Susceptibility of myelomonocytic leukemia U937 cells to the induction of apoptosis by the non-peptidic Bcl-2 ligand HA14-1 is cell cycle phase-dependent

Cancer Lett. 2005 Apr 28;221(2):153-63. doi: 10.1016/j.canlet.2004.09.012.


Pharmacological approaches employing agents that bind to the Bcl-2 surface pocket have been used successfully to neutralize the activities of anti-apoptotic Bcl-2 family members, and induce apoptosis. Several reports suggest that Bcl-2 expression/function is cell cycle-dependent. Hence, is killing by Bcl-2 surface pocket binding agents also cell cycle-dependent? In the current study, centrifugal elutriation was used to generate cell cycle phase-enriched preparations of the human myelomonocytic leukemia cell line U937. Elutriated fractions were treated with sub-optimal cytotoxic concentrations of the pro-apoptotic, non-peptidic Bcl-2 pocket-binding agent HA14-1. A concentration of HA14-1 sufficient to kill approximately 30-35% of asynchronous cultures minimally affected the progressions of elutriated post-checkpoint G1, S, G2/M phase cells, but completely suppressed the progression of pre-G1 checkpoint G1 cells. Analyses of trypan blue exclusion, morphology, nuclear condensation, mitochondrial membrane potential, sub-diploid DNA contents, and caspase-3 indicated preferential killing and induction of apoptosis in pre-G1 checkpoint G1 and G2/M phase cells.

Publication types

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

MeSH terms

  • Apoptosis / drug effects*
  • Benzopyrans / pharmacology*
  • Caspase 3
  • Caspases / metabolism
  • Cell Cycle / drug effects*
  • Diploidy
  • Enzyme Inhibitors / metabolism*
  • Humans
  • Ligands
  • Membrane Potentials / drug effects
  • Mitochondria / drug effects
  • Mitochondria / metabolism
  • Nitriles / pharmacology*
  • Peptide Fragments / chemistry*
  • Proto-Oncogene Proteins c-bcl-2 / metabolism*
  • Trypan Blue
  • U937 Cells / drug effects


  • Benzopyrans
  • Enzyme Inhibitors
  • Ligands
  • Nitriles
  • Peptide Fragments
  • Proto-Oncogene Proteins c-bcl-2
  • ethyl 2-amino-6-bromo-4-(1-cyano-2-ethoxy-2-oxoethyl)-4H-chromene-3-carboxylate
  • CASP3 protein, human
  • Caspase 3
  • Caspases
  • Trypan Blue