Galectins, a family of
glycan-
binding proteins, influence
tumor progression by modulating interactions between
tumor, endothelial, stromal, and immune cells. Despite considerable progress in identifying the roles of individual
galectins in
tumor biology, an integrated portrait of the
galectin network in different tumor microenvironments is still missing. We undertook this study to analyze the "
galectin signature" of the human
prostate cancer microenvironment with the overarching goal of selecting novel-molecular targets for prognostic and therapeutic purposes. In examining
androgen-responsive and
castration-resistant
prostate cancer cells and primary
tumors representing different stages of the disease, we found that
galectin-1 (Gal-1) was the most abundantly expressed
galectin in
prostate cancer tissue and was markedly upregulated during
disease progression. In contrast, all other
galectins were expressed at lower levels: Gal-3, -4, -9, and -12 were downregulated during disease evolution, whereas expression of Gal-8 was unchanged. Given the prominent regulation of
Gal-1 during
prostate cancer progression and its predominant localization at the
tumor-vascular interface, we analyzed the potential role of this endogenous
lectin in
prostate cancer angiogenesis. In human
prostate cancer tissue arrays,
Gal-1 expression correlated with the presence of blood vessels, particularly in advanced stages of the disease. Silencing
Gal-1 in
prostate cancer cells reduced
tumor vascularization without altering expression of other angiogenesis-related genes. Collectively, our findings identify a dynamically regulated "
galectin-specific signature" that accompanies disease evolution in
prostate cancer, and they highlight a major role for
Gal-1 as a tractable target for antiangiogenic
therapy in advanced stages of the disease.