(S)-[6]-Gingerol inhibits TGF-b-stimulated biglycan synthesis but not glycosaminoglycan hyperelongation in human vascular smooth muscle cells

Objectives (S)-[6]-Gingerol is under investigation for a variety of therapeutic uses. Transforming growth factor (TGF)-b stimulates proteoglycan synthesis, leading to increased binding of low-density lipoproteins, which is the initiating step in atherosclerosis.We evaluated the effects of (S)-[6]-gingerol on these TGFb- mediated proteoglycan changes to explore its potential as an anti-atherosclerotic agent. Methods Purified (S)-[6]-gingerol was assessed for its effects on proteoglycan synthesis by [35S]-sulfate incorporation into glycosaminoglycan chains and [35S]-Met/Cys incorporation into proteoglycans and total proteins in human vascular smooth muscle cells. Biglycan level was assessed by real-time quantitative polymerase chain reactions and the effects of (S)-[6]-gingerol on TGF-b signalling by assessment of the phosphorylation of Smads and Akt by western blotting. Key findings (S)-[6]-Gingerol concentration-dependently inhibited TGF-bstimulated proteoglycan core protein synthesis, and this was not secondary to inhibition of total protein synthesis. (S)-[6]-Gingerol inhibited biglycan mRNA expression. (S)-[6]-Gingerol did not inhibit TGF-b-stimulated glycosaminoglycan hyperelongation or phosphorylation of Smad 2, in either the carboxy terminal or linker region, or Akt phosphorylation. Conclusions The activity of (S)-[6]-gingerol to inhibit TGF-b-stimulated biglycan synthesis suggests a potential role for ginger in the prevention of atherosclerosis or other lipid-binding diseases. The signalling studies indicate a novel site of action of (S)-[6]-gingerol in inhibiting TGF-b responses.