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Transforming growth factor β modulates proliferation of osteoblastic cells: Relation to its effect on receptor levels for epidermal growth factor
Author(s) -
Uneno Susumu,
Yamamoto Itsuo,
Yamamuro Takao,
Okumura Hideo,
Ohta Shuichi,
Lee Kaechoong,
Kasai Ryuichi,
Konishi Junji
Publication year - 1989
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1002/jbmr.5650040206
Subject(s) - epidermal growth factor , transforming growth factor , endocrinology , tgf alpha , medicine , epidermal growth factor receptor , growth factor , growth factor receptor inhibitor , receptor , chemistry , cell growth , microbiology and biotechnology , cancer research , biology , biochemistry
The effect of transforming growth factor β (TGF‐β) on cellular proliferation of osteoblastic MC3T3‐E1 cells was studied with particular emphasis on its effect on modulation of epidermal growth factor (EGF) receptors. In other cells, TGF‐β has been reported to augment EGF receptors. Exposure of MC3T3‐E1 cells to TGF‐β initially increased cell surface EGF receptor levels and decreased the rate of DNA synthesis. The initial elevation of EGF receptor levels was due to increased receptor number per cell, not to changes in binding affinity. On the contrary, prolonged exposure (longer than 40 h) resulted in a decrease in EGF receptor and an increase in the rate of DNA synthesis. Thus, the effects of TGF‐β on these cells appears to be biphasic, reflecting complex mechanisms of action; the early effects of TGF‐β may be consistent with cellular differentiation to the osteoblastic phenotype with decreased cellular proliferation, whereas chronic exposure of these cells to TGF‐β stimulated cellular proliferation and inhibited osteoblastic phenotype expression. It is not likely that stimulation of cellular proliferation was through elevation of EGF receptor levels, because TGF‐β did not enhance the stimulatory effect of EGF on cellular proliferation. Thus, we conclude that TGF‐β possesses a stimulatory effect on the cellular proliferation of osteoblastic MC3T3‐E1 cells independent of its modulative effect on EGF receptor level.