Department of Biochemistry and Molecular Biology, Faculty of Basic Medicine, Second Military Medical University, Shanghai, China.
Cell Death Dis. 2013 Jun 6;4(6):e657. doi: 10.1038/cddis.2013.182.
Hepatocellular carcinoma (HCC) is generally acknowledged as the most common primary malignant tumor, and it is known to be resistant to conventional chemotherapy. Wentilactone B (WB), a tetranorditerpenoid derivative extracted from the marine algae-derived endophytic fungus Aspergillus wentii EN-48, has been shown to trigger apoptosis and inhibit metastasis in HCC cell lines. However, the mechanisms of its antitumor activity remain to be elucidated. We report here that WB could significantly induce cell cycle arrest at G2 phase and mitochondrial-related apoptosis, accompanying the accumulation of reactive oxygen species (ROS). Additionally, treatment with WB induced phosphorylation of extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), but not p38 MAP kinase. Among the pathway inhibitors examined, only SP600125 (JNK inhibitor) markedly reversedWB-induced apoptosis, and only U0126 (ERK inhibitor) significantly blocked WB-triggered G2 phase arrest. We also found that WB treatment increased both Ras and Raf activation, and transfection of cells with dominant-negative Ras (RasN17) abolishedWB-induced apoptosis and G2 phase arrest in SMMC-7721 cells. Furthermore, the results of inverse docking (INVDOCK) analysis suggested that WB could bind to Ras-GTP, and the direct binding affinity was also confirmed by surface plasmon resonance (SPR). Finally, in vivo, WB suppressed tumor growth in mouse xenograft models. Taken together, these results indicate that WB induced G2/M phase arrest and apoptosis in human hepatoma SMMC-7721 cells via the Ras/Raf/ERK and Ras/Raf/JNK signaling pathways, and this agent may be a potentially useful compound for developing anticancer agents for HCC.
肝细胞癌（HCC）通常被认为是最常见的原发性恶性肿瘤，并且已知对常规化疗具有抗性。Wentilactone B（WB）是一种从海洋藻类衍生的内生真菌 Aspergillus wentii EN-48 中提取的四环二萜衍生物，已被证明可在 HCC 细胞系中触发细胞凋亡并抑制转移。然而，其抗肿瘤活性的机制仍有待阐明。我们在这里报告 WB 可显著诱导细胞周期停滞在 G2 期和线粒体相关的细胞凋亡，同时伴随着活性氧（ROS）的积累。此外，WB 处理诱导细胞外信号调节激酶（ERK）、c-Jun N 端激酶（JNK）的磷酸化，但不诱导 p38 MAP 激酶的磷酸化。在检查的途径抑制剂中，只有 SP600125（JNK 抑制剂）显著逆转了 WB 诱导的细胞凋亡，只有 U0126（ERK 抑制剂）显著阻断了 WB 触发的 G2 期阻滞。我们还发现 WB 处理增加了 Ras 和 Raf 的激活，并且转染细胞中的显性负 Ras（RasN17）消除了 WB 诱导的 SMMC-7721 细胞中的细胞凋亡和 G2 期阻滞。此外，反向对接（INVDOCK）分析的结果表明 WB 可以与 Ras-GTP 结合，并且表面等离子体共振（SPR）也证实了直接结合亲和力。最后，在体内，WB 抑制了小鼠异种移植模型中的肿瘤生长。总之，这些结果表明 WB 通过 Ras/Raf/ERK 和 Ras/Raf/JNK 信号通路诱导人肝癌 SMMC-7721 细胞的 G2/M 期阻滞和细胞凋亡，并且该药物可能是开发用于 HCC 的抗癌药物的潜在有用化合物。
