Data from Vascular Endothelial Cadherin Promotes Breast Cancer Progression via Transforming Growth Factor β Signaling

Epithelial-to-mesenchymal transition (EMT) is an important event during carcinoma progression and leads to increased tumor cell malignancy. Here, we show that vascular endothelial (VE)-cadherin is induced during EMT in mammary tumor cells and is aberrantly expressed in invasive human breast carcinomas. VE-cadherin enhanced the capacity of fibroblastoid tumor cells to proliferate, form cord-like invasive structures, and adhere to endothelial cells, characteristics that are key contributors to their increased malignancy and metastatic potential. Consistently, VE-cadherin expression in malignant fibroblastoid tumor cells promoted the growth of experimental mammary carcinomas in vivo. Analysis of the signaling mechanisms involved revealed that VE-cadherin expression influences the levels of Smad2 phosphorylation and expression of target genes of transforming growth factor-β (TGF-β), a major mediator of advanced tumor progression and malignant tumor cell proliferation. VE-cadherin might thus promote tumor progression not only by contributing to tumor angiogenesis but also by enhancing tumor cell proliferation via the TGF-β signaling pathway. This article provides evidence for a novel function of VE-cadherin in tumor progression and reveals a previously unknown molecular link between VE-cadherin expression and TGF-β signaling. Our findings may have important implications for the clinical application of anti–VE-cadherin strategies. [Cancer Res 2008;68(5):1388–97]