Vascular endothelial growth factor (
VEGF) is overexpressed during the transition from prostate intraepithelial
neoplasia (PIN) to invasive
carcinoma. We have mimicked such a process in vitro using the PIN-like C3(1)/Tag-derived Pr-111 cell line, which expresses low levels of
VEGF and exhibits very low tumorigenicity in vivo. Elevated expression of VEGF164 in Pr-111 cells led to a significant increase in tumorigenicity, invasiveness, proliferation rates and angiogenesis. Moreover, VEGF164 induced strong changes in cell morphology and cell transcriptome through an autocrine mechanism, with changes in TGF-beta1- and cytoskeleton-related pathways, among others. Further analysis of
VEGF-overexpressing Pr-111 cells or following exogenous addition of recombinant
VEGF shows acquisition of epithelial-mesenchymal transition (EMT) features, with an increased expression of mesenchymal markers, such as
N-cadherin, Snail1, Snail2 (Slug) and
vimentin, and a decrease in
E-cadherin. Administration of
VEGF led to changes in
TGF-beta1 signaling, including reduction of Smad7 (
TGF-beta inhibitory Smad), increase in TGF-betaR-II, and translocation of phospho-Smad3 to the nucleus. Our results suggest that increased expression of
VEGF in malignant cells during the transition from PIN to invasive
carcinoma leads to EMT through an autocrine loop, which would promote
tumor cell invasion and motility. Therapeutic blockade of
VEGF/TGF-beta1 in PIN lesions might impair not only
tumor angiogenesis, but also the early dissemination of malignant cells outside the epithelial layer.