Department of Biological Sciences, College of Natural Sciences, Kongju National University, Gongju, Chungcheongnam‑do 32588, Republic of Korea.
Int J Oncol. 2020 Jan;56(1):379-389. doi: 10.3892/ijo.2019.4930. Epub 2019 Dec 2.
Thymoquinone (TQ) is a component found in the seeds of Nigella sativa, an annual plant growing on the Mediterranean coast, and is known for its anticancer and anti‑inflammatory effects. However, to date, at least to the best of our knowledge, limited studies are available examining the molecular mechanisms through which TQ inhibits melanogenesis. Accordingly, this study aimed to treat B16F10 mouse melanoma cells with TQ to investigate its apparent effects and its molecular regulatory mechanisms. Treatment of the B16F10 cells with 10, 15 and 20 µM of TQ for 48 h resulted in a dose‑dependent decrease in the expression of microphthalmia‑associated transcription factor (MITF), tyrosinase expression and tyrosinase activity, and these treatments simultaneously led to a decrease in the protein expression and transcription of β‑catenin, a Wnt signaling pathway protein. Pre‑treatment of the cells with the proteasome inhibitor, MG132, to confirm the inhibition of melanogenesis through the β‑catenin pathway by TQ treatment resulted in an increase in the expression of β‑catenin that was initially reduced by TQ, and the expression and activity of MITF and tyrosinase also increased. Pre‑treatment with LiCl, which is known to inactivate glycogen synthase kinase 3β (GSK3β) by inducing the phosphorylation of the Ser‑9 site, resulted in an increased phospho‑GSK3β expression accompanied by β‑catenin that was initially reduced by TQ, and the recovery of the expression and activity of tyrosinase was also confirmed. The transfection of S37A cDNA into B16F10 cells that overexpress β‑catenin resulted in the recovery of β‑catenin expression that was initially reduced by TQ, and this treatment also recovered the expression and activity of tyrosinase. When zebrafish eggs were treated with 1, 2.5 and 5 µM of TQ at 10 h following fertilization, their melanin content decreased in a dose‑dependent manner. On the whole, these findings demonstrated that the inhibition of melanogenesis in B16F10 mouse melanoma cells by TQ treatment resulted from the inhibition of the β‑catenin pathway and confirmed that TQ treatment inhibited melanogenesis in zebrafish.
姜酮（TQ）是一种在黑种草种子中发现的成分，黑种草是一种在地中海沿岸生长的一年生植物，以其抗癌和抗炎作用而闻名。然而，到目前为止，据我们所知，研究 TQ 抑制黑色素生成的分子机制的研究有限。因此，本研究旨在用 TQ 治疗 B16F10 小鼠黑色素瘤细胞，以研究其明显的作用及其分子调节机制。用 10、15 和 20 μM 的 TQ 处理 B16F10 细胞 48 h 导致小眼畸形相关转录因子（MITF）、酪氨酸酶表达和酪氨酸酶活性的剂量依赖性降低，这些处理同时导致 Wnt 信号通路蛋白β-连环蛋白（β-catenin）的蛋白表达和转录降低。用蛋白酶体抑制剂 MG132 预处理细胞，以证实 TQ 处理通过 β-catenin 途径抑制黑色素生成，导致 TQ 最初降低的 β-catenin 表达增加，MITF 和酪氨酸酶的表达和活性也增加。用氯化锂（LiCl）预处理，LiCl 通过诱导 Ser-9 位点磷酸化使糖原合成激酶 3β（GSK3β）失活，导致 TQ 最初降低的磷酸化 GSK3β表达增加，同时也证实了酪氨酸酶的表达和活性恢复。将 S37A cDNA 转染到过度表达β-catenin 的 B16F10 细胞中，导致 TQ 最初降低的β-catenin 表达恢复，这种处理也恢复了酪氨酸酶的表达和活性。用 1、2.5 和 5 μM 的 TQ 处理受精后 10 h 的斑马鱼卵，其黑色素含量呈剂量依赖性降低。总的来说，这些发现表明 TQ 处理抑制 B16F10 小鼠黑色素瘤细胞中的黑色素生成是由于抑制了β-catenin 途径，并证实 TQ 处理抑制了斑马鱼的黑色素生成。
