Black soybean (Glycine max cv. Heugmi) seed coat extract suppresses TPA or UVB-induced COX-2 expression by blocking mitogen activated protein kinases pathway in mouse skin epithelial cells

Although previous studies have reported that black soybean has chemopreventive potential, the underlying mechanisms remain unclear. Upregulation of cyclooxygenase-2 (COX-2) has been known to be a key mediator in the development of skin cancer. The present study investigated the effect of black soybean (Glycine max cv. Heugmi) seed coat extract (BSE) on 12-O-tetradecanoylphorbol-13-acetate (TPA) or ultraviolet-B-(UVB)-induced COX-2 expression, and its underlying mechanisms. The TPA- or UVB-induced COX-2 expression in mouse skin epithelial cells were dose-dependently inhibited by BSE treatment. BSE suppressed the COX-2 promoter activity. BSE also attenuated the transactivation of activator protein-1 (AP-1) and nuclear factor (NF)-κB, transcription factors of COX-2 expression in mouse skin epithelial cells transfected stably with AP-1 and NF-κB luciferase promoter, respectively. Furthermore, BSE inhibited the activation of MAPKKs/MAPKs pathways that otherwise induced by TPA or UVB. Collectively, BSE suppresses TPA or UVB-induced COX-2 expression by blocking the expressions of MAPKKs/MAPKs pathways, which may contribute to its chemopreventive potential.