Human prostate tumor angiogenesis in nude mice: Metalloprotease and plasminogen activator activities during tumor growth and neovascularization of subcutaneously injected matrigel impregnated with human prostate tumor cells

Abstract

Background: A critical aspect for growth of solid tumors is the development of a blood supply. Our objective was to establish a model for the study of angiogenesis of human prostate tumors by examining the growth of microvessels into Matrigel containing human prostate tumor cells implanted subcutaneously in nude mice.Methods: Human prostate tumor cell lines PC-3 and LNCaP were injected in Matrigel under the abdominal skin of nude mice and were harvested at 4, 8, and 14 days post-injection. The growth of tumor cells and blood vessels was examined histologically and by immunohistochemical localization of von Willibrand Factor VIII (vWF). Since plasminogen activators and matrix metalloproteases are associated with angiogenesis, the activities and molecular forms of these proteases were determined in Matrigel control and Matrigel-tumor cell subcutaneous implants.Results: Blood vessel formation in the Matrigel implants containing LNCaP and PC-3 cells was demonstrable at 8 days post-injection. However, the pattern of blood vessel formation by the two tumor cell lines was different; PC-3 tumors showed a more invasive phenotype and smaller diameter blood vessels, whereas LNCaP tumors grew as large cellular spheroids surrounded by large, dilated blood vessels. Many blood vessels of PC-3 tumors expressed vWF by day 14 of growth, whereas most blood vessels in LNCaP tumors were immunohistochemically negative for this antigen. Mouse skin blood vessels in the same PC-3 and LNCaP tumor histological sections were positive for vWF.Matrigel contained both plasminogen activator and metalloprotease activities. The plasminogen activator activity in Matrigel control implants was totally inhibited by 4 days post-injection, indicating the presence of an inhibitor provided by the host mouse. LNCaP tumor cells injected did not have appreciable plasminogen activator activity, nor did LNCaP tumors develop plasminogen activator activity with tumor growth postinjection. PC-3 cells did have plasminogen activator activities, which were partially negated after subcutaneous injection (4 days), but then increased again by 8 days post-injection. This increase in plasminogen activator activity was due to urokinase (about 54 kDa) produced by the tumor and not by the mouse host (mouse urine urokinase about 44 kDa).

Differential expression of angiopoietin‐2 and vascular endothelial growth factor in androgen‐independent prostate cancer models

“…[22] reported no correlation between Ang‐2 and MVD in AI prostate cancer metastases. In the present study, Ang‐2 and VEGF expression seems to decrease during transition into androgen independence with dedifferentiation of the tumours, which could be indicated by the low PSA secretion in the LNCaP‐19 [8] and PC‐3 [23] compared with LNCaP. There are other studies reporting a decrease of VEGF in different AI prostate cancer cell lines, such as DU145, TSU‐Prl‐1, PC‐3 [24] and in poorly differentiated human cancer specimens [25], which supports the present data.…”

Increased Aggressiveness of Human Prostate PC‐3 Tumor Cells Expressing Cell Surface Localized Membrane Type‐1 Matrix Metalloproteinase (MT1‐MMP)

“…Mice were monitored weekly for tumor growth, and tumors were measured in 2 dimensions with calipers. Tumor volume was calculated as described previously (Wilson and Sinha, 1997). Tumors were removed at necropsy when they reached 1 cm 3 in size, or at the end of the experiment.…”

Vasculogenic Mimicry and Tumor Angiogenesis

“…Lauk et al 120 noted that in xenografts of human tumors, the cellular distribution and differentiation characteristics are retained, but the vascular density of the transplant is host specific. Wilson et al 121 cautioned that the organization of the microcirculation between different cell lines of prostate cancer varied, implying that each tumor may exert "unique influences" on the pattern of microvessel development.…”