The vascular-targeting fusion toxin VEGF121/rGel inhibits the growth of orthotopic human bladder carcinoma tumors.
Vascular endothelial growth factor (VEGF) and its receptors (FLT-1 and KDR) are overexpressed by human bladder cancer cells and tumor endothelial cells, respectively. Strategies that target VEGF receptors hold promise as antiangiogenic therapeutic approaches to bladder cancer. A fusion protein of VEGF121 and the plant toxin gelonin (rGel) was constructed, expressed in bacteria, and purified to homogeneity. Cytotoxicity experiments of VEGF121/rGel on the highly metastatic 253J B-V human bladder cancer cell line demonstrated that the VEGF121/rGel does not specifically target these cells, whereas Western blot analysis showed no detectable expression of KDR. Treatment with VEGF121/rGel against orthotopically implanted 253J B-V xenografts in nude mice resulted in a significant suppression of bladder tumor growth (approximately 60% inhibition; P < .05) compared to controls. Immunohistochemistry studies of orthotopic 253J B-V tumors demonstrated that KDR is highly overexpressed in tumor vasculature. Immunofluorescence staining with antibodies to CD-31 (blood vessel endothelium) and rGel demonstrated a dramatic colocalization of the construct on tumor neovasculature. Treated tumors also displayed an increase in terminal deoxynucleotidyl transferase-mediated dUTP-biotin end labeling staining compared to controls. Thus, VEGF121/rGel inhibits the growth of human bladder cancer by cytotoxic effects directed against the tumor vascular supply and has significant potential as a novel antiangiogenic therapeutic against human bladder cancer.
Mohamedali
Khalid A
KA
Department of Experimental Therapeutics, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA.
Kedar
Daniel
D
Sweeney
Paul
P
Kamat
Ashish
A
Davis
Darren W
DW
Eve
Beryl Y
BY
Huang
Samuel
S
Thorpe
Philip E
PE
Dinney
Colin P
CP
Rosenblum
Michael G
MG
D000818:Animals; D001710:Biotin / Q000737:chemistry; D015153:Blotting, Western; D045744:Cell Line, Tumor; D018920:Coculture Techniques; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000378:metabolism; D005782:Gels / Q000737:chemistry*; D006801:Humans; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D008297:Male; D020714:Maximum Tolerated Dose; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008856:Microscopy, Fluorescence; D009362:Neoplasm Metastasis; D009368:Neoplasm Transplantation; D009389:Neovascularization, Pathologic; D010766:Phosphorylation; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000096:biosynthesis; D012313:RNA / Q000737:chemistry; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013552:Swine; D001749:Urinary Bladder Neoplasms / Q000378:metabolism* / Q000473:pathology; D042461:Vascular Endothelial Growth Factor A / Q000737:chemistry*
D005782:Gels; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D011993:Recombinant Fusion Proteins; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D012313:RNA; D001710:Biotin