Copper stimulates human oral fibroblasts in vitro: a role in the pathogenesis of oral submucous fibrosis

Copper is implicated in the pathogenesis of several fibrotic disorders. Areca nut has been shown to have a high copper content and areca chewing is associated with oral submucous fibrosis (OSF). The effects of copper on human oral fibroblasts were investigated in vitro. Human oral fibroblasts were incubated with copper chloride (CuCl2) at concentrations ranging from 0.01 microM to 500 microM for 24 h, and in vitro cell proliferation was assayed by incorporation of tritiated-thymidine; soluble and non-soluble collagen synthesis was assayed using tritiated-proline. Addition of copper chloride at concentrations ranging from 0.1 microM to 50 microM increased the collagen synthesis by the oral fibroblasts compared with growth without copper (P<0.05). The addition of copper chloride neither increased the synthesis of non-collagenous proteins by the fibroblasts nor influenced their proliferation rate. We conclude that copper upregulates collagen production in oral fibroblasts. This appears to be concentration dependent, with peak collagen synthesis at 50 microM CuCl2. These in vitro results taken together with the recent findings of copper in oral biopsies from OSF subjects support the hypothesis that copper in areca nut acts as a mediator of OSF.