TY - JOUR
T1 - Mechanistic studies of a novel, human fusion toxin composed of vascular endothelial growth factor (VEGF)121and the serine protease granzyme B
T2 - Directed apoptotic events in vascular endothelial cells
AU - Liu, Yuying
AU - Cheung, Lawrence H.
AU - Thorpe, Philip
AU - Rosenblum, Michael G.
N1 - Copyright:
Copyright 2013 Elsevier B.V., All rights reserved.
PY - 2003/10
Y1 - 2003/10
N2 - The serine protease granzyme B (GrB; 25 kDa) is capable of inducing apoptosis through both caspase-dependent and caspase-independent mechanisms. We designed a novel vascular-targeting fusion construct designated as GrB/vascular endothelial growth factor (VEGF)121, which is composed of a non-heparin-binding isoform of VEGF and the proapoptotic pathway enzyme GrB fused via a short, flexible tether (G4S). The chimeric fusion gene was then cloned into a bacterial vector, and the protein was expressed in Escherichia coli and purified by nickel-NTA metal affinity chromatography. Western blotting confirmed incorporation of both VEGF121 and GrB proteins into the construct. GrB/VEGF121 specifically bound (ELISA) to porcine aortic endothelial (PAE)/FLK-1 cells overexpressing the FLK-1/KDR receptor but not to cells overexpressing the FLT-1 receptor. Immunofluoresence studies showed that the GrB moiety of GrB/VEGF121 was delivered efficiently and rapidly into the cytosol of PAE/FLK-1 cells but not into that of PAE/FLT-1 cells after 4 h treatment with GrB/VEGF121. Treatment of cells with GrB/VEGF121 showed that the IC50 was ∼10 nM against PAE/FLK-1 cells; however, there were no cytotoxic effects observed on PAE/FLT-1 cells at doses up to 200 nM. GrB/VEGF121 induced apoptotic events specifically on PAE/FLK-1 as assessed by terminal deoxynucleotidyl transferase-mediated nick end labeling assay, DNA laddering, and cytochrome c release from mitochondria. In addition, the fusion construct mediated the cleavage of caspase-8, caspase-3, and poly(ADP-ribose) polymerase in target endothelial cells within 4 h after treatment. In conclusion, delivery of the human proapoptotic pathway enzyme GrB to tumor vascular endothelial cells or to tumor cells may have significant therapeutic potential and represents a potent new class of targeted therapeutic agents with a unique mechanism of action.
AB - The serine protease granzyme B (GrB; 25 kDa) is capable of inducing apoptosis through both caspase-dependent and caspase-independent mechanisms. We designed a novel vascular-targeting fusion construct designated as GrB/vascular endothelial growth factor (VEGF)121, which is composed of a non-heparin-binding isoform of VEGF and the proapoptotic pathway enzyme GrB fused via a short, flexible tether (G4S). The chimeric fusion gene was then cloned into a bacterial vector, and the protein was expressed in Escherichia coli and purified by nickel-NTA metal affinity chromatography. Western blotting confirmed incorporation of both VEGF121 and GrB proteins into the construct. GrB/VEGF121 specifically bound (ELISA) to porcine aortic endothelial (PAE)/FLK-1 cells overexpressing the FLK-1/KDR receptor but not to cells overexpressing the FLT-1 receptor. Immunofluoresence studies showed that the GrB moiety of GrB/VEGF121 was delivered efficiently and rapidly into the cytosol of PAE/FLK-1 cells but not into that of PAE/FLT-1 cells after 4 h treatment with GrB/VEGF121. Treatment of cells with GrB/VEGF121 showed that the IC50 was ∼10 nM against PAE/FLK-1 cells; however, there were no cytotoxic effects observed on PAE/FLT-1 cells at doses up to 200 nM. GrB/VEGF121 induced apoptotic events specifically on PAE/FLK-1 as assessed by terminal deoxynucleotidyl transferase-mediated nick end labeling assay, DNA laddering, and cytochrome c release from mitochondria. In addition, the fusion construct mediated the cleavage of caspase-8, caspase-3, and poly(ADP-ribose) polymerase in target endothelial cells within 4 h after treatment. In conclusion, delivery of the human proapoptotic pathway enzyme GrB to tumor vascular endothelial cells or to tumor cells may have significant therapeutic potential and represents a potent new class of targeted therapeutic agents with a unique mechanism of action.
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M3 - Article
C2 - 14578460
AN - SCOPUS:1642290611
SN - 1535-7163
VL - 2
SP - 949
EP - 959
JO - Molecular Cancer Therapeutics
JF - Molecular Cancer Therapeutics
IS - 10
ER -