title: Platelet-derived growth factor-BB controls epithelial tumor phenotype by differential growth factor regulation in stromal cells.
abstract: Platelet-derived growth factor (PDGF) stimulates tumor growth and progression by affecting tumor and stromal cells. In the HaCaT skin carcinogenesis model, transfection of immortal nontumorigenic and PDGF-receptor-negative HaCaT keratinocytes with PDGF-B induced formation of benign tumors. Here, we present potential mechanisms underlying this tumorigenic conversion. In vivo, persistent PDGF-B expression induced enhanced tumor cell proliferation but only transiently stimulated stromal cell proliferation and angiogenesis. In vitro and in vivo studies identified fibroblasts as PDGF target cells essential for mediating transient angiogenesis and persistent epithelial hyperproliferation. In fibroblast cultures, long-term PDGF-BB treatment caused an initial up-regulation of vascular endothelial growth factor (VEGF)-A, followed by a drastic VEGF down-regulation and myofibroblast differentiation. Accordingly, in HaCaT/PDGF-B transplants, initially enhanced VEGF expression by stromal fibroblasts was subsequently reduced, followed by down-regulation of angiogenesis, myofibroblast accumulation, and vessel maturation. The PDGF-induced, persistently increased expression of the hepatocyte growth factor by fibroblasts in vitro and in vivo was most probably responsible for enhanced epithelial cell proliferation and benign tumor formation. Thus, by paracrine stimulation of the stroma, PDGF-BB induced epithelial hyperproliferation, thereby promoting tumorigenicity, whereas the time-limited activation of the stroma followed by stromal maturation provides a possible explanation for the benign tumor phenotype.
authors.affiliation: Tumor and Microenvironment Group, German Cancer Research Center, Heidelberg, Germany.
authors.forename: Wiltrud
authors.initials: W
authors.lastname: Lederle
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Stark
authors.forename: Mihaela
authors.initials: M
authors.lastname: Skobe
authors.forename: Norbert E
authors.initials: NE
authors.lastname: Fusenig
authors.forename: Margareta M
authors.initials: MM
authors.lastname: Mueller
mesh_terms: D000199:Actins / Q000378:metabolism; D000077214:Becaplermin; D049109:Cell Proliferation / Q000187:drug effects; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D043169:Endostatins / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects* / Q000473:pathology*; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects; D006133:Growth Substances / Q000494:pharmacology*; D017228:Hepatocyte Growth Factor / Q000494:pharmacology; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000473:pathology; D008648:Mesoderm / Q000166:cytology; D009369:Neoplasms / Q000473:pathology*; D018919:Neovascularization, Physiologic / Q000187:drug effects; D019899:Paracrine Communication / Q000187:drug effects; D010641:Phenotype; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D020574:Proto-Oncogene Proteins c-sis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017479:Receptors, Platelet-Derived Growth Factor / Q000378:metabolism; D017154:Stromal Cells / Q000166:cytology / Q000187:drug effects* / Q000473:pathology; D013997:Time Factors; D014162:Transfection; D015854:Up-Regulation / Q000187:drug effects; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis / Q000235:genetics
chemical_list: D000199:Actins; D043169:Endostatins; D006133:Growth Substances; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; D000077214:Becaplermin; D017228:Hepatocyte Growth Factor; D017479:Receptors, Platelet-Derived Growth Factor