Bcl-2 protects against beta-lapachone-mediated caspase 3 activation and apoptosis in human myeloid leukemia (HL-60) cells.
We previously demonstrated that beta-lapachone (beta-lap) killed cancer cells solely by apoptosis. Beta-Lap induced apoptosis in HL-60 cells in a dose-dependent manner as measured by flow cytometry and DNA ladder formation. Cell cycle changes, such as accumulations in S and G2-phases, were not observed. Apoptosis was accompanied by activation of caspase 3 and concomitant cleavage of poly(ADP-ribose) polymerase (PARP) to an 89 kDa polypeptide. PARP cleavage was blocked by zDEVD-fmk or zVAD-fmk, caspase-specific cleavage site inhibitors. Retrovirally introduced bcl-2 prevented beta-lap-mediated caspase 3 activation and PARP cleavage and increased the viability of Bcl-2-expressing HL-60 cells compared to cells with vector alone. Various beta-lap-related analogs (e.g., dunnione and naphthoquinone derivatives) induced equivalent apoptosis in HL-60 cells, but no compound was more effective than beta-lap. These data provide further evidence that the primary mode of cell killing by beta-lap is by the initiation and execution of apoptosis in human cancer cells.
Planchon
S M
SM
Department of Radiation Oncology, Laboratory of Molecular Stress Responses, Case Western Reserve University, Cleveland, OH 44106, USA.
Wuerzberger-Davis
S M
SM
Pink
J J
JJ
Robertson
K A
KA
Bornmann
W G
WG
Boothman
D A
DA
D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D005822:Genetic Vectors; D018922:HL-60 Cells / Q000166:cytology / Q000201:enzymology; D006801:Humans; D009285:Naphthoquinones / Q000493:pharmacokinetics / Q000633:toxicity*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*
D009285:Naphthoquinones; D011480:Protease Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; C014638:beta-lapachone; D011065:Poly(ADP-ribose) Polymerases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases