian-bo Fan
  • Wei Liu
  • Xin-hui Zhu
  • Kun Yuan
  • Da-wei Xu
  • Jia-jia Chen
  • Zhi-ming Cui


Epidermal growth factor (EGF) receptor (EGFR) emerges as an essential molecule for the regulating of osteoblast cellular functions. In the current study, we explored the effect of epiregulin, a new EGFR ligand, on osteoblast functions in vitro, and studied the underlying mechanisms. We found that epiregulin-induced EGFR activation in both primary osteoblasts and osteoblast-like MC3T3-E1 cells. Meanwhile, epiregulin activated AKT-mammalian target of rapamycin (mTOR) and Erk-mitogen-activated protein kinase (MAPK) signalings in cultured osteoblasts, which were blocked by EGFR inhibitor AG1478 or monoclonal antibody against EGFR (anti-EGFR). Further, in primary and MC3T3-E1 osteoblasts, epiregulin promoted cell proliferation and increased alkaline phosphatase activity, while inhibiting dexamethasone (Dex)-induced cell death. Such effects by epiregulin were largely inhibited by AG1478 or anti-EGFR. Notably, AKT-mTOR inhibitors, but not Erk inhibitors, alleviated epiregulin-induced above pleiotropic functions in osteoblasts. Meanwhile, siRNA depletion of Sin1, a key component of mTOR complex 2 (mTORC2), also suppressed epiregulin-exerted effects in MC3T3-E1 cells. Together, these results suggest that epiregulin-induced pleiotropic functions in cultured osteoblasts are mediated through EGFR-AKT-mTOR signalings.


Epiregulin EGFR AKT/mTOR signalings Osteoblasts 



Alkaline phosphatase


Epidermal growth factor




Mammalian target of rapamycin


Ribosomal S6 kinase 1



This work was generously supported by Grants from the National Natural Science Foundation of China.

Conflict of interests

The authors declare that they have no competing interests.

Supplementary material

11010_2014_2210_MOESM1_ESM.eps (695 kb)
Supplementary Fig. 1. MC3T3-E1 osteoblasts were pre-incubated with PD-98059 (1 μM) or U0126 (1 μM) for 1 h, followed by epiregulin (50 ng/ml) stimulation for 24 h, cell proliferation (cell counting assay, A) and ALP activity (B) were analyzed. For detecting cell death, above cells were co-incubated with Dex (1 μM, 24 h), trypan blue staining assay was performed (C). (EPS 695 kb)


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Copyright information

© Springer Science+Business Media New York 2014

Authors and Affiliations

  • Jian-bo Fan
    • 1
  • Wei Liu
    • 1
  • Xin-hui Zhu
    • 1
  • Kun Yuan
    • 1
  • Da-wei Xu
    • 1
  • Jia-jia Chen
    • 1
  • Zhi-ming Cui
    • 1
  1. 1.The Department of OrthopaedicsThe Second Affiliated Hospital of Nantong UniversityNantongPeople’s Republic of China

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