A novel adamantyl benzylbenzamide derivative, AP736, inhibits melanogenesis in B16F10 mouse melanoma cells via glycogen synthase kinase 3β phosphorylation

Abstract

Recently, much effort has been made to develop effective dermatological depigmenting compounds. In this study, we investigated the novel candidate compound, AP736 (an adamantyl benzylbenzamide derivative), and its effects on melanogenesis in B16F10 melanoma cells, as well as the mechanisms involved. AP736 has been reported to exert anti-melanogenic effects in melanocytes in vitro and in artificial skin equivalents through the inhibition of key melanogenic enzymes and the suppression of the cAMP-protein kinase A (PKA)-cAMP response element‑binding protein (CREB) signaling pathway. Thus, we examined another pathway of melanogenesis involving the effects of AP736 on the glycogen synthesis kinase 3β (GSK3β) pathway. Melanin content and tyrosinase activity were measured using a spectrophotometer after the cells were treated with AP736. The AP736-induced activation of signaling pathways was examined by western blot analysis. We confirmed that AP736 decreased melanin production in a dose-dependent manner; however, it did not directly inhibit tyrosinase, the rate-limiting melanogenic enzyme. The expression of microphthalmia-associated transcription factor, tyrosinase, and related signal transduction pathways was also investigated. The Wnt signaling pathway is deeply involved in melanogenesis; therefore, phosphorylation by GSK3β was assessed following treatment with AP736. AP736 induced GSK3β phosphorylation (inactivation), but it did not alter the level of β-catenin. Furthermore, the expression of α-melanocyte-stimulating hormone-induced tyrosinase was downregulated by AP736. Our data suggest that AP736 exerts hypopigmentary effects through the downregulation of tyrosinase via GSK3β phosphorylation.

Pyruvic acid/ethyl pyruvate inhibits melanogenesis in B16F10 melanoma cells through PI3K/AKT, GSK3β, and ROS‐ERK signaling pathways

“…PI3K activates AKT, which then inhibits GSK3β through phosphorylation at Ser9 (Cross, Alessi, Cohen, Andjelkovich, & Hemmings, ). Recent studies have shown that GSK3β regulates MITF activity (Shin et al, ) but the detailed mechanisms remain unclear. To determine the contribution of PI3K/AKT and GSK3β signaling to melanogenesis, we treated B16F10 cells with the PI3K inhibitor LY294002 and GSK3β inhibitor (2Z,3E)‐6‐bromoindirubin‐3'‐oxime (BIO).…”

“…MITF gene expression is regulated by many factors, including CREB, PI3K/AKT (Chae et al, ; Hwang et al, ), GSK3β (Shin et al, ), and MAPK (ERK, c‐Jun N‐terminal kinase, and p38; Peng et al, ). In our study, ERK phosphorylation was increased by PA and EP treatment, which corresponded to a decrease in MITF protein level and an increase in ROS generation.…”

“…In addition to the PKA/CREB signaling pathway, MITF expression and activity are regulated by extracellular signal‐regulated kinase (ERK), a mitogen‐activated protein kinase (MAPK) family member (Peng, Lin, Wang, Shih, & Chou, ) that phosphorylates MITF at S73 and targets the protein for degradation by the proteasome (Lee, Lee, Chang, & Lee, ; Wu, Lin, Yang, Weng, & Tsai, ). Phosphoinositide 3‐kinase (PI3K)/AKT (Chae et al, ; Hwang et al, ) and glycogen synthase kinase 3 beta (GSK3β; Shin et al, ) also negatively regulate MITF activity and thereby suppress melanogenesis.…”

Inhibitory effects of Stichopus japonicus extract on melanogenesis of mouse cells via ERK phosphorylation

“…A mushroom TYR activity assay was assessed by measuring DOPA oxidase activity using a slightly modified experimental protocol from a previous study ( 21 ). Briefly, 95 µl of 0.1 M sodium phosphate buffer (pH 6.5) containing the indicated concentrations of kojic acid (50 µM) and MSCE, and 20 µl of mushroom TYR (1,000 U/ml) were combined in each well, and 20 µl of 5 mM l-DOPA was then added.…”

An Isoxazole Chalcone Derivative Enhances Melanogenesis in B16 Melanoma Cells via the Akt/GSK3β/β-Catenin Signaling Pathways

“…On the contrary, when the Wnt pathway is activated by the interactions of Wnt 1, Wnt3a, and Wnt8 with frizzled receptors and low-density lipoprotein receptor-related protein (Lrp) 5/6 co-receptors [ 13 ], GSK3β is negatively regulated. Thereafter, cytoplasmic β-catenin will translocate into the nucleus and bind to the promoter of MITF together with LEF1, resulting in the transcriptional activation of MITF [ 14 , 15 , 16 ]. Another signaling pathway involved in melanogenesis regulation is phosphatidylinositol-3-kinase (PI3K)/Akt signaling.…”