Angiogenesis gene expression profiling in xenograft models to study cellular interactions

The present study describes a method to simultaneously obtain the angiogenic expression profile in tumor cells and vascular cells of a single tumor. Human- and mouse-specific primers were used for quantitative real-time RT-PCR to determine the expression of vascular endothelial growth factors A, B, C, and D, vascular endothelial growth factor receptors 1, 2, and 3, neuropilin 1 and 2, angiopoietin 1, 2, 3/4, tyrosine kinase receptors 1 and 2, basic fibroblast growth factor (bFGF) in xenograft tumors obtained by injection of human ovarian carcinoma cells in nude mice. In addition, the effect of treatment with anginex and taxol on the expression profile was analyzed. Most factors were expressed higher in vascular cells as compared to tumor cells. In response to treatment, tumor cells significantly upregulated bFGF expression and downregulated VEGF receptor expression. This was accompanied by downregulation of VEGF-B and -D, and upregulation of angiopoietin-3 as well as angiopoetin receptors in nontumor cells. In conclusion, real-time qRT-PCR combined with xenograft tumor models presents a sensitive method to monitor angiogenesis and to analyze interactions between tumor cells and nontumor cells in vivo. The approach can be applied to different research fields in which xenograft models are used.