Retinoic Acid Differentially Affects Platelet-derived Growth Fador and Epidermal Growth Factor- regulated Cell Growth of Mouse

Retinoic acid (RA) plays an important role in the control of cell growth and differentiation. To elucidate the effects of RA for osteoblasts, we examined here the responsiveness of normal osteoblast-like MC3T3-E1 cells treated with LA for two growth factors, platelet-derived growth factor (PDGF) and epidermal growth factor (EGF). The transcripts of a- and y-RA receptors were constitutively expressed in MC3T3-E1 cells, and the expression of the 13-RA receptor mRNA was induced by RA. The PDGF-induced mitogenicity of MC3T3-E1 cells was significantly enhanced by 1 M RA pretreatment, whereas the EGF-induced mitogenicity was suppressed by the same treatment. The expression of both a- and 3-PDGF receptor gene products detecte