Previously we have shown that the
matrix metalloproteinase matrilysin (MMP-7) is overexpressed in human
prostate cancers compared with normal epithelium. However, the mechanism for this overexpression is not understood. Human prostate fibroblasts have been shown to express certain
fibroblast growth factors (FGFs), including
FGF-1. Evidence from our laboratory and others has indicated that FGFs can regulate the expression of certain
matrix metalloproteinases, including
matrilysin. The goal of this study was to determine whether pharmacological inhibition of FGFR signaling would alter LNCaP
tumor growth as well as expression of
promatrilysin when LNCaP cells were co-injected subcutaneously with human prostate fibroblasts into athymic nude mice. For these inhibitor studies, AG1-X2 beads were coated with the pharmacological FGFR inhibitor
SU5402 and were co-injected along with LNCaP and human prostate fibroblast cells (PF). Mice injected with LNCaP/PF and LNCaP/PF/beads alone demonstrated significant
tumor growth, whereas mice injected with LNCaP/PF/
SU5402-coated beads showed a significant decrease in
tumor volume and weight. Immunohistochemical analysis showed that significant
promatrilysin expression in
tumors was inhibited by the FGFR inhibitor
SU5402. Serum
prostate-specific antigen (PSA) and
promatrilysin levels were measured by
enzyme-linked
immunosorbent assay. The mice injected with LNCaP/PF and LNCaP/PF/beads expressed
promatrilysin and serum PSA levels that were inhibited by co-injecting with
SU5402. Therefore, pharmacological inhibition of
FGF receptor signaling results in a decrease in the growth of LNCaP
tumors generated subcutaneously by co-injecting LNCaP cells and human prostate fibroblasts. The inhibition in
tumor growth was correlated with a decrease in
tumor promatrilysin expression and a decrease in serum
promatrilysin and PSA.