Baculovirus p35 and Z-VAD-fmk inhibit thapsigargin-induced apoptosis of breast cancer cells

Oncogene. 1997 Sep 4;15(10):1207-12. doi: 10.1038/sj.onc.1201290.


Programmed cell death, or apoptosis, is inhibited by the antiapoptotic oncogene, Bcl-2, and is mediated by a cascade of aspartate-specific cysteine proteases, or caspases, related to interleukin 1-beta converting enzyme. Depending on cell type, apoptosis can be induced by treatment with thapsigargin (TG); a selective inhibitor of the endoplasmic reticulum-associated calcium-ATPase. The role of caspases in mediating TG-induced apoptosis was investigated in the Bcl-2-negative human breast cancer cell line, MDA-MB-468. Apoptosis developed in MDA-MB-468 cells over a period of 24-72 h following treatment with 100 nM TG, and was prevented by Bcl-2 overexpression. TG-induced apoptosis was associated with activation of caspase-3 and was inhibited by stable expression of the baculovirus p35 protein, an inhibitor of caspase activity. Also, TG-induced apoptosis was inhibited by treating cells with Z-VAD-fmk, a cell-permeable fluoromethylketone inhibitor of caspases. These findings indicate that TG-induced apoptosis of MDA-MB-468 breast cancer cells is subject to inhibition by Bcl-2 and is mediated by caspase activity. This model system should be useful for further investigation directed toward understanding the role of calcium in signaling apoptosis, and its relationship to Bcl-2 and the caspase proteolytic cascade.

Publication types

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

MeSH terms

  • Amino Acid Chloromethyl Ketones / pharmacology*
  • Apoptosis / drug effects*
  • Breast Neoplasms / pathology*
  • Caspase 3
  • Caspases*
  • Cysteine Endopeptidases / metabolism
  • Cysteine Endopeptidases / physiology*
  • Cysteine Proteinase Inhibitors / pharmacology*
  • Enzyme Activation
  • Humans
  • Inhibitor of Apoptosis Proteins
  • Proto-Oncogene Proteins c-bcl-2 / physiology*
  • Signal Transduction
  • Thapsigargin / pharmacology*
  • Tumor Cells, Cultured
  • Viral Proteins / pharmacology*


  • Amino Acid Chloromethyl Ketones
  • Cysteine Proteinase Inhibitors
  • Inhibitor of Apoptosis Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • Viral Proteins
  • benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone
  • inhibitor of apoptosis, Nucleopolyhedrovirus
  • Thapsigargin
  • CASP3 protein, human
  • Caspase 3
  • Caspases
  • Cysteine Endopeptidases