BAD induces apoptosis in cells over-expressing Bcl-2 or Bcl-xL without loss of mitochondrial membrane potential.
Inhibitors of Bcl-2 may be useful therapeutic agents for the treatment of a wide variety of malignancies including leukemia. A potential prototype of such a compound is the endogenous Bcl-2 and Bcl-xL binding protein BAD. Previous reports indicate that BAD can overcome the anti-apoptotic effect of Bcl-xL but not Bcl-2. If BAD cannot induce apoptosis in cells over-expressing Bcl-2, it would limit the application of molecules like BAD as novel anti-tumor agents. We report that transient transfection of BAD induced cell death in cells with and without over-expression of Bcl-2 or Bcl-xL. Forty-eight hours after transfection, BAD increased cell death in COS, COS Bcl-2, and COS Bcl-xL cells as demonstrated by decreased GFP expression, and an increase in the number of number of floating cells. In addition, BAD induced cell death in leukemic cell lines over-expressing Bcl-2 and Bcl-xL as determined by changes in luciferase activity. BAD-induced apoptosis was not accompanied by loss of mitochondrial membrane potential. Therefore, we conclude that transient transfection of BAD directly induces apoptosis in cells over-expressing Bcl-2 or Bcl-xL and validates the pursuit of molecules like BAD as novel therapeutic agents.
Schimmer
A D
AD
Princess Margaret Hospital, University Health Network, Toronto, ON, Canada.
Hedley
D W
DW
Pham
N A
NA
Chow
S
S
Minden
M D
MD
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D018414:CD8-Positive T-Lymphocytes / Q000502:physiology; D019556:COS Cells; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D016923:Cell Death; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D003574:Cytochrome c Group / Q000235:genetics; D018076:DNA, Complementary; D017930:Genes, Reporter; D019254:Genes, bcl-2 / Q000235:genetics*; D049452:Green Fluorescent Proteins; D006801:Humans; D007425:Intracellular Membranes / Q000502:physiology; D020014:K562 Cells; D007700:Kinetics; D008164:Luminescent Proteins / Q000235:genetics; D008564:Membrane Potentials / Q000502:physiology*; D008928:Mitochondria / Q000502:physiology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics*; D014162:Transfection; D051025:bcl-Associated Death Protein; D051020:bcl-X Protein
C494819:BAD protein, human; C494811:BCL2L1 protein, human; D002352:Carrier Proteins; D003574:Cytochrome c Group; D018076:DNA, Complementary; D008164:Luminescent Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051025:bcl-Associated Death Protein; D051020:bcl-X Protein; D049452:Green Fluorescent Proteins