title: Possible positive autocrine feedback in the prereplicative phase of human fibroblasts.
abstract: The growth of normal diploid fibroblasts is generally thought to be tightly controlled by exogenous growth factors such as platelet-derived growth factor (PDGF) and epidermal growth factor (EGF). Subversion of a growth factor pathway at a regulatory point is considered to be a key event in neoplastic transformation and tumorigenesis. Thus, simian sarcoma virus has acquired the gene encoding the B-chain of PDGF and there is direct experimental proof that SSV-transformation is mediated by a PDGF-like growth factor. There is accumulating evidence that PDGF-like molecules are also synthesized and released by certain normal cells, suggesting an important role of cellularly produced PDGF in development and tissue regeneration. We now present evidence that a transient expression of the gene encoding the PDGF A-chain, and the synthesis and release of functional A-chain homodimers, is an early event in the prereplicative phase of normal human foreskin fibroblasts exposed to PDGF or EGF. Since these cells are PDGF-responsive, the results imply the existence of a positive autocrine signal that may serve as an amplifier of the mitogenic response under certain conditions.
mesh_terms: D002455:Cell Division / Q000187:drug effects; D003513:Cycloheximide / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology* / Q000187:drug effects; D006801:Humans; D007370:Interferon Type I / Q000235:genetics; D008970:Molecular Weight; D010982:Platelet-Derived Growth Factor / Q000235:genetics* / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: D007370:Interferon Type I; D010982:Platelet-Derived Growth Factor; D012333:RNA, Messenger; D004815:Epidermal Growth Factor; D003513:Cycloheximide