PMID:19472336

Citation	Bergelt, S, Frost, S and Lilie, H (2009) Listeriolysin O as cytotoxic component of an immunotoxin. Protein Sci. 18:1210-20
Abstract	Monoclonal antibodies (mAbs) have been developed over the past years as promising anticancer therapeutics. The conjugation of tumor specific mAbs with cytotoxic molecules has been shown to improve their efficacy dramatically. These bifunctional immunotoxins, consisting of covalently linked antibodies and protein toxins, possess considerable potential in cancer therapy. Many of them are under investigation in clinical trials. As a result of general interest in new toxic components, we describe here the suitability of the bacterial protein Listeriolysin O (LLO) as cytotoxic component of an immunotoxin. Unique characteristics of LLO, such as its acidic pH optimum and the possibility to regulate the cytolytic activity by cysteine-oxidation, make LLO an interesting toxophore. Oxidized LLO shows a substantially decreased cytolytic activity when compared with the reduced protein as analyzed by hemolysis. Both oxidized and reduced LLO exhibit a cell-type-unspecific toxicity in cell culture with a significantly higher toxicity of reduced LLO. For cell-type-specific targeting of LLO to tumor cells, LLO was coupled to the dsFv fragment of the monoclonal antibody B3, which recognizes the tumor-antigen Lewis Y. The coupling of LLO to dsFv-B3 was performed via cysteine-containing polyionic fusion peptides that act as a specific heterodimerization motif. The novel immunotoxin B3-LLO could be shown to specifically eliminate antigen positive MCF7 cells with an EC(50) value of 2.3 nM, whereas antigen negative cell lines were 80- to 250-fold less sensitive towards B3-LLO.
Links	PubMed PMC2774431 Online version:10.1002/pro.130
Keywords	Antibodies, Monoclonal/chemistry; Antibodies, Monoclonal/immunology; Antibodies, Monoclonal/therapeutic use; Bacterial Toxins/chemistry; Bacterial Toxins/immunology; Bacterial Toxins/therapeutic use; Cell Line, Tumor; Cloning, Molecular; Cytotoxicity, Immunologic; Heat-Shock Proteins/chemistry; Heat-Shock Proteins/immunology; Heat-Shock Proteins/therapeutic use; Hemolysin Proteins/chemistry; Hemolysin Proteins/immunology; Hemolysin Proteins/therapeutic use; Hemolysis/drug effects; Hemolysis/immunology; Humans; Immunotoxins/chemistry; Immunotoxins/immunology; Immunotoxins/therapeutic use; Lewis Blood-Group System/immunology; Lewis Blood-Group System/metabolism; Protein Conformation; Recombinant Proteins/chemistry; Recombinant Proteins/immunology; Recombinant Proteins/therapeutic use
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
LISMN:Q6E8U6		GO:0009405: pathogenesis	ECO:0000314:		P		Figure 4. Sheep erythrocytes treated with both known immunotoxin and suspected cytotoxic LLC to compare effects on cell death	complete CACAO 9121

References

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