LGALS3BP, lectin galactoside-binding soluble 3 binding protein, induces vascular endothelial growth factor in human breast cancer cells and promotes angiogenesis

Elevated serum or tissue levels of lectin galactoside-binding soluble 3 binding protein (LGALS3BP) have been associated with short survival and development of metastasis in a variety of human cancers. However, the role of LGALS3BP, particularly in the context of tumor-host relationships, is still missing. Here, we show that LGALS3BP knockdown in MDA-MB-231 human breast cancer cells leads to a decreased adhesion to fibronectin, a reduced transendothelial migration and, more importantly, a reduced expression of vascular endothelial growth factor (VEGF). Production of VEGF, that was restored by exposure of silenced cells to recombinant LGALS3BP, required an intact PI3k/Akt signaling. Furthermore, we show that LGALS3BP was able to directly stimulate HUVEC tubulogenesis in a VEGF-independent, galectin-3-dependent manner. Immunohistochemical analysis of human breast cancer tissues revealed a correlation among LGALS3BP expression, VEGF expression, and blood vessel density. We propose that in addition to its prometastatic role, LGALS3BP secreted by breast cancer cells functions critically as a pro-angiogenic factor through a dual mechanism, i.e by induction of tumor VEGF and stimulation of endothelial cell tubulogenesis.