Highly metastatic human prostate cancer growing within the prostate of athymic mice overexpresses vascular endothelial growth factor

Angiogenesis is essential for tumor progression and metastasis, It is media ted by the release of angiogenic factors by the tumor or host. We analyzed the expression of angiogenic factors by the prostate cancer cell line LNCaP and two derived variants, in vitro and in vivo, to determine whether metas tatic cell lines express higher levels of these factors, The production of three angiogenic factors, vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and interleukin 8 (IL-8), by LNCaP and its variants, LNCaP-LN3 (highly metastatic) and LNCaP-Pro5 (slightly metastati c), was measured by ELISA, VEGF, bFGF, and IL-8 mRNA expression was determi ned in vitro by Northern blot analysis. VEGF mRNA expression was determined in vivo by in situ hybridization, VEGF and flk-1 protein expression and mi crovessel density of LNCaP cell tumors were quantified by immunohistochemis try. In vitro, VEGF production by LNCaP-LN3 (3.15 +/- 0.04 pg/ml/10(3) cell s) was significantly higher than those of both LNCaP (2.38 +/- 0.34 pg/ml/1 0(3) cells) and LNCaP-Pro5 (1.67 +/- 0.37 pg/ml/10(3) cells; P = 0.049 and 0.001, respectively). None of the three cell lines produced detectable leve ls of bFGF or IL-8 in vitro. In vivo, LNCaP-LN3 tumors exhibited higher lev els of VEGF mRNA and protein (152.2 +/- 28.5 and 200.5 +/- 28.3) and of flk -1 protein (156.5 +/- 20.6) and had higher microvessel density (16.4 +/- 4. 2) than either LNCaP tumors (89 +/- 17.5, 173.3 +/- 23.0, 124.6 +/- 21.6, a nd 12.4 +/- 3.5, respectively) or LNCaP-Pro5 tumors (63 +/- 14.7, 141.2 +/- 38.1, 126.1 +/- 20, and 5.8 +/- 2.2, respectively). In conclusion, metasta tic human prostate cancer cells exhibited enhanced VEGF production and tumo r vascularity compared with prostate cancer cells of lower metastatic poten tial, Thus, VEGF may play an important role in prostate cancer metastasis.