EXPRESSION OF THE FIBROBLAST GROWTH-FACTOR-4 (FGF-4) GENE IS REGULATED BY SERUM IN TERA-2 EMBRYONAL CARCINOMA-CELLS

Expression of the fibroblast growth factor 4 (FGF-4) gene is tightly r egulated during mammalian development. Dysregulation of FGF-4 gene exp ression results in cell transformation and tumorigenesis. It is theref ore pertinent to investigate the regulatory mechanisms which control e xpression of FGF-4. In an initial attempt to identify exogenous factor s other than retinoic acid which might control FGF-4 expression, we ha ve investigated the response of endogenous FGF-4 to serum in a number of embryonal carcinoma and embryonic stem cell lines. We have identifi ed a human embryonal carcinoma cell line (Tera-2) in which the FGF-4 g ene can be induced by serum. In Tera-2 cells made quiescent by serum d eprivation, expression of the FGF-4 gene is repressed. Subsequent addi tion of serum reactivates FGF-LC expression and further addition of cy cloheximide results in superinduction of mRNA suggesting that FGF-4 ma y be classified as an early response gene. It is suggested that this o bservation may be explained, at least in part, by the stage of differe ntiation of the Tera-2 cells.