Metastasis correlates with production of vascular endothelial growth factor in a murine model of human Wilms' tumor.

BACKGROUND/PURPOSE: The growth and spread of solid tumors are critically dependent on the induction of angiogenesis. We hypothesized that vascular endothelial growth factor (VEGF) would be detected in Wilms' tumors, and that both growth and metastasis would parallel VEGF levels in a murine model.

METHODS

Primary tumors were established in the right kidneys of nude mice (n = 21). Mice were killed at 3, 4.5, or 6 weeks. Tumor-bearing and control kidneys were subjected to enzyme-linked immunosorbent assay (ELISA) for VEGF. Representative sections were assessed by histology and immunohistochemistry. Lungs were examined for metastases. Clinical specimens of Wilms' tumor (n = 12) also were assayed for VEGF.

RESULTS

The authors detected VEGF by ELISA with increasing frequency, and in increasing quantity, as experimental Wilms' tumors were grown over time. Immunohistochemistry demonstrated accumulation of VEGF in areas of viable tumor. Lung metastases occurred in 8 of 10 animals with VEGF-positive tumors, but in only 3 of 11 animals with VEGF-negative tumors, an association that was statistically significant. VEGF was found in 10 of 12 clinical Wilms' tumor specimens tested.

CONCLUSIONS

VEGF is present in both clinical and experimental Wilms' tumors. In a murine model, absolute VEGF levels increase as primary tumors grow, and VEGF production is significantly associated with tumor metastasis.