The synergistic effect of TGF-beta and 1,25-dihydroxyvitamin D3 on SPARC synthesis and alkaline phosphatase activity in human pulp fibroblasts.

1,25(OH)2D3 and TGF-beta can influence the function and differentiation of dental pulp fibroblasts. In this study, we examined the effect of 1,25(OH)2D3 and TGF-beta on the synthesis of SPARC and ALP activity in human pulp fibroblasts. Two isoforms of SPARC, the 43 and 38 kDa, were detected in this cell type. TGF-beta increased the synthesis of SPARC about 2.5-fold after 3 days of treatment but had no effect on the ALP activity. On the contrary, 1,25(OH)2D3 increased ALP activity 2-fold but had no effect on SPARC. The combination of TGF-beta and 1,25(OH)2D3 significantly induced SPARC synthesis and ALP activity by 5 and 9 folds, respectively (P<0.05). This finding suggested the synergistic effect between TGF-beta and 1,25(OH)2D3 in dental pulp fibroblasts on the synthesis of SPARC and ALP activity. This interaction could influence the function and differentiation of dental pulp fibroblasts.