51
|
Álvarez C, Mancheño JM, Martínez D, Tejuca M, Pazos F, Lanio ME. Sticholysins, two pore-forming toxins produced by the Caribbean Sea anemone Stichodactyla helianthus: Their interaction with membranes. Toxicon 2009; 54:1135-47. [DOI: 10.1016/j.toxicon.2009.02.022] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
52
|
Bromberg-White JL, Boguslawski E, Duesbery NS. Perturbation of mouse retinal vascular morphogenesis by anthrax lethal toxin. PLoS One 2009; 4:e6956. [PMID: 19750016 PMCID: PMC2737623 DOI: 10.1371/journal.pone.0006956] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2009] [Accepted: 07/29/2009] [Indexed: 12/21/2022] Open
Abstract
Lethal factor, the enzymatic moiety of anthrax lethal toxin (LeTx) is a protease that inactivates mitogen activated protein kinase kinases (MEK or MKK). In vitro and in vivo studies demonstrate LeTx targets endothelial cells. However, the effects of LeTx on endothelial cells are incompletely characterized. To gain insight into this process we used a developmental model of vascularization in the murine retina. We hypothesized that application of LeTx would disrupt normal retinal vascularization, specifically during the angiogenic phase of vascular development. By immunoblotting and immunofluorescence microscopy we observed that MAPK activation occurs in a spatially and temporally regulated manner during retinal vascular development. Intravitreal administration of LeTx caused an early delay (4 d post injection) in retinal vascular development that was marked by reduced penetration of vessels into distal regions of the retina as well as failure of sprouting vessels to form the deep and intermediate plexuses within the inner retina. In contrast, later stages (8 d post injection) were characterized by the formation of abnormal vascular tufts that co-stained with phosphorylated MAPK in the outer retinal region. We also observed a significant increase in the levels of secreted VEGF in the vitreous 4 d and 8 d after LeTx injection. In contrast, the levels of over 50 cytokines other cytokines, including bFGF, EGF, MCP-1, and MMP-9, remained unchanged. Finally, co-injection of VEGF-neutralizing antibodies significantly decreased LeTx-induced neovascular growth. Our studies not only reveal that MAPK signaling plays a key role in retinal angiogenesis but also that perturbation of MAPK signaling by LeTx can profoundly alter vascular morphogenesis.
Collapse
Affiliation(s)
- Jennifer L. Bromberg-White
- Laboratory of Cancer and Developmental Cell Biology, Van Andel Research Institute, Grand Rapids, Michigan, United States of America
| | - Elissa Boguslawski
- Laboratory of Cancer and Developmental Cell Biology, Van Andel Research Institute, Grand Rapids, Michigan, United States of America
| | - Nicholas S. Duesbery
- Laboratory of Cancer and Developmental Cell Biology, Van Andel Research Institute, Grand Rapids, Michigan, United States of America
- * E-mail:
| |
Collapse
|
53
|
Cullen M, Seaman S, Chaudhary A, Yang MY, Hilton MB, Logsdon D, Haines DC, Tessarollo L, St. Croix B. Host-derived tumor endothelial marker 8 promotes the growth of melanoma. Cancer Res 2009; 69:6021-6. [PMID: 19622764 PMCID: PMC2721800 DOI: 10.1158/0008-5472.can-09-1086] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Tumor endothelial marker 8 (TEM8) was initially identified as a gene overexpressed in the vasculature of human tumors and was subsequently identified as an anthrax toxin receptor. To assess the functional role of TEM8, we disrupted the TEM8 gene in mice by targeted homologous recombination. TEM8(-/-) mice were viable and reached adulthood without defects in physiologic angiogenesis. However, histopathologic analysis revealed an excess of extracellular matrix in several tissues, including the ovaries, uterus, skin, and periodontal ligament of the incisors, the latter resulting in dental dysplasia. When challenged with B16 melanoma, tumor growth was delayed in TEM8(-/-) mice, whereas the growth of other tumors, such as Lewis lung carcinoma, was unaltered. These studies show that host-derived TEM8 promotes the growth of certain tumors and suggest that TEM8 antagonists may have utility in the development of new anticancer therapies.
Collapse
MESH Headings
- Animals
- Biomarkers, Tumor
- Carcinoma, Lewis Lung/blood supply
- Carcinoma, Lewis Lung/metabolism
- Carcinoma, Lewis Lung/pathology
- Female
- Male
- Melanoma, Experimental/blood supply
- Melanoma, Experimental/metabolism
- Melanoma, Experimental/pathology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Microfilament Proteins
- Neovascularization, Pathologic/pathology
- Receptors, Cell Surface
- Receptors, Peptide/biosynthesis
- Receptors, Peptide/deficiency
- Receptors, Peptide/genetics
- Receptors, Peptide/physiology
Collapse
Affiliation(s)
- Mike Cullen
- Tumor Angiogenesis Section, Mouse Cancer Genetics Program (MCGP), NCI-Frederick, Frederick, MD 21702, USA
| | - Steven Seaman
- Tumor Angiogenesis Section, Mouse Cancer Genetics Program (MCGP), NCI-Frederick, Frederick, MD 21702, USA
| | - Amit Chaudhary
- Tumor Angiogenesis Section, Mouse Cancer Genetics Program (MCGP), NCI-Frederick, Frederick, MD 21702, USA
| | - Mi Young Yang
- Tumor Angiogenesis Section, Mouse Cancer Genetics Program (MCGP), NCI-Frederick, Frederick, MD 21702, USA
| | - Mary Beth Hilton
- Tumor Angiogenesis Section, Mouse Cancer Genetics Program (MCGP), NCI-Frederick, Frederick, MD 21702, USA
- Basic Research Program, SAIC, NCI-Frederick, Frederick, MD 21702, USA
| | - Daniel Logsdon
- Basic Research Program, SAIC, NCI-Frederick, Frederick, MD 21702, USA
| | - Diana C. Haines
- Pathology/Histotechnology Laboratory, SAIC, NCI-Frederick, Frederick, MD 21702, USA
| | | | - Brad St. Croix
- Tumor Angiogenesis Section, Mouse Cancer Genetics Program (MCGP), NCI-Frederick, Frederick, MD 21702, USA
| |
Collapse
|
54
|
Moayeri M, Leppla SH. Cellular and systemic effects of anthrax lethal toxin and edema toxin. Mol Aspects Med 2009; 30:439-55. [PMID: 19638283 DOI: 10.1016/j.mam.2009.07.003] [Citation(s) in RCA: 175] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2009] [Accepted: 07/21/2009] [Indexed: 12/21/2022]
Abstract
Anthrax lethal toxin (LT) and edema toxin (ET) are the major virulence factors of anthrax and can replicate the lethality and symptoms associated with the disease. This review provides an overview of our current understanding of anthrax toxin effects in animal models and the cytotoxicity (necrosis and apoptosis) induced by LT in different cells. A brief reexamination of early historic findings on toxin in vivo effects in the context of our current knowledge is also presented.
Collapse
Affiliation(s)
- Mahtab Moayeri
- Bacterial Toxins and Therapeutics Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Building 33, Room 1W20B, Bethesda, MD 20892, USA.
| | | |
Collapse
|
55
|
Smith MJ, Culhane AC, Donovan M, Coffey JC, Barry BD, Kelly MA, Higgins DG, Wang JH, Kirwan WO, Cotter TG, Redmond HP. Analysis of differential gene expression in colorectal cancer and stroma using fluorescence-activated cell sorting purification. Br J Cancer 2009; 100:1452-64. [PMID: 19401702 PMCID: PMC2694425 DOI: 10.1038/sj.bjc.6604931] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Tumour stroma gene expression in biopsy specimens may obscure the expression of tumour parenchyma, hampering the predictive power of microarrays. We aimed to assess the utility of fluorescence-activated cell sorting (FACS) for generating cell populations for gene expression analysis and to compare the gene expression of FACS-purified tumour parenchyma to that of whole tumour biopsies. Single cell suspensions were generated from colorectal tumour biopsies and tumour parenchyma was separated using FACS. Fluorescence-activated cell sorting allowed reliable estimation and purification of cell populations, generating parenchymal purity above 90%. RNA from FACS-purified and corresponding whole tumour biopsies was hybridised to Affymetrix oligonucleotide microarrays. Whole tumour and parenchymal samples demonstrated differential gene expression, with 289 genes significantly overexpressed in the whole tumour, many of which were consistent with stromal gene expression (e.g., COL6A3, COL1A2, POSTN, TIMP2). Genes characteristic of colorectal carcinoma were overexpressed in the FACS-purified cells (e.g., HOX2D and RHOB). We found FACS to be a robust method for generating samples for gene expression analysis, allowing simultaneous assessment of parenchymal and stromal compartments. Gross stromal contamination may affect the interpretation of cancer gene expression microarray experiments, with implications for hypotheses generation and the stability of expression signatures used for predicting clinical outcomes.
