Bostad M, Berg K, Hogset A, Skarpen E, Stenmark H, Selbo PK (2013) Photochemical internalization (PCI) of immunotoxins targeting CD133 is specific and highly potent at femtomolar levels in cells with cancer stem cell properties. J Control Release 168(3):317-326. doi: 10.1016/j.jconrel.2013.03.023
Summary: Targeted therapies for cancer can be trapped in the lysosome and compartmentalized away from the target. Photochemical internalization is a method to increase the efficacy of these compounds by releasing the therapeutic portion of the molecule from the endocytic vesicles to the cytosol by the use of light. The authors demonstrate this method on cells expressing the cancer stem cell marker CD133. Biotinylated antibodies against CD133 were combined with Streptavidin-ZAP (Cat. #IT-27) and applied to cell lines.
Ben-David U, Nudel N, Benvenisty N (2013) Immunologic and chemical targeting of the tight-junction protein Claudin-6 eliminates tumorigenic human pluripotent stem cells. Nat Commun 4:1992. doi: 10.1038/ncomms2992 PMID: 23778593
Objective: To identify a pluripotent cell specific surface marker and develop strategies to selectively eliminate tumorigenic human pluripotent stem cells (hPSCs) from mixed cell populations.
Summary: Claudin-6 (CLDN-6) was identified as a specific surface marker of hPSCs. Targeted elimination using CLDN-6 immunotoxins or sorting, effectively reduced teratoma formation, improving the safety of stem cell–based therapies.
Usage: Fab-ZAP Mouse (IT-48) and a primary anti-CLDN-6 antibody was applied at various concentrations to selectively eliminate CLDN-6–positive hPSCs.
Burgos-Ojeda D, McLean K, Bai S, Pulaski H, Gong Y, Silva I, Skorecki K, Tzukerman M, Buckanovich RJ (2013) A novel model for evaluating therapies targeting human tumor vasculature and human cancer stem-like cells. Cancer Res 73(12):3555-3565. doi: 10.1158/0008-5472.CAN-12-2845
Objective: To evaluate tumor vascular markers (TVM) expression in a human embryonic stem cell–derived teratoma (hESCT) tumor model previously shown to have human vessels.
Summary: The model tested represents a useful tool to test anti-human TVM therapy and evaluate in vivo human CSC tumor biology.
Usage: In vitro – Anti-THY1-SAP (biotinylated Anti-THY1 mixed equimolar with Streptavidin-ZAP) was incubated with mesenchymal stem cells (MSC); resulting in statistically significant MSC death. In vivo – Anti-THY1-SAP or control (Rat IgG-SAP) was administered intravenously. Treated ovarian tumors showed delayed growth and significant reduction in central tumor viability.
Yamazaki CM, Nakase I, Endo H, Kishimoto S, Mashiyama Y, Masuda R, Futaki S, Koide T (2013) Collagen-like cell-penetrating peptides. Angew Chem Int Ed Engl 52(21):5497-5500. doi: 10.1002/anie.201301266
Objective: To overcome drawbacks of cell-penetrating peptide (CPP)-conjugated forms, namely instability against attack by proteases, and binding to serum proteins that lowers the availability of the CPP to target cells.
Summary: Complexes were prepared by combining biotinylated CPPs with Streptavidin-ZAP to evaluate the impact of utilizing a rigid collagen-like triple-helical scaffold to improve CPP performance. There was low adsorption onto serum proteins and triple-helical CPPs are extremely stable in animal serum. Such unique properties are expected to be advantageous to long-term applications in cell culture systems and to in vivo drug delivery.
Usage: Biotinylated CPPs were interacted with Streptavidin-ZAP (SA-ZAP); IT-27: Streptavidin-ZAP
Stratford EW, Bostad M, Castro R, Skarpen E, Berg K, Hogset A, Myklebost O, Selbo PK (2013) Photochemical internalization of CD133-targeting immunotoxins efficiently depletes sarcoma cells with stem-like properties and reduces tumorigenicity. Biochim Biophys Acta 1830(8):4235-4243. doi: 10.1016/j.bbagen.2013.04.033
Summary: In this work the authors used photochemical internalization (PCI) to facilitate local cytosolic toxin release from various biotinylated-anti-CD133 antibodies coupled with Streptavidin-ZAP (Cat. #IT-27) in SW872 cells. This technique demonstrates potential for non-invasive sarcoma therapy.
