Bcl-2 mediated modulation of vascularization in prostate cancer xenografts

We previously demonstrated that Bcl-2 overexpression enhances the radiation resistance of PC-3 human prostate cancer cells and xenografts by inhibiting apoptosis, increasing proliferation, and promoting angiogenesis. To further elucidate the relationship between Bcl-2 expression and the angiogenic potential of PC-3-Bcl-2 cells, tumorigenicity, angiogenesis, and lymphangiogenesis were evaluated and compared in a Bcl-2 overexpressing clone in vitro and in vivo.

Human prostate cancer cells over expressing Bcl-2 were studied in vitro and in vivo to determine the angiogenic and lymphangiogenic properties of these cells.

Increased Bcl-2 expression enhanced the tumorigenicity of prostate cancer xenografts. It also enhanced the expression and secretion of key angiogenic and lymphangiogenic factors that stimulated the synthesis of CD31-positive blood vessels and LYVE-1 positive lymphatics. Specifically, the increased angiogenic and lymphangiogenic potential correlated with increased serum levels of basic fibroblast growth factor (bFGF), interleukin 8 (CXCL8), and matrix metalloproteinase (MMP 9). In vitro analysis demonstrated that Bcl-2 expressing tumor cells secreted bFGF and vascular endothelial growth factor (VEGF) into culture supernatants. Microarray analysis of Bcl-2 expressing PC-3 cells demonstrated increased transcription of genes involved in metabolism, such as interleukins, growth factors, tumor necrosis factors (TNF) family members, and peptidases.

Together, these results demonstrate that Bcl-2 can regulate tumoral angiogenesis and lymphangiogenesis and suggest that therapy targeted at Bcl-2 expression, angiogenesis, and lymphangiogenesis may synergistically modulate tumor growth and confirm that Bcl-2 is a pivotal target for cancer therapy.