| Abstract: | The aim of the present study was to investigate which growth factors, receptors, and growth inhibiting factors are expressed in invasive breast cancer. Five (angiogenic) growth factors and their receptors: platelet-derived growth factor A chain (PDGF-AA) and PDGF receptor alpha (PDGFαR), PDGF-BB and PDGF beta receptor, transforming growth factor alpha (TGFα) and its receptor epidermal growth factor receptor (EGFR), and vascular endothelial growth factor (VEGF) and its receptors vascular endothelial growth factor receptor I (Flt-1) and vascular endothelial growth factor receptor II (Flk-1/KDR); two growth inhibiting factors: transforming growth factor beta-1 (TGFβ1) and TGFβ2) and their receptor couple transforming growth factor beta receptor I (TGFβR-I) and TGFβR-II; and basic fibroblast growth factor (bFGF) were stained by standard immunohistochemistry on frozen sections in 45 cases of invasive carcinoma of the breast. Staining was scored as negative or positive in tumour epithelium, stroma, and blood vessels. TGFβ1 and TGFβ2 were expressed in the tumour cells in 67 per cent and 76 per cent of cases, respectively, whereas PDGFβR and TGFβR-II were expressed in 0 per cent and 2 per cent, respectively. The other factors showed variable expression in tumour cells. All factors were expressed in the stroma in most cases, except Flt-1, Flk-1/KDR, TGFβ2, and TGFβR-II, which showed variable expression, and EGFR, which showed no expression. The endothelium was in most cases positive for bFGF, PDGF-AA, PDGF-BB, VEGF, PDGFαR, PDGFβR, and TGFβ1 but TGFβ2 was negative in most cases and TGFα, EGFR, Flt-1, Flk-1/KDR, TGFβR-I, and TGFβR-II were variably expressed. The most interesting possible auto/paracrine loops, as demonstrated on serial sections and by fluorescence double staining, were the TGFα/EGFR, TGFβs/TGFβR, VEGF/Flt-1, and the VEGF/Flk-1 combinations. In conclusion, growth factors, growth inhibiting factors, and their receptors are frequently expressed in invasive breast cancer. Indications for some possible auto-and paracrine loops have been found, which should encourage further study on the role of these factors in breast cancer proliferation and angiogenesis. © 1998 John Wiley & Sons, Ltd. |
