AT514, a cyclic depsipeptide from Serratia marcescens, induces apoptosis of B-chronic lymphocytic leukemia cells: interference with the Akt/NF-kappaB survival pathway

Leukemia. 2005 Apr;19(4):572-9. doi: 10.1038/sj.leu.2403679.

Abstract

Clinical treatment of B-cell chronic lymphocytic leukemia (B-CLL) is limited by the progressive drug resistance and nonselectivity of most drugs towards malignant cells. Depsipeptides are present in certain bacteria and display potent antitumor activity. We have studied the effect of the novel cyclodepsipeptide AT514 (serratamolide) from Serratia marcescens on B-CLL cell viability. AT514 induced apoptosis of B-CLL cells from the 21 patients studied, as confirmed by Annexin-V binding and nuclei condensation, with an average IC50 of 13 microM. AT514 was effective in those B-CLL cases resistant to fludarabine, but had no effect on normal PBL. AT514 preferentially activated the intrinsic apoptotic pathway, as evidenced by loss of mitochondrial membrane potential, release of cytochrome c and activation of caspase-9 and -3, but not of caspase-8. Importantly, AT514 interfered with phosphatidylinositol-3 kinase and protein kinase C survival signals since it increased the apoptotic effect of LY294002 and Bisl inhibitors, and induced Akt dephosphorylation at Ser 473. AT514 also decreased NF-kappaB activity by dramatically reducing the levels of p65 in B-CLL. This was confirmed on functional assays using NF-kappaB-luc-transfected Raji cells and transgenic mice. Our results establish that AT514 induces apoptosis of primary B-CLL cells and could be useful for clinical treatment of this malignancy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects*
  • Caspase 3
  • Caspase 9
  • Caspases / metabolism
  • Cell Survival / drug effects
  • Cytochromes c / metabolism
  • Depsipeptides / pharmacology
  • Humans
  • In Vitro Techniques
  • Leukemia, B-Cell / drug therapy
  • Leukemia, Lymphocytic, Chronic, B-Cell / drug therapy*
  • Luciferases / genetics
  • Membrane Potentials / drug effects
  • Mice
  • Mice, Transgenic
  • Mitochondria / physiology
  • NF-kappa B / genetics
  • NF-kappa B / metabolism*
  • Peptides, Cyclic / pharmacology*
  • Protein-Serine-Threonine Kinases / metabolism*
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-akt
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • Serratia marcescens / chemistry*
  • Transfection
  • bcl-2-Associated X Protein

Substances

  • Depsipeptides
  • NF-kappa B
  • Peptides, Cyclic
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • bcl-2-Associated X Protein
  • serratamolide
  • Cytochromes c
  • Luciferases
  • AKT1 protein, human
  • Protein-Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt
  • CASP3 protein, human
  • CASP9 protein, human
  • Casp3 protein, mouse
  • Casp9 protein, mouse
  • Caspase 3
  • Caspase 9
  • Caspases