title: Cytotoxicity of the matrix metalloproteinase-activated anthrax lethal toxin is dependent on gelatinase expression and B-RAF status in human melanoma cells.
abstract: Anthrax lethal toxin (LeTx) shows potent mitogen-activated protein kinase pathway inhibition and apoptosis in melanoma cells that harbor the activating V600E B-RAF mutation. LeTx is composed of two proteins, protective antigen and lethal factor. Uptake of the toxin into cells is dependent on proteolytic activation of protective antigen by the ubiquitously expressed furin or furin-like proteases. To circumvent nonspecific LeTx activation, a substrate preferably cleaved by gelatinases was substituted for the furin LeTx activation site. Here, we have shown that the toxicity of this matrix metalloproteinase (MMP)-activated LeTx is dependent on host cell surface MMP-2 and MMP-9 activity as well as the presence of the activating V600E B-RAF mutation, making this toxin dual specific. This additional layer of tumor cell specificity would potentially decrease systemic toxicity from the reduction of nonspecific toxin activation while retaining antitumor efficacy in patients with V600E B-RAF melanomas. Moreover, our results indicate that cell surface-associated gelatinase expression can be used to predict sensitivity among V600E B-RAF melanomas. This finding will aid in the better selection of patients that will potentially respond to MMP-activated LeTx therapy.
authors.affiliation: Scott & White Cancer Research Institute Memorial Hospital, 5701 South Airport Road, Temple, TX 76502, USA.
authors.forename: Randall W
authors.initials: RW
authors.lastname: Alfano
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Leppla
authors.forename: Shihui
authors.initials: S
authors.lastname: Liu
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Bugge
authors.forename: Meenhard
authors.initials: M
authors.lastname: Herlyn
authors.forename: Keiran S
authors.initials: KS
authors.lastname: Smalley
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Bromberg-White
authors.forename: Nicholas S
authors.initials: NS
authors.lastname: Duesbery
authors.forename: Arthur E
authors.initials: AE
authors.lastname: Frankel
mesh_terms: D000942:Antigens, Bacterial / Q000633:toxicity*; D000970:Antineoplastic Agents / Q000633:toxicity*; D001427:Bacterial Toxins / Q000633:toxicity*; D045744:Cell Line, Tumor; D018093:Gelatinases / Q000378:metabolism*; D006801:Humans; D020782:Matrix Metalloproteinases / Q000378:metabolism*; D008545:Melanoma / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics* / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D000942:Antigens, Bacterial; D000970:Antineoplastic Agents; D001427:Bacterial Toxins; C030325:anthrax toxin; D048493:Proto-Oncogene Proteins B-raf; D018093:Gelatinases; D020782:Matrix Metalloproteinases