Aspafilioside B induces G2/M cell cycle arrest and apoptosis by up-regulating H-Ras and N-Ras via ERK and p38 MAPK signaling pathways in human hepatoma HepG2 cells

• Published in: Molecular carcinogenesis Vol. 55; no. 5; pp. 440 - 457
• Main Authors: Liu, Wei, Ning, Rui, Chen, Rui-Ni, Huang, Xue-Feng, Dai, Qin-Sheng, Hu, Jin-Hua, Wang, Yu-Wen, Wu, Li-Li, Xiong, Jing, Hu, Gang, Guo, Qing-Long, Yang, Jian, Wang, Hao
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01.05.2016; Wiley Subscription Services, Inc
• Subjects: Acetylcysteine; Animal models; Animals; Antineoplastic Agents, Phytogenic - administration & dosage; Antineoplastic Agents, Phytogenic - pharmacology; Antitumor activity; Apoptosis; aspafilioside B; Asparagus; Carcinoma, Hepatocellular - drug therapy; Carcinoma, Hepatocellular - genetics; Cell cycle; Cell Line, Tumor; Cell lines; Cell Proliferation - drug effects; Cell Survival - drug effects; Chemotherapy; Cysteine; Cytotoxicity; Enzyme inhibitors; Extracellular signal-regulated kinase; Female; G2 arrest; G2 phase; G2 Phase Cell Cycle Checkpoints - drug effects; Gene Expression Regulation, Neoplastic - drug effects; Genes, ras - drug effects; H-Ras; H-Ras protein; Hep G2 Cells; Hepatoma; Humans; Kinases; Liver cancer; Liver Neoplasms - drug therapy; Liver Neoplasms - genetics; Lymphocytes B; MAP kinase; MAP Kinase Signaling System - drug effects; Mice; N-Ras; Phosphorylation; Raf protein; Ras protein; Reactive oxygen species; Saponins - administration & dosage; Saponins - pharmacology; Spirostans - administration & dosage; Spirostans - pharmacology; Transfection; Xenograft Model Antitumor Assays; Xenografts; apoptosis; aspafilioside B; H-Ras; G2 arrest; N-Ras
• ISSN: 0899-1987; 1098-2744; 1098-2744
• DOI: 10.1002/mc.22293

We recently establish that aspafilioside B, a steroidal saponin extracted from Asparagus filicinus, is an active cytotoxic component. However, its antitumor activity is till unknown. In this study, the anticancer effect of aspafilioside B against HCC cells and the underlying mechanisms were investigated. Our results showed that aspafilioside B inhibited the growth and proliferation of HCC cell lines. Further study revealed that aspafilioside B could significantly induce G2 phase cell cycle arrest and apoptosis, accompanying the accumulation of reactive oxygen species (ROS), but blocking ROS generation with N‐acetyl‐l‐cysteine (NAC) could not prevent G2/M arrest and apoptosis. Additionally, treatment with aspafilioside B induced phosphorylation of extracellular signal‐regulated kinase (ERK) and p38 MAP kinase. Moreover, both ERK inhibitor PD98059 and p38 inhibitor SB203580 almost abolished the G2/M phase arrest and apoptosis induced by aspafilioside B, and reversed the expression of cell cycle‐ and apoptosis‐related proteins. We also found that aspafilioside B treatment increased both Ras and Raf activation, and transfection of cells with H‐Ras and N‐Ras shRNA almost attenuated aspafilioside B‐induced G2 phase arrest and apoptosis as well as the ERK and p38 activation. Finally, in vivo, aspafilioside B suppressed tumor growth in mouse xenograft models, and the mechanism was the same as in vitro study. Collectively, these findings indicated that aspafilioside B may up‐regulate H‐Ras and N‐Ras, causing c‐Raf phosphorylation, and lead to ERK and p38 activation, which consequently induced the G2 phase arrest and apoptosis. This study provides the evidence that aspafilioside B is a promising therapeutic agent against HCC. © 2015 Wiley Periodicals, Inc.