The pivotal role of c-Jun NH2-terminal kinase-mediated Beclin 1 expression during anticancer agents-induced autophagy in cancer cells

Oncogene. 2009 Feb 12;28(6):886-98. doi: 10.1038/onc.2008.441. Epub 2008 Dec 8.

Abstract

The c-Jun NH2-terminal kinase (JNK) pathway represents one subgroup of MAP kinases that are activated primarily by cytokines and exposure to environmental stress. Autophagy is a protein-degradation system characterized by the formation of double-membrane vacuoles termed autophagosomes. Autophagy-related gene beclin 1 plays a key role in autophagosome formation. However, the relationships between activation of JNK pathway, autophagy induction and Beclin 1 expression remain elusive. In this study, we used human cancer cell lines CNE2 and Hep3B to investigate the role of JNK-mediated Beclin 1 expression in ceramide-induced autophagic cell death. Ceramide-treated cells exhibited the characteristics of autophagy (that is, acidic vesicular organelle formation and the LC3-II generation). JNK was activated in these two cell lines exposed to ceramide and the phosphorylation of c-Jun also increased. In the meantime, we found that ceramide upregulated Beclin 1 expression in cancer cells. The upregulation of Beclin 1 expression could be blocked by SP600125 (a specific inhibitor of JNK) or a small interfering RNA (siRNA) directed against JNK1/2 or c-Jun. Chromatin immunoprecipitation and luciferase reporter analysis revealed that c-Jun was involved in the regulation of beclin 1 transcription in response to ceramide treatment. In addition, inhibition of JNK activity by SP600125 could inhibit autophagy induction by ceramide. Furthermore, Beclin 1 knockdown by siRNA also inhibited ceramide-mediated autophagic cell death. JNK-mediated Beclin 1 expression was also observed in topotecan-induced autophagy. These data suggest that activation of JNK pathway can mediate Beclin 1 expression, which plays a key role in autophagic cell death in cancer cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anthracenes / pharmacology
  • Antineoplastic Agents / pharmacology*
  • Apoptosis Regulatory Proteins / metabolism*
  • Autophagy*
  • Beclin-1
  • Caspase 3 / metabolism
  • Cell Line, Tumor
  • Ceramides / metabolism
  • Enzyme Inhibitors / pharmacology
  • Gene Expression Regulation, Neoplastic*
  • Humans
  • JNK Mitogen-Activated Protein Kinases / metabolism*
  • MAP Kinase Kinase 4 / metabolism
  • Membrane Proteins / metabolism*
  • Phagosomes / metabolism
  • Phosphorylation
  • RNA, Small Interfering / metabolism

Substances

  • Anthracenes
  • Antineoplastic Agents
  • Apoptosis Regulatory Proteins
  • BECN1 protein, human
  • Beclin-1
  • Ceramides
  • Enzyme Inhibitors
  • Membrane Proteins
  • RNA, Small Interfering
  • pyrazolanthrone
  • JNK Mitogen-Activated Protein Kinases
  • MAP Kinase Kinase 4
  • Caspase 3