Suppression of breast cancer metastasis through the inhibition of VEGF-mediated tumor angiogenesis.

One of the major causes of failure in the treatment of breast cancer is the occurrence of metastasis, the spreading of the primary tumor to distant organs. It is thus important to intervene at a key step of metastatic process, such as angiogenesis, for effective breast cancer treatment. Vascular endothelial growth factor (VEGF) plays a pivotal role in tumor angiogenesis. Because degree of tumor malignancy directly correlates with the expression of VEGF but inversely correlates with the expression of tumor suppressor gene p16, we examined whether restoration of p16 in breast cancer cells that lack p16 expression would modulate VEGF expression, and if so, how are the effects of p16 expression on tumor angiogenesis and metastasis. To facilitate induction of p16 expression, a recombinant adenovirus expressing p16 (AdRSVp16) was used to transduce breast cancer cell lines MDA-MB-231 and JygMC(A). This study showed that adenoviral-mediated p16 expression downregulated VEGF gene expression in breast cancer cells, inhibited breast cancer cell-induced angiogenesis, and suppressed breast tumor metastasis in a spontaneous metastasis model in mice. Moreover, the mechanism of how p16 regulates VEGF expression is also investigated.