Pericyte coverage decreases invasion of tumour cells into blood vessels in prostate cancer xenografts

Androgen-independent prostate cancer is an aggressive disease with high angiogenic and metastatic potential. Increased microvessel density and altered invasion properties have previously been described in LNCaP-19, an androgen-independent subline to LNCaP. To characterize the differences in angiogenesis and invasion, the vessels of these tumour xenografts were investigated with immunohistochemistry, and the influence of tumour cells on endothelial cell migration, proliferation and tube formation was studied in vitro. The blood vessels of LNCaP were found to be stabilized by pericytes more frequently than vessels in LNCaP-19. Further, tumour cell invasion was decreased in pericyte-covered blood vessels in both the tumour types. LNCaP-19 displayed an increased potential to induce endothelial cell migration in vitro. In conclusion, pericyte coverage seems to be important for the invasion of tumour cells into blood vessels. Further, LNCaP-19 has lower pericyte coverage and an increased potential to induce endothelial cell migration, which reflects its high microvessel density.