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

Abstract

Caspase-3 deficiency can limit the efficiency of pro-apoptotic anticancer treatments. Irofulven (hydroxymethylacyl-fulvene, 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 microM irofulven (approximately 3 x 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 microM drug with only approximately 3-9% fragmented DNA after 12-48 h, although apoptosis was observed at drug levels >3 microM. The broad-spectrum caspase inhibitor Z-VAD-fmk inhibited irofulven-induced apoptosis of all cell lines at 20 microM with nearly complete abrogation of apoptosis at 100 microM. 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).

• Authors: Maryanne C S Herzig, Huiyun Liang, Anne E Johnson, Barbara Woynarowska, Jan M Woynarowski
• Journal: Breast cancer research and treatment (Breast Cancer Res Treat) Vol. 71 Issue 2 Pg. 133-43 (Jan 2002) ISSN: 0167-6806 [Print] Netherlands
• PMID: 11883439 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Antineoplastic Agents, Alkylating
• Sesquiterpenes
• irofulven
• CASP3 protein, human
• Caspase 3
• Caspases

Topics

• Antineoplastic Agents, Alkylating (toxicity)
• Apoptosis (drug effects)
• Breast Neoplasms (pathology)
• Caspase 3
• Caspases (metabolism)
• Cell Survival (drug effects)
• DNA Fragmentation (drug effects)
• Enzyme Activation
• Female
• Humans
• Kinetics
• Sesquiterpenes (toxicity)
• Tumor Cells, Cultured