Wiedlocha A, Haugsten EM, Zakrzewska M (2021) Roles of the FGF-FGFR signaling system in cancer development and inflammation. Cells 10(9):2231. doi: 10.3390/cells10092231 PMID: 34571880

Objective: To highlight the latest advances in understanding the role of the FGF-FGFR signaling system in the development of neoplastic diseases and in the induction and maintenance of inflammation and its sequelae.

Related Products: FGF-SAP (Cat. #IT-38)

Vikan AK, Kostas M, Haugsten EM, Selbo PK, Wesche J (2021) Efficacy and selectivity of FGF2-saporin cytosolically delivered by PCI in cells overexpressing FGFR1. Cells 10(6):1476. doi: 10.3390/cells10061476

Summary: Fibroblast growth factor receptors (FGFRs) have become an attractive target in cancer research and therapy due to their implication in several cancers. The authors evaluated the efficacy and selectivity of PCI of FGF2-saporin (FGF-SAP) in cells overexpressing FGFR1. The authors conclude that to prevent off-target effects of FGF-based toxins, it will be necessary to circumvent binding to HSPGs, for example by mutating the binding site of FGF2 to HSPGs.

Related Products: FGF-SAP (Cat. #IT-38)

Esko JD, Stanley P (2017) Glycosylation mutants of cultured mammalian cells. (eds. Varki A, Cummings RD, Esko JD, Stanley P, Hart GW, Aebi M, Darvill AG, Kinoshita T, Packer NH, Prestegard JH, Schnaar RL, Seeberger PH). In: Essentials of Glycobiology Chapter 49. Cold Spring Harbor (NY): Cold Spring Harbor Laboratory Press doi: 10.1101/glycobiology.3e.049

Related Products: FGF-SAP (Cat. #IT-38)

Dickey D, Thomas G, Dassie J, Giangrande P (2016) Method for confirming cytoplaintratumoral anti-HuD immunotoxinsmic delivery of RNA aptamers. (eds. Shum K, Rossi J). In: SiRNA Delivery Methods. Methods in Molecular Biology. 1364:209-217. Humana Press, New York, NY. doi: 10.1007/978-1-4939-3112-5_17

Objective: To describe a functional assay (RIP assay) to confirm cellular uptake and subsequent cytoplasmic release of an RNA aptamer which binds to a cell surface receptor expressed on prostate cancer cells (PSMA).

Summary: This publication details an in vitro functional assay to confirm that the aptamer retains function following conjugation to saporin and describe a cellular assay to measure aptamer-mediated saporin-induced cytotoxicity.

Usage: The folded biotinylated aptamer was mixed at a 1:4 molar ratio of Streptavidin-ZAP, confirmed by agarose gel, a PSMA enzymatic activity (NAALADase) assay performed. FGF-SAP was used as a control.

Related Products: Streptavidin-ZAP (Cat. #IT-27), FGF-SAP (Cat. #IT-38)

Can you comment on the mechanism by which the SAP toxin is cleaved off from the antibody? Your website indicates that the cleavage occurs in the endosome. I just want to verify that it is not cleaved in the lysosome.

From what we have gathered, there is a great probability that something gets broken in the endosome. We know this from the peptide ligand toxins that bind to GPCRs. They would be rapidly returned to the cell surface through receptor recycling if there wasn’t some sort of cleavage. In the case of FGF-SAP (Cat. #IT-38) , e.g., we know that FGF is extensively degraded in the endosome through proteolytic degradation (Lappi et al, 1994). There is occasionally a disulfide linker between the toxin and antibody, but there is some controversy that this is cleaved: many say yes, some say no, mainly because the redox potential is not sufficient. This would ignore the presence of thiol reductase enzymes. The single chain antibody fusion protein-toxins are quite toxic. The linkage there is clearly through peptide bonds (they are fusion proteins) so the easiest response to this question is that there is proteolytic degradation. Since saporin is tremendously resistant to proteases, it can’t be stopped.

Lappi DA, Ying W, Barthelemy I, Martineau D, Prieto I, Benatti L, Soria M, Baird A (1994) Expression and activities of a recombinant basic fibroblast growth factor-saporin fusion protein. J Biol Chem 269(17):12552-12558. doi: PMID: 8175664

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.

Related Products: Streptavidin-ZAP (Cat. #IT-27), FGF-SAP (Cat. #IT-38)

Liao D, Lin PH, Yao Q, Chen C (2008) Vascular smooth cell proliferation in perfusion culture of porcine carotid arteries. Biochem Biophys Res Commun 372(4):668-673. doi: 10.1016/j.bbrc.2008.05.117

Summary: Basic fibroblast growth factor is highly effective in stimulating smooth muscle cell (SMC) proliferation. The authors used FGF-SAP (Cat. #IT-38) to help characterize a model of vascular SMC proliferation with porcine carotid arteries. Arteries isolated from pigs were cultured under several different conditions, one of which included FGF-SAP at a concentration of 0.4 nM. In all cases the arteries maintained viability for up to 96 hours. SMC proliferation was drastically reduced in the arteries treated with FGF-SAP. [Note, FGF-SAP is not ATS.]

Related Products: FGF-SAP (Cat. #IT-38)

Davol P, Frackelton AR Jr (1996) The mitotoxin, basic fibroblast growth factor-saporin, effectively targets human prostatic carcinoma in an animal model. J Urol 156(3):1174-1179. doi: 10.1016/s0022-5347(01)65745-8

Related Products: FGF-SAP (Cat. #IT-38)

Davol P, Beitz JG, Mohler M, Ying W, Cook J, Lappi DA, Frackelton AR Jr (1995) Saporin toxins directed to basic fibroblast growth factor receptors effectively target human ovarian teratocarcinoma in an animal model. Cancer 76(1):79-85. doi: 10.1002/1097-0142(19950701)76:1<79::aid-cncr2820760111>3.0.co;2-g PMID: 8630880

Related Products: FGF-SAP (Cat. #IT-38)

Lappi DA, Ying W, Barthelemy I, Martineau D, Prieto I, Benatti L, Soria M, Baird A (1994) Expression and activities of a recombinant basic fibroblast growth factor-saporin fusion protein. J Biol Chem 269(17):12552-12558. PMID: 8175664

Related Products: FGF-SAP (Cat. #IT-38)