In vitro and in vivo studies of a VEGF121/rGelonin chimeric fusion toxin targeting the neovasculature of solid tumors.
Vascular endothelial growth factor (VEGF) plays a key role in the growth and metastasis of solid tumors. We generated a fusion protein containing VEGF(121) linked by a flexible G(4)S tether to the toxin gelonin (rGel) and expressed this as a soluble protein in bacteria. Purified VEGF(121)/rGel migrated as an 84-kDa homodimer under nonreducing conditions. VEGF(121)/rGel bound to purified, immobilized Flk-1, and the binding was competed by VEGF(121). Both VEGF(121)/rGel and VEGF(121) stimulated cellular kinase insert domain receptor (KDR) phosphorylation. The VEGF(121)/rGel fusion construct was highly cytotoxic to endothelial cells overexpressing the KDR/Flk-1 receptor. The IC(50) of the construct on dividing endothelial cells expressing 10(5) or more KDR/Flk-1 receptors per cell was 0.5-1 nM, as compared with 300 nM for rGel itself. Dividing endothelial cells overexpressing KDR were approximately 60-fold more sensitive to VEGF(121)/rGel than were nondividing cells. Endothelial cells overexpressing FLT-1 were not sensitive to the fusion protein. Human melanoma (A-375) or human prostate (PC-3) xenografts treated with the fusion construct demonstrated a reduction in tumor volume to 16% of untreated controls. The fusion construct localized selectively to PC-3 tumor vessels and caused thrombotic damage to tumor vessels with extravasation of red blood cells into the tumor bed. These studies demonstrate the successful use of VEGF(121)/rGel fusion construct for the targeted destruction of tumor vasculature in vivo.
Veenendaal
Liesbeth M
LM
Immunopharmacology and Targeted Therapy Section, Department of Bioimmunotherapy, Univ. of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030-4009, USA.
Jin
Hangqing
H
Ran
Sophia
S
Cheung
Lawrence
L
Navone
Nora
N
Marks
John W
JW
Waltenberger
Johannes
J
Thorpe
Philip
P
Rosenblum
Michael G
MG
D020533:Angiogenesis Inhibitors / Q000627:therapeutic use*; D000818:Animals; D001013:Aorta, Thoracic; D001483:Base Sequence; D002417:Cattle; D002470:Cell Survival / Q000187:drug effects*; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology*; D017931:DNA Primers; D016228:Endothelial Growth Factors; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D008222:Lymphokines; D051379:Mice; D010940:Plant Proteins; D016133:Polymerase Chain Reaction; D011817:Rabbits; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D017978:Receptors, Growth Factor / Q000378:metabolism; D040262:Receptors, Vascular Endothelial Growth Factor; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification / Q000627:therapeutic use*; D012156:Reticulocytes / Q000378:metabolism; D054789:Ribosome Inactivating Proteins, Type 1; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D020533:Angiogenesis Inhibitors; D017931:DNA Primers; D016228:Endothelial Growth Factors; D008222:Lymphokines; D010940:Plant Proteins; D017978:Receptors, Growth Factor; D011993:Recombinant Fusion Proteins; D054789:Ribosome Inactivating Proteins, Type 1; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; C025674:GEL protein, Gelonium multiflorum; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor