Triptolide induces growth inhibition and apoptosis of human laryngocarcinoma cells by enhancing p53 activities and suppressing E6-mediated p53 degradation

PLoS One. 2013 Nov 14;8(11):e80784. doi: 10.1371/journal.pone.0080784. eCollection 2013.

Abstract

Triptolide, an active compound extracted from Chinese herb Leigongteng (Tripterygium wilfordii Hook F.), shows a broad-spectrum of anticancer activity through its cytotoxicity. However, the efficacy of triptolide on laryngocarcinoma rarely been evaluated, and the mechanism by which triptolide-induced cellular apoptosis is still not well understood. In this study, we found that triptolide significantly inhibited the laryngocarcinoma HEp-2 cells proliferation, migration and survivability. Triptolide induces HEp-2 cell cycle arrest at the G1 phase and apoptosis through intrinsic and extrinsic pathways since both caspase-8 and -9 are activated. Moreover, triptolide enhances p53 expression by increasing its stability via down-regulation of E6 and E6AP. Increased p53 transactivates down-stream target genes to initiate apoptosis. In addition, we found that short time treatment with triptolide induced DNA damage, which was consistent with the increase in p53. Furthermore, the cytotoxicity of triptolide is decreased by p53 knockdown or use of caspases inhibitor. In conclusion, our results demonstrated that triptolide inhibits cell proliferation and induces apoptosis in laryngocarcinoma cells by enhancing p53 expression and activating p53 functions through induction of DNA damage and suppression of E6 mediated p53 degradation. These studies indicate that triptolide is a potential anti-laryngocarcinoma drug.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / pharmacology
  • Apoptosis / drug effects*
  • Cell Line, Tumor
  • Diterpenes / pharmacology*
  • Epoxy Compounds / pharmacology
  • Humans
  • Laryngeal Neoplasms / metabolism*
  • Oncogene Proteins, Viral / metabolism*
  • Phenanthrenes / pharmacology*
  • Tumor Suppressor Protein p53 / metabolism*

Substances

  • Antineoplastic Agents
  • Diterpenes
  • Epoxy Compounds
  • Oncogene Proteins, Viral
  • Phenanthrenes
  • Tumor Suppressor Protein p53
  • triptolide

Grants and funding

This work was supported by National Natural Science Foundation of China (61178084) and National Forestry Public Welfare Industry Research Project (201204603) to Ming lei; the Scientific Research Fund of the Second Hospital Xi 'an JiaoTong University (YJ(ZD)201207) and Science and Technology Research and Development Project in Shaanxi province (2011K3-03-09) to Xiaoyong Ren; the Starting Resaerch Fund from Northwest A&F University (Z111021306) to Weiwei Huang. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.