Necrotic, rather than apoptotic, cell death caused by cytochrome P450–activated ifosfamide

Abstract

Feline kidney cells were transfected with a vector overexpressing cytochrome P450 2B1 ( CYP2B1 ) . Transfected cells acquired a new specific biochemical activity, which could be demonstrated by a rapid CYP2B1 detection assay and showed selective sensitivity to the antitumorigenic prodrug ifosfamide ( IFO ) . Further, the cell -killing effect was also mediated on nonmodified cells like feline kidney cells, mouse lymphoma, and human pancreatic cells in the vicinity of the CYP2B1 -expressing cells due to the diffusible nature of the activated IFO metabolites. One of these, phosphoramide mustard, causes interstrand DNA cross -linking and it has been thought that the inability to repair this damage results in apoptosis. Surprisingly, our results clearly demonstrate a necrotic mechanism of IFO -induced cell death. This may have important implications for the activation of the immune system during CYP2B1 / IFO suicide gene therapy of cancer. Cancer Gene Therapy ( 2001 ) 8, 220 ± 230

Heat- and 4-hydroperoxy-ifosfamide-induced apoptosis in B cell precursor leukaemias

“…Caspase-3,-8 and -9 activation was also observed in Chinese hamster cells, which were hypersensitive to the cytostatic drug -d-glucose-ifosfamide mustard 37 . In contrast to these reports, Karle et al 38 demonstrated a necrotic rather than an apoptotic mechanism of an activated ifosfamide metabolite, phosphoramide mustard, on various tumour cells. However, the results regarding either the z-VAD-fmk experiments or else the caspase-3, -8 and -9 activities clearly demonstrate caspase-dependent apoptosis induced by 4OOH-IFA in human leukaemia cells.…”

Use of Replication-Conditional Adenovirus as a Helper System to Enhance Delivery of P450 Prodrug-Activation Genes for Cancer Therapy

“…6, 7). CPA and IFA are alkylating agent prodrugs that induce DNA cross-linking in a cell cycle-independent manner, and ultimately trigger a mitochondrial pathway apoptotic cell death in the case of CPA (8) and either apoptosis or necrosis in the case of IFA (8,9). CPA and IFA are activated by a subset of liver-expressed P450 enzymes (10,11), which catalyze a 4-hydroxylation reaction that yields cell membrane-permeable, cytotoxic metabolites.…”

Results of a phase II clinical trial on the use of ifosfamide for treatment of cats with vaccine-associated sarcomas

“…Feline kidney cells have been transfected with a vector that overexpresses cytochrome P450-2B1. 36 Transfected cells acquire biochemical activity and are able to activate prodrug ifosfamide, but the potential deleterious effects of inactive metabolites have not been examined. Mesna (sodium 2-mercaptoethanesulfonate) combines with acrolein in the urinary bladder and is effective in preventing urothelial toxicosis in humans treated with ifosfamide; however, it does not protect against ifosfamideinduced nephrotoxicosis.…”