Collapse
Affiliation(s)
- M J Smith
- Department of Academic Surgery, University College Cork, Cork, Ireland
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
56
|
Alfano RW, Leppla SH, Liu S, Bugge TH, Meininger CJ, Lairmore TC, Mulne AF, Davis SH, Duesbery NS, Frankel AE. Matrix metalloproteinase-activated anthrax lethal toxin inhibits endothelial invasion and neovasculature formation during in vitro morphogenesis. Mol Cancer Res 2009; 7:452-61. [PMID: 19372576 DOI: 10.1158/1541-7786.mcr-08-0451] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Solid tumor growth is dependent on angiogenesis, the formation of neovasculature from existing vessels. Endothelial activation of the extracellular signal-regulated kinase 1/2, c-jun NH(2)-terminal kinase, and p38 mitogen-activated protein kinase pathways is central to this process, and thus presents an attractive target for the development of angiogenesis inhibitors. Anthrax lethal toxin (LeTx) has potent catalytic mitogen-activated protein kinase inhibition activity. Preclinical studies showed that LeTx induced potent tumor growth inhibition via the inhibition of xenograft vascularization. However, LeTx receptors and the essential furin-like activating proteases are expressed in many normal tissues, potentially limiting the specificity of LeTx as an antitumor agent. To circumvent nonspecific LeTx activation and simultaneously enhance tumor vascular targeting, a substrate preferably cleaved by the gelatinases class of matrix metalloproteinases (MMP) was substituted for the furin LeTx activation site. In vivo efficacy studies showed that this MMP-activated LeTx inhibited tumor xenografts growth via the reduced migration of endothelial cells into the tumor parenchyma. Here we have expanded on these initial findings by showing that this MMP-activated LeTx reduces endothelial proangiogenic MMP expression, thus causing a diminished proteolytic capacity for extracellular matrix remodeling and endothelial differentiation into capillary networks. Additionally, our data suggest that inhibition of the c-jun NH(2)-terminal kinase and p38, but not extracellular signal-regulated kinase-1/2, pathways is significant in the antiangiogenic activity of the MMP-activated LeTx. Collectively, these results support the clinical development of the MMP-activated LeTx for the treatment of solid tumors.
Collapse
Affiliation(s)
- Randall W Alfano
- Cancer Research Institute of Scott and White, Temple, TX 76502, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
57
|
Vasil ML, Stonehouse MJ, Vasil AI, Wadsworth SJ, Goldfine H, Bolcome RE, Chan J. A complex extracellular sphingomyelinase of Pseudomonas aeruginosa inhibits angiogenesis by selective cytotoxicity to endothelial cells. PLoS Pathog 2009; 5:e1000420. [PMID: 19424430 PMCID: PMC2673038 DOI: 10.1371/journal.ppat.1000420] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2008] [Accepted: 04/08/2009] [Indexed: 11/19/2022] Open
Abstract
The hemolytic phospholipase C (PlcHR) expressed by Pseudomonas aeruginosa is the original member of a Phosphoesterase Superfamily, which includes phosphorylcholine-specific phospholipases C (PC-PLC) produced by frank and opportunistic pathogens. PlcHR, but not all its family members, is also a potent sphingomyelinase (SMase). Data presented herein indicate that picomolar (pM) concentrations of PlcHR are selectively lethal to endothelial cells (EC). An RGD motif of PlcHR contributes to this selectivity. Peptides containing an RGD motif (i.e., GRGDS), but not control peptides (i.e., GDGRS), block the effects of PlcHR on calcium signaling and cytotoxicity to EC. Moreover, RGD variants of PlcHR (e.g., RGE, KGD) are significantly reduced in their binding and toxicity, but retain the enzymatic activity of the wild type PlcHR. PlcHR also inhibits several EC-dependent in vitro assays (i.e., EC migration, EC invasion, and EC tubule formation), which represent key processes involved in angiogenesis (i.e., formation of new blood vessels from existing vasculature). Finally, the impact of PlcHR in an in vivo model of angiogenesis in transgenic zebrafish, and ones treated with an antisense morpholino to knock down a key blood cell regulator, were evaluated because in vitro assays cannot fully represent the complex processes of angiogenesis. As little as 2 ng/embryo of PlcHR was lethal to approximately 50% of EGFP-labeled EC at 6 h after injection of embryos at 48 hpf (hours post-fertilization). An active site mutant of PlcHR (Thr178Ala) exhibited 120-fold reduced inhibitory activity in the EC invasion assay, and 20 ng/embryo elicited no detectable inhibitory activity in the zebrafish model. Taken together, these observations are pertinent to the distinctive vasculitis and poor wound healing associated with P. aeruginosa sepsis and suggest that the potent antiangiogenic properties of PlcHR are worthy of further investigation for the treatment of diseases where angiogenesis contributes pathological conditions (e.g., vascularization of tumors, diabetic retinopathy).
