Serum vascular endothelial growth factor (VEGF) levels correlate with number and location of micrometastases in a murine model of uveal melanoma

BACKGROUND A preliminary animal study was performed to determine if hepatic micrometastases from uveal melanoma secrete vascular endothelial growth factor (VEGF) that is measurable in serum. METHODS We analysed the serum of a C57Bl/6 mouse model of uveal melanoma (n=10) at days 4, 7, 14 and 21 post-inoculation for VEGF levels. We compared the serum VEGF levels with the number and location of hepatic micrometastases and their respective expression of VEGF mRNA. RESULTS Serum VEGF levels rose after inoculation of C57Bl/6 mice eyes with B16LS9 cutaneous melanoma cells. Beginning on day 14 there was a statistically significant (p<0.05) increase in VEGF levels, rising to an average peak level of 37.985 pg/ml at day 21. Peak serum VEGF levels correlated with the total number of hepatic micrometastases (R=0.444) and there was moderate correlation of peak VEGF serum levels with micrometastases in more hypoxic locations (R=0.572). VEGF mRNA expression by micrometastases was highest in the most hypoxic regions of the hepatic lobule. CONCLUSIONS Hepatic micrometastastic melanoma arising in a mouse model of ocular melanoma secretes VEGF. The number and location of the micrometastases correlate with serum VEGF levels.