Juglone (JG), a naturally-occurring naphthoquinone of Manchurian walnut (Juglans mandshurica) was shown to inhibit proliferation in various tumor types. However, the molecular mechanisms of JG on the induction of apoptosis and autophagy in HepG2 cells have not been examined. Herein, we investigated that JG could inhibit cell proliferation by induction of G2/M phase arrest. Also, occurrence of apoptosis was closely related with loss of mitochondrial membrane potential, the changes of apoptosis-related proteins after treatment with JG. In addition, we found that JG caused autophagy, as evidenced by increased expressions of LC3-II and Beclin-1. Interestingly, inhibition of JG-induced autophagy by 3-methyladenine (3-MA) and wortmannin (WT) significantly decreased apoptosis, whereas the apoptosis inhibitor z-VAD-fmk slightly enhanced autophagy. Furthermore, the induction of autophagy and apoptosis was associated with activation of MAPK family members (p38 and JNK) and production of reactive oxygen species (ROS). Both JNK inhibitor (SP600125) and ROS scavenger (N-acetylcysteine, NAC) could attenuate JG-induced autophagy and apoptosis. However, the p38-specific inhibitor SB203580 enhanced autophagic and apoptotic death. Moreover, the ROS scavenger NAC prevented phosphorylation of both p38 and JNK. Collectively, our data revealed that JG induced G2/M phase arrest, apoptosis, and autophagy through the ROS-dependent signaling pathway.

Juglone（JG），一种满州核桃的天然萘醌（Juglans mandshurica已显示）可以抑制各种肿瘤类型的增殖。但是，尚未研究JG诱导HepG2细胞凋亡和自噬的分子机制。在本文中，我们研究了JG可以通过诱导G2 / M期阻滞来抑制细胞增殖。另外，JG处理后细胞凋亡的发生与线粒体膜电位的丧失，细胞凋亡相关蛋白的变化密切相关。此外，我们发现JG引起自噬，如LC3-II和Beclin-1表达增加所证明。有趣的是，3-甲基腺嘌呤（3-MA）和渥曼青霉素（WT）抑制JG诱导的自噬明显降低了细胞凋亡，而凋亡抑制剂z-VAD-fmk则略微增强了自噬。此外，自噬和细胞凋亡的诱导与MAPK家族成员（p38和JNK）的活化和活性氧（ROS）的产生有关。JNK抑制剂（SP600125）和ROS清除剂（N-乙酰半胱氨酸，NAC）均可减弱JG诱导的自噬和细胞凋亡。但是，p38特异性抑制剂SB203580增强了自噬和凋亡的死亡。此外，ROS清除剂NAC阻止了p38和JNK的磷酸化。总体而言，我们的数据显示JG通过ROS依赖性信号传导途径诱导G2 / M期阻滞，凋亡和自噬。p38特异性抑制剂SB203580可增强自噬和凋亡死亡。此外，ROS清除剂NAC阻止了p38和JNK的磷酸化。总体而言，我们的数据显示JG通过ROS依赖性信号传导途径诱导G2 / M期阻滞，凋亡和自噬。p38特异性抑制剂SB203580可增强自噬和凋亡死亡。此外，ROS清除剂NAC阻止了p38和JNK的磷酸化。总体而言，我们的数据显示JG通过ROS依赖性信号传导途径诱导G2 / M期阻滞，凋亡和自噬。