Collapse
Affiliation(s)
- Michael L Vasil
- Department of Microbiology, University of Colorado Denver, Anschutz Medical Center, Aurora, Colorado, United States of America.
| | | | | | | | | | | | | |
Collapse
|
58
|
Moayeri M, Crown D, Dorward DW, Gardner D, Ward JM, Li Y, Cui X, Eichacker P, Leppla SH. The heart is an early target of anthrax lethal toxin in mice: a protective role for neuronal nitric oxide synthase (nNOS). PLoS Pathog 2009; 5:e1000456. [PMID: 19478875 PMCID: PMC2680977 DOI: 10.1371/journal.ppat.1000456] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Accepted: 04/29/2009] [Indexed: 01/04/2023] Open
Abstract
Anthrax lethal toxin (LT) induces vascular insufficiency in experimental animals through unknown mechanisms. In this study, we show that neuronal nitric oxide synthase (nNOS) deficiency in mice causes strikingly increased sensitivity to LT, while deficiencies in the two other NOS enzymes (iNOS and eNOS) have no effect on LT-mediated mortality. The increased sensitivity of nNOS-/- mice was independent of macrophage sensitivity to toxin, or cytokine responses, and could be replicated in nNOS-sufficient wild-type (WT) mice through pharmacological inhibition of the enzyme with 7-nitroindazole. Histopathological analyses showed that LT induced architectural changes in heart morphology of nNOS-/- mice, with rapid appearance of novel inter-fiber spaces but no associated apoptosis of cardiomyocytes. LT-treated WT mice had no histopathology observed at the light microscopy level. Electron microscopic analyses of LT-treated mice, however, revealed striking pathological changes in the hearts of both nNOS-/- and WT mice, varying only in severity and timing. Endothelial/capillary necrosis and degeneration, inter-myocyte edema, myofilament and mitochondrial degeneration, and altered sarcoplasmic reticulum cisternae were observed in both LT-treated WT and nNOS-/- mice. Furthermore, multiple biomarkers of cardiac injury (myoglobin, cardiac troponin-I, and heart fatty acid binding protein) were elevated in LT-treated mice very rapidly (by 6 h after LT injection) and reached concentrations rarely reported in mice. Cardiac protective nitrite therapy and allopurinol therapy did not have beneficial effects in LT-treated mice. Surprisingly, the potent nitric oxide scavenger, carboxy-PTIO, showed some protective effect against LT. Echocardiography on LT-treated mice indicated an average reduction in ejection fraction following LT treatment in both nNOS-/- and WT mice, indicative of decreased contractile function in the heart. We report the heart as an early target of LT in mice and discuss a protective role for nNOS against LT-mediated cardiac damage.
