Effects of transforming growth factor-B1 and tumour necrosis factor-A on cultured fibroblasts from skin fibroma as modulated by toremifene

To determine how toremifene, an anti-oestrogen triphenylethylene derivate, reduces tumour mass, we investigated its modulation of TGF-β1 and TNF-α in fibroma fibroblasts. Normal and fibroma fibroblasts, isolated from patients affected by Gardner's syndrome without or with fibroma manifestation, were cultured in vitro. Secretion of GAG, collagen and TGF-β1 was increased in fibroma fibroblasts compared to healthy cells. The increase in TGF-β1 secretion into the medium was associated with a parallel increase in TGF-β1 gene expression and receptor number. Receptor cross-linking studies using radiolabelled TGF-β1 revealed more receptors, particularly types I and II, in fibroma fibroblasts than in normal cells. Normal and fibroma fibroblasts did not synthesise TNF-α, but they had TNF-α membrane receptors, as shown by TNF-α assay. TNF-α secreted by human monocytes, which may be present in the peritumoral area, increased cell proliferation and GAG accumulation and was, in turn, enhanced by TGF-β1 treatment. Both growth factors increased angiogenesis, as shown by the CAM assay. Toremifene reduced TGF-β1 secretion by fibroma fibroblasts and TNF-α secretion by monocytes, thus downregulating cell proliferation, ECM macromolecule accumulation and angiogenic progression. We hypothesise that increased TGF-β1 gene expression and TGF-β1 secretion in fibroma fibroblasts as well as the subsequent rise in TNF-α production by monocytes may facilitate fibroma growth and that toremifene inhibits autocrine and paracrine growth factor production.