Endothelial p21(WAF1/CiP1) cell cycle inhibitor is down-regulated in breast cancer.

ABSTRACT

BACKGROUND: Tumor angiogenesis is considered a multi-pathway process, while p21(WAF1/CiP1) is a CDK inhibitor involved in cell division and survivaL Herein the tumor environment effect on endothelial p21(WAF1/Cip1) expression is examined. MATERIALS AND METHODS: The EA.hy 926 endothelial cell line and tumor-conditioned medium (TCM) from the MDA-MB-468 breast cancer cell line were used. Endothelial cells grown alone and in TCM were immunostained for p21(WAF1/Cip1) and analyzed by RT-PCR Forty-four cases of breast cancer and forty-three cases of normal breast tissue were immunostained for p21(WAF1/Cip1). RESULTS: Endothelial p21(WAF1/Cip1) is transcriptionally down-regulated under the influence of TCM. Moreover, it seems that breast cancer tumor endothelium does not express p21(WAF1/Cip1). CONCLUSION: P21(WAF1/Cip1) plays a major role in angiogenesis, since tumor cells seem to down-regulate endothelial p21(WAF1/Cip1), compared to endothelial cells grown in serum-free medium. The verification of the tissue culture experiment results by immunohistochemistry on tissue sections indicates p21(WAF1/Cip1) as a target of modern molecular therapy.