Expression and regulation of mRNA coding for acidic and basic fibroblast growth factor and transforming growth factor...

We investigated the regulation of mRNAs coding for acidic fibroblast growth factor (aFGF), basic fibroblast growth factor (bFGF), and transforming growth factor-alpha (TGF alpha) in cultures of human neonatal foreskin fibroblasts, keratinocytes, and melanocytes. Each cell type was propagated in an optimized serum-free medium. In rapidly growing fibroblasts, the addition of fetal bovine serum caused a modest induction of aFGF message within 2 h in conjunction with a concomitant elevation of bFGF transcripts. In these same cells, TGF alpha mRNA could not be detected in any experimental condition. In contrast, keratinocytes rapidly growing in the presence of epidermal growth factor (EGF) contained transcripts for TGF alpha that increased substantially when these cells were treated with serum. This observation suggests that factors present in serum can elevate the levels of TGF alpha mRNA beyond the levels already present in keratinocyte cultures growing in the presence of EGF. These same keratinocyte cultures had low to undetectable levels of bFGF or aFGF message, and the levels of these mRNAs were not affected by serum treatment. Treatment of keratinocytes proliferating in the presence of EGF with TGF beta for 48 h caused expression of bFGF mRNA in four of six independent cell strains. TGF beta-enhanced expression of bFGF mRNA occurred as early as 12-24 h after TGF beta exposure. TGF beta did not enhance the expression of mRNA for aFGF or TGF alpha in keratinocytes. Melanocytes failed to express detectable levels of mRNA coding for any of these growth factors in the presence of absence of TGF beta or serum.(ABSTRACT TRUNCATED AT 250 WORDS)