Translational regulation of x-linked inhibitor of apoptosis protein by interleukin-6: a novel mechanism of tumor cell survival

Cancer Res. 2004 Feb 15;64(4):1293-8. doi: 10.1158/0008-5472.can-03-2517.

Abstract

Interleukin-6 (IL-6) is a pleiotropic cytokine with diverse biological effects. IL-6 has been implicated in autocrine signaling pathways promoting tumor progression and chemoresistance in some human tumors. However, the mechanisms by which IL-6 modulates these responses are unknown. Aberrant apoptosis has been implicated as a fundamental mechanism of chemotherapeutic resistance. Thus, we investigated whether IL-6 alters the expression of apoptosis regulatory proteins as a mechanism of drug resistance. We provide evidence that IL-6 rapidly phosphorylates the translation initiation factor eukaryotic initiation factor-4E and triggers antiapoptotic responses in cholangiocarcinoma cells. Reduction of cellular eukaryotic initiation factor-4E by RNA interference decreases IL-6-induced effects on cytotoxic drug-induced caspase activation and apoptosis. Furthermore, IL-6 increases expression of the endogenous X-linked inhibitor of apoptosis protein expression by translation at an internal ribosome entry site. Our findings that IL-6 translationally regulates X-linked inhibitor of apoptosis protein expression reveal a novel mechanism by which IL-6 mediates tumor cell survival that may be targeted therapeutically to decrease tumor progression and chemoresistance.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Antineoplastic Agents / pharmacology
  • Apoptosis / drug effects
  • Camptothecin / pharmacology
  • Cell Survival / drug effects
  • Cells, Cultured
  • Cholangiocarcinoma / drug therapy
  • Eukaryotic Initiation Factor-4E / metabolism
  • Humans
  • Interleukin-6 / pharmacology*
  • Phosphorylation
  • Protein Biosynthesis / drug effects*
  • Proteins / genetics*
  • X-Linked Inhibitor of Apoptosis Protein

Substances

  • Antineoplastic Agents
  • Eukaryotic Initiation Factor-4E
  • Interleukin-6
  • Proteins
  • X-Linked Inhibitor of Apoptosis Protein
  • XIAP protein, human
  • Camptothecin