Expression of endothelial PDGF receptors alpha and beta in breast cancer: up-regulation of endothelial PDGF receptor beta.

The PDGF pathway is essential in tumor angiogenesis. Although the expression of the PDGF receptors has been excessively studied on breast cancer cells, few studies exist on PDGFR expression on the tumor endothelial cells. In the present study, it is investigated whether endothelial PDGF receptors' expression is altered in breast cancer. Endothelial PDGFRalpha and beta expression was initially studied under the influence of tumor conditioned medium derived from a breast cancer cell line. Following tissue culture experiments the endothelial expression of both receptors was studied on formalin-fixed paraffin-embedded tissue sections of normal breast and breast cancer specimens. The tissue culture experiment revealed a possible up-regulation of endothelial PDGFRbeta by breast cancer environment. Immunohistochemistry verified the result since 69.7% of the breast cancer sections were positive for PDGFRbeta compared to 43.3% of normal breast sections (p<0.05). No statistical difference was revealed by studying PDGFRalpha expression. In conclusion, our findings support the thesis of possible anti-PDGFRbeta anti-angiogenic therapy, in cases of endothelial PDGFRbeta-expressing breast cancer.