Collapse
Affiliation(s)
- Mahtab Moayeri
- Bacterial Toxins and Therapeutics Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Devorah Crown
- Bacterial Toxins and Therapeutics Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - David W. Dorward
- Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Don Gardner
- Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Jerrold M. Ward
- Infectious Diseases Pathogenesis Section, Comparative Medicine Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Yan Li
- Critical Care Medicine Department, National Institutes of Health Clinical Center, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Xizhong Cui
- Critical Care Medicine Department, National Institutes of Health Clinical Center, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Peter Eichacker
- Critical Care Medicine Department, National Institutes of Health Clinical Center, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Stephen H. Leppla
- Bacterial Toxins and Therapeutics Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| |
Collapse
|
59
|
Kristan KC, Viero G, Dalla Serra M, Macek P, Anderluh G. Molecular mechanism of pore formation by actinoporins. Toxicon 2009; 54:1125-34. [PMID: 19268680 DOI: 10.1016/j.toxicon.2009.02.026] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Actinoporins are effective pore-forming toxins produced by sea anemones. These extremely potent, basic 20 kDa proteins readily form pores in membranes that contain sphingomyelin. Much has been learned about the molecular basis of their pore-forming mechanism in recent years. Pore formation is a multi-step process that involves recognition of membrane sphingomyelin, firm binding to the membrane accompanied by the transfer of the N-terminal region to the lipid-water interface and finally pore formation after oligomerisation of three to four monomers. The final conductive pathway is formed by amphipathic alpha-helices, hence actinoporins are an important example of so-called alpha-helical pore-forming toxins. Actinoporins have become useful model proteins to study protein-membrane interactions, specific recognition of lipids in the membrane, and protein oligomerisation in the lipid milieu. Recent sequence and structural data of proteins similar to actinoporins indicate that they are not a unique family restricted to sea anemones as was long believed. An AF domain superfamily (abbreviated from actinoporin-like proteins and fungal fruit-body lectins) was defined and shown to contain members from three animal and two plant phyla. On the basis of functional properties of some members we hypothesise that AF domain proteins are peripheral membrane proteins. Finally, ability of actinoporins to form transmembrane pores has been exploited in some novel biomedical applications.
Collapse
Affiliation(s)
- Katarina Crnigoj Kristan
- Department of Biology, Biotechnical faculty, University of Ljubljana, Vecna pot 111, 1000 Ljubljana, Slovenia
| | | | | | | | | |
Collapse
|
60
|
Tejuca M, Anderluh G, Dalla Serra M. Sea anemone cytolysins as toxic components of immunotoxins. Toxicon 2009; 54:1206-14. [PMID: 19268683 DOI: 10.1016/j.toxicon.2009.02.025] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The use of membrane active toxins as toxic moieties in the construction of immunotoxins (ITs) is an attractive alternative to overcome some of the problems of classical ITs since these new conjugates are based in the use of a different mechanism of killing undesired cells. Pore-forming cytolysins from sea anemones were used in the construction of ITs targeted to different cell types including tumour cell lines and the parasite Giardia duodenalis. The results obtained support the feasibility of directing these cytolysins to the surface of the cancer cells or the parasite through their conjugation to monoclonal antibodies recognizing tumour-associated or parasite antigens, respectively. However the main problem with the IT constructed in this fashion is the lack of specificity associated with the toxin moiety. An approach designed to overcome this limitation was the construction of inactive cytolysin with built-in biological "trigger" that renders the toxin active in the presence of tumour-specific proteinases. This construction is considered as a proof of concept to demonstrate the feasibility of such activation systems in the construction of ITs based on pore-forming cytolysins from sea anemones with reduced unspecific activity. The future prospects of the use of the N-terminal region of actinoporins for construction of IT is also described.
Collapse
Affiliation(s)
- Mayra Tejuca
- Centro de Estudios de Proteínas y Departamento de Bioquímica, Facultad de Biologia, Universidad de La Habana, Calle 25 #455 e/ J e I, Vedado, Ciudad de La Habana, Cuba.
| | | | | |
Collapse
|
61
|
Alfano RW, Leppla SH, Liu S, Bugge TH, Herlyn M, Smalley KS, Bromberg-White JL, Duesbery NS, Frankel AE. Cytotoxicity of the matrix metalloproteinase-activated anthrax lethal toxin is dependent on gelatinase expression and B-RAF status in human melanoma cells. Mol Cancer Ther 2008; 7:1218-26. [PMID: 18483309 DOI: 10.1158/1535-7163.mct-08-0024] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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.
Collapse
Affiliation(s)
- Randall W Alfano
- Scott & White Cancer Research Institute Memorial Hospital, 5701 South Airport Road, Temple, TX 76502, USA
| | | | | | | | | | | | | | | | | |
Collapse
|