Irofulven (6-hydroxymethylacylfulvene, MGI 114) induces caspase 8 and 9-mediated apoptosis in human pancreatic adenocarcinoma cells.

BACKGROUND: Irofulven (MGI 114) is a novel, clinically active sesquiterpene whose mechanism of action is not fully understood. We sought to identify apoptotic effectors induced by this agent in human pancreatic cancer cells.
MATERIALS AND METHODS: MTT assay was used to assess IC50-Apoptosis was quantitated by flow cytometry and DAPI staining. Caspase activation was identified by western blot analysis.
RESULTS: Irofulven was cytotoxic against all pancreatic cancer cell lines tested (IC50 1-18 microM), and induced 10-fold (4%+/- 2, vs. 41% +/- 5) induction of apoptosis. Irofulven-treated cells also demonstrated PARP3 cleavage and DAPI staining. Apoptosis was reduced to baseline levels by Z-VAD-FMK, a broad-spectrum caspase inhibitor. Western blot analysis revealed that caspases-3, -7, -8, and -9 were activated by irofulven. Time course evaluation demonstrated that caspases-8 and -9 were the initial species activated.
CONCLUSION: Our data demonstrate that the cytotoxicity of irofulven in human pancreatic carcinoma cell lines is mediated by caspase-induced apoptosis.