In vivo assessment of antiangiogenic activity of SU6668 in an experimental colon carcinoma model.
OBJECTIVE
The purpose of this research was to assess in vivo by dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) the antiangiogenic effect of SU6668, an oral, small molecule inhibitor of the angiogenic receptor tyrosine kinases vascular endothelial growth factor receptor 2 (Flk-1/KDR), platelet-derived growth factor receptor, and fibroblast growth factor receptor 1.


METHODS
A s.c. tumor model of HT29 human colon carcinoma in athymic mice was used. DCE-MRI with a macromolecular contrast agent was used to measure transendothelial permeability and fractional plasma volume, accepted surrogate markers of tumor angiogenesis. CD31 immunohistochemical staining was used for assessing microvessels density and vessels area. Experiments were performed after 24 h, and 3, 7, and 14 days of treatment.


RESULTS
DCE-MRI clearly detected the early effect (after 24 h of treatment) of SU6668 on tumor vasculature as a 51% and 26% decrease in the average vessel permeability measured in the tumor rim and core (respectively). A substantial decrease was also observed in average fractional plasma volume in the rim (59%) and core (35%) of the tumor. Histological results confirmed magnetic resonance imaging findings. After 3, 7, and 14 days of treatment, postcontrast magnetic resonant images presented a thin strip of strongly enhanced tissue at the tumor periphery; histology examination showed that this hyperenhanced ring corresponded to strongly vascularized tissue adjacent but external to the tumor. Histology also revealed a strong decrease in the thickness of peripheral viable tissue, with a greatly reduced vessel count. SU6668 greatly inhibited tumor growth, with 60% inhibition at 14 days of treatment.


CONCLUSIONS
DCE-MRI detected in vivo the antiangiogenic efficacy of SU6668.
Marzola
Pasquina
P
Dipartimento di Scienze Morfologico-Biomediche, Sezione di Anatomia ed Istologia, Università di Verona, Verona, Italy. pasquina.marzola@univr.it
Degrassi
Anna
A
Calderan
Laura
L
Farace
Paolo
P
Crescimanno
Caterina
C
Nicolato
Elena
E
Giusti
Anna
A
Pesenti
Enrico
E
Terron
Andrea
A
Sbarbati
Andrea
A
Abrams
Tinya
T
Murray
Lesley
L
Osculati
Francesco
F
D020533:Angiogenesis Inhibitors / Q000494:pharmacology*; D000818:Animals; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D003287:Contrast Media / Q000494:pharmacology; D006801:Humans; D007150:Immunohistochemistry; D007211:Indoles / Q000494:pharmacology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051379:Mice; D008819:Mice, Nude; D015233:Models, Statistical; D009368:Neoplasm Transplantation; D009389:Neovascularization, Pathologic; D000078183:Oxindoles; D010539:Permeability; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000096:biosynthesis; D011422:Propionates; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011758:Pyrroles / Q000494:pharmacology*; D013997:Time Factors
D020533:Angiogenesis Inhibitors; D003287:Contrast Media; D007211:Indoles; D000078183:Oxindoles; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D011422:Propionates; D011758:Pyrroles; C412603:orantinib; D011505:Protein-Tyrosine Kinases