β-Lapachone Regulates the Transforming Growth Factor-β–Smad Signaling Pathway Associated with Collagen Biosynthesis in Human Dermal Fibroblasts

The transforming growth factor (TGF)-β–Smad signaling pathway regulates collagen biosynthesis in human dermal fibroblasts. We found that β-lapachone stimulated type I collagen expression in human dermal fibroblasts. In this study, we evaluated whether the β-lapachone-induced upregulation of collagen biosynthesis in human dermal fibroblasts is associated with the TGF-β–Smad signaling pathway. In cultured human dermal fibroblasts, both Smad 2 and Smad 3 (Smad 2/3) were phosphorylated by β-lapachone treatment in a concentration-dependent manner. SB431542, a specific inhibitor of TGF-β receptor I kinase, inhibited the β-lapachone-mediated Smad 2/3 phosphorylation and type I collagen expression, suggesting that β-lapachone stimulates collagen production via the TGF-β receptor I kinase-dependent pathway. β-Lapachone did not increase TGF-β1 synthesis in human dermal fibroblasts, suggesting that the molecular mechanism of β-lapachone for the upregulation of collagen synthesis is due to the extracellular regulation of availability and activities of TGF-β. This study provides new insights into the role of β-lapachone in collagen synthesis in human dermal fibroblasts and suggests that β-lapachone can be used as a pharmacological tool to study collagen homeostasis associated with TGF-β–Smad signaling.