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.
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.
Reiners
John J
JJ
Institute of Environmental Health Sciences, Wayne State University, 2727 Second Avenue, Room 4000, Detroit, MI 48201, USA. john.reiners.jr@wayne.edu
Kessel
David
D
D017209:Apoptosis / Q000187:drug effects*; D001578:Benzopyrans / Q000494:pharmacology*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects*; D004171:Diploidy; D004791:Enzyme Inhibitors / Q000378:metabolism*; D006801:Humans; D008024:Ligands; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D009570:Nitriles / Q000494:pharmacology*; D010446:Peptide Fragments / Q000737:chemistry*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D014343:Trypan Blue; D020298:U937 Cells / Q000187:drug effects
D001578:Benzopyrans; D004791:Enzyme Inhibitors; D008024:Ligands; D009570:Nitriles; D010446:Peptide Fragments; D019253:Proto-Oncogene Proteins c-bcl-2; C456800:ethyl 2-amino-6-bromo-4-(1-cyano-2-ethoxy-2-oxoethyl)-4H-chromene-3-carboxylate; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D014343:Trypan Blue