Production and auto-induction of transforming growth factor-alpha in human keratinocytes.
Transforming growth factor-alpha (TGF-alpha) is a polypeptide which is structurally related to epidermal growth factor (EGF) and binds to the EGF receptor. TGF-alpha synthesis occurs in a variety of neoplastic cells and during early fetal development but has not been reported in normal cells of the adult organisms. TGF-alpha has therefore been regarded as an embryonic growth factor which is inappropriately expressed during neoplasia. Here we report that primary cultures of normal human keratinocytes synthesize TGF-alpha. Furthermore, we show that addition of EGF or TGF-alpha to these cultures induces TGF-alpha gene expression, suggesting that a mechanism of auto-induction exists. Analysis of normal skin biopsies using in situ hybridization and immunohistochemistry demonstrates the in vivo presence of TGF-alpha messenger RNA and protein in the stratified epidermis.
D002478:Cells, Cultured; D004815:Epidermal Growth Factor / Q000494:pharmacology; D004817:Epidermis / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006133:Growth Substances; D006801:Humans; D007633:Keratins / Q000378:metabolism*; D008544:Melanocytes / Q000378:metabolism; D009363:Neoplasm Proteins; D009693:Nucleic Acid Hybridization; D010452:Peptide Biosynthesis; D010455:Peptides / Q000235:genetics / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D015291:Transforming Growth Factors
D006133:Growth Substances; D009363:Neoplasm Proteins; D010455:Peptides; D012333:RNA, Messenger; D004815:Epidermal Growth Factor; D007633:Keratins; D015291:Transforming Growth Factors