Irofulven induces apoptosis in breast cancer cells regardless of caspase-3 status

Maryanne C.S. Herzig, Huiyun Liang, Anne E. Johnson, Barbara Woynarowska, Jan M. Woynarowski

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Caspase-3 deficiency can limit the efficiency of pro-apoptotic anticancer treatments. Irofulven (hydroxymethylacylfulvene, HMAF, MGI 114, NSC 683863) is an antitumor drug, currently in a Phase III and multiple Phase II trials, which can differentiate between tumor and normal cells in apoptosis induction. This study investigated whether apoptosis induced by irofulven requires caspase-3. Irofulven action was compared in breast cancer cells differing in caspase-3 status: deficient MCF-7 cells and proficient MDA-MB-231 cells and in normal human mammary epithelial cells, HMEC. Irofulven induces significant, concentration and time-dependent apoptotic DNA fragmentation in breast cancer cell lines, regardless of caspase-3 status. After 12, 24 and 48 h incubation at 1 μM irofulven (∼3 × GI50), fragmented DNA comprised 3.7, 14.1 and 34.6% and 8.4, 12.6 and 20.3% of total DNA in MCF-7 and MDA-MB-231 cells, respectively. Cell viability (trypan blue exclusion) remained largely unaffected during the first 24 h but decreased markedly after 48 h, indicating secondary necrosis. Net losses in cell numbers were apparent at 48 h. Normal HMEC cells were refractory to 1 μM drug with only ∼3-9% fragmented DNA after 12-48 h, although apoptosis was observed at drug levels >3 μM. The broad-spectrum caspase inhibitor Z-VAD-fmk inhibited irofulven-induced apoptosis of all cell lines at 20 μM with nearly complete abrogation of apoptosis at 100 μM. Irofulven treatment resulted in marginal caspase-3 processing in MDA-MB-231 and HMEC cells. These results indicate that whereas the caspase cascade mediates irofulven- induced apoptosis, caspase-3 is dispensable (supported by NIH CA70091 and CA78706).

Original languageEnglish (US)
Pages (from-to)133-143
Number of pages11
JournalBreast Cancer Research and Treatment
Volume71
Issue number2
DOIs
StatePublished - Feb 26 2002

Keywords

  • Apoptosis
  • Apoptosis resistance
  • Caspase-3
  • Irofulven
  • MCF-7 cells

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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