Tumor progression and angiogenesis are intimately related. To understand the interrelationship between these two processes, real-time imaging can make a major contribution. In this report, fluorescent
protein imaging (FPI) and magnetic resonance imaging (MRI) were utilized to demonstrate the effects of
selenium on
tumor progression and angiogenesis in an orthotopic model of human
colon cancer. GEO (well-differentiated human colon
carcinoma) cells transfected with
green fluorescent protein (GFP) were implanted orthotopically into the colon of athymic nude mice. Beginning at five days post implantation, whole-body FPI was performed to monitor
tumor growth in vivo. Upon successful visualization of
tumor growth by FPI, animals were randomly assigned to either a control group or a treatment group. Treatment consisted of daily
oral administration of the organoselenium compound,
methyl-selenocysteine (MSC; 0.2 mg/day × five weeks). Dynamic contrast-enhanced MRI was performed to examine the change in
tumor blood volume following treatment. CD31 immunostaining of
tumor sections was also performed to quantify microvessel density (MVD). While T1- and T2-weighted MRI provided adequate contrast and volumetric assessment of GEO
tumor growth, GFP imaging allowed for high-throughput visualization of
tumor progression in vivo.
Selenium treatment resulted in a significant reduction in blood volume and microvessel density of GEO
tumors. A significant inhibition of
tumor growth was also observed in
selenium-treated animals compared to untreated control animals. Together, these results highlight the usefulness of multimodal imaging approaches to demonstrate antitumor and anti-angiogenesis efficacy and the promise of
selenium treatment of
colon cancer.