How can I target B-cells? Which secondary conjugate should I use?
ATS makes secondary conjugates that use your primary antibody to target cells for elimination. Just mix your primary antibody with a secondary antibody conjugated to the ribosome-inactivating protein, Saporin, to screen your antibodies. The cells targeted by your primary antibody are eliminated.
Recognizes whole IgG
Hum-ZAP (Cat. #IT-22) is made with a bivalent secondary antibody that recognizes whole IgG. B-Cells have endogenous IgGs.
Fab-ZAP (Cat. #IT-51) is made with a monovalent secondary antibody that recognizes whole IgG. B-Cells have endogenous IgGs.
Recognizes Fc region
FabFc-ZAP (Cat. #IT-65) is made with a monovalent secondary antibody that recognizes ONLY the FC portion of IgG.
Daniotti JL (2013) Featured Article: Antibodies to glycosphingolipids: An attractive tool for targeted delivery of cytotoxic agents to tumor cells. Targeting Trends 14(2)
Hernandez L, Flenker K, Hernandez F, Klingelhutz A, McNamara J, Giangrande P (2013) Methods for evaluating cell-specific, cell-internalizing RNA aptamers. Pharmaceuticals (Basel) 6:295-319. doi: 10.3390/ph6030295
Objective: Isolate aptamers that internalize upon binding to their cognate receptor on the cell surface
Summary: Among the methods used to characterize aptamers that internalize is a way to monitor for cytoplasmic delivery using the ribosome inactivating protein-based (RNA-RIP) assay. Biotin-labeled A9g was conjugated to streptavidin-modified saporin (streptavidin-ZAP). First, it was verified that conjugation of biotinylated aptamer to Streptavidin-ZAP (A9g-SAP) did not affect the inhibitory effect of the aptamer. Next, the effect was examined of A9g-SAP on PC3(PSMA+) and PC3(PSMA-) cells. Cells were treated with varying amounts of aptamer-saporin conjugate for 72 h at 37°C and then an assay was performed to determine potential cytotoxicity of the conjugate. Results confirm that A9g is internalized preferentially into target cells and that A9g is efficiently accessing the cytoplasm of target cells possibly through a mechanism of endosomal escape, resulting in inhibition of protein synthesis and ultimate cell-death. FGF-SAP was used as a control.
Rust S, Guillard S, Sachsenmeier K, Hay C, Davidson M, Karlsson A, Karlsson R, Brand E, Lowne D, Elvin J, Flynn M, Kurosawa G, Hollingsworth R, Jermutus L, Minter R (2013) Combining phenotypic and proteomic approaches to identify membrane targets in a ‘triple negative’ breast cancer cell type. Mol Cancer 12:11. doi: 10.1186/1476-4598-12-11
Summary: The authors investigated a phenotypic antibody screening technique, in which antibodies are selected by function rather than target specificity. One facet of the screening procedure for hybridomas generated using a cancer cell line as antigen was the use of Mab-ZAP (Cat. #IT-04) to assess cell binding and internalization.
Ren C, Luan L, Wui-Man Lau B, Huang X, Yang J, Zhou Y, Wu X, Gao J, Pickard GE, So KF, Pu M (2013) Direct retino-raphe projection alters serotonergic tone and affective behavior. Neuropsychopharmacology 38(7):1163-1175. doi: 10.1038/npp.2013.35
Summary: Although recent work has shown that some intrinsically photosensitive retinal ganglion cells (ipRGCs) are responsible for processing nonimage-forming visual functions, it is unclear whether the ipRGCs or conventional RGCs modulate affective behavior. The authors injected 2 μg of melanopsin-SAP (Cat. #IT-44) into each eye of gerbils, or biotinylated CTB monoclonal antibody coupled to Streptavidin-ZAP (Cat. #IT-27). The data suggest that retino-raphe signals modulate dorsal raphe nucleus serotonergic tone and affective behavior.
