Selective inactivity of TGF-β/decorin complexes

Previous studies had shown that binding of TGF-β to the small proteoglycan decorin results in its inactivation. Indeed, in osteosarcoma cells the addition of decorin prevented the TGF-β1-mediated up-regulation of biglycan synthesis. However, the down-regulation of proteoglycan-100 remained unaltered. Even in the presence of a 100,000-fold molar excess of decorin, TGF-β1 was fully active in U937 monocytes with respect to the inhibition of cell proliferation. There was no inhibition of the TGF-β-mediated stimulation of the retraction of fibroblast-populated collagen lattices. Thus, the formation of TGF-β/decorin complexes leads to the neutralization of distinct effects only.