Ca2+/Mg2+-dependent endonuclease activation is an early event in VP-16-induced apoptosis of human breast cancer MCF7 cells in vitro

Irina A. Sokolova, Kenneth H. Cowan, Erasmus Schneider

Research output: Contribution to journalArticle

37 Scopus citations


Apoptosis is now recognized as one of the major processes regulating the size of cell populations. However, despite intensive investigations the biochemical and enzymological mechanisms involved in apoptosis remain unclear. In the present study we demonstrate activation of a Ca2+/Mg2+-dependent endonuclease during VP-16-induced apoptosis in MCF7 cells. Nuclease activation occurred prior to the appearance of internucleosomal DNA fragmentation, suggesting that this activation may be an early and possibly critical step in drug-induced apoptosis. Analysis of the internucleosomal DNA fragments showed that they contained phosphorylated 5′-ends indicating that they were produced by a Ca2+/Mg2+-dependent endonuclease.

Original languageEnglish (US)
Pages (from-to)135-142
Number of pages8
JournalBiochimica et Biophysica Acta - Molecular Cell Research
Issue number2
StatePublished - Jan 1 1995



  • 10 mM Tris-HCl/1 m1vl EDTA (pH 8.0)
  • 40 mM Tris-acetate/2 mM EDTA (pH 7.8)
  • 4′,6-diamino-2-phenylindole
  • 5-FdUrd
  • 5-fluoro-2′-deoxyuridine
  • Apoptosis
  • CIAP
  • DAPI
  • DNA fragmentation
  • Endonuclease
  • PBS
  • SDS
  • TAE buffer
  • TE buffer
  • VP-16
  • calf intestinal alkaline phosphatase
  • etoposide
  • phosphate buffer solution
  • sodium dodecyl sulfate

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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