Targeting elongation factor-2 kinase (eEF-2K) induces apoptosis in human pancreatic cancer cells

Apoptosis. 2014 Jan;19(1):241-58. doi: 10.1007/s10495-013-0927-2.

Abstract

Pancreatic cancer (PaCa) is one of the most aggressive, apoptosis-resistant and currently incurable cancers with a poor survival rate. Eukaryotic elongation factor-2 kinase (eEF-2K) is an atypical kinase, whose role in PaCa survival is not yet known. Here, we show that eEF-2K is overexpressed in PaCa cells and its down-regulation induces apoptotic cell death. Rottlerin (ROT), a polyphenolic compound initially identified as a PKC-δ inhibitor, induces apoptosis and autophagy in a variety of cancer cells including PaCa cells. We demonstrated that ROT induces intrinsic apoptosis, with dissipation of mitochondrial membrane potential (ΔΨm), and stimulates extrinsic apoptosis with concomitant induction of TNF-related apoptosis inducing ligand (TRAIL) receptors, DR4 and DR5, with caspase-8 activation, in PANC-1 and MIAPaCa-2 cells. Notably, while none of these effects were dependent on PKC-δ inhibition, ROT down-regulates eEF-2K at mRNA level, and induce eEF-2K protein degradation through ubiquitin-proteasome pathway. Down-regulation of eEF-2K recapitulates the events observed after ROT treatment, while its over-expression suppressed the ROT-induced apoptosis. Furthermore, eEF-2K regulates the expression of tissue transglutaminase (TG2), an enzyme previously implicated in proliferation, drug resistance and survival of cancer cells. Inhibition of eEF-2K/TG2 axis leads to caspase-independent apoptosis which is associated with induction of apoptosis-inducing factor (AIF). Collectively, these results indicate, for the first time, that the down-regulation of eEF-2K leads to induction of intrinsic, extrinsic as well as AIF-dependent apoptosis in PaCa cells, suggesting that eEF-2K may represent an attractive therapeutic target for the future anticancer agents in PaCa.

MeSH terms

  • Acetophenones / pharmacology
  • Antineoplastic Agents / pharmacology
  • Apoptosis Inducing Factor / genetics
  • Apoptosis Inducing Factor / metabolism
  • Apoptosis* / drug effects
  • Benzopyrans / pharmacology
  • Cell Line, Tumor
  • Elongation Factor 2 Kinase / antagonists & inhibitors
  • Elongation Factor 2 Kinase / genetics
  • Elongation Factor 2 Kinase / metabolism*
  • Humans
  • Pancreatic Neoplasms / drug therapy
  • Pancreatic Neoplasms / enzymology*
  • Pancreatic Neoplasms / genetics
  • Pancreatic Neoplasms / physiopathology
  • Signal Transduction / drug effects

Substances

  • Acetophenones
  • Antineoplastic Agents
  • Apoptosis Inducing Factor
  • Benzopyrans
  • rottlerin
  • Elongation Factor 2 Kinase