Gene expression of vascular endothelial growth factor in giant cell tumors of bone

The production of vascular endothelial growth factors (VEGF), a major cause of neoangiogenesis, is a prerequisite for tumor growth and invasion. VEGF have also been shown to be important for the formation of osteoclasts. Because giant cell tumors of bone (GCT) are frequently hypervascular and have the ability to recruit macrophages and multinucleated osteoclast-like giant cells, we evaluated the levels of VEGF gene transcript in several of these tumors using Northern blot analyses, semiquantitative reverse transcription polymerase chain reaction (RT-PCR), fluorescence in situ hybridization (FISH), and immunohistochemistry. Our results showed that three major isoforms of VEGF (121, 165, and 189) were expressed in all cases of GCT investigated, with isoform 121 transcripts the most abundant. By both FISH and immunohistochemistry, we have shown that VEGF was present in spindle-shaped stromal-like tumor cells, round macrophage-like cells, and osteoclast-like multinucleate giant cells. Moreover, we have shown that the levels of VEGF gene expression but not microvessel density correlated with Enneking's clinical stage of GCT. There were higher levels of VEGF gene expression in stage III GCT than in stage I/II GCT (P < .0357). In conclusion, our results indicate that overexpression of VEGF may be associated with the advanced stage of the neoplasm.