Abstracts Biological Sciences

The regulation of matrilysin expression in prostate carcinoma cells by paracrine interactions with stromal cells

by Russell David Klein

Matrilysin is a matrix metalloprotease that degrades extracellular matrix and basement membrane components. Matrilysin expression is elevated in prostate cancers and is associated with increased histological grade and clinical stage of prostate cancer. We have proposed that the overexpression of matrilysin in prostate cancer cells could be due to stimulation by paracrine factors from stromal cells. Human prostate cancer cell lines were cultured with prostate-derived fibroblasts and fibroblast conditioned media (PFCM). PFCM induced matrilysin expression in three of six prostate cancer cell lines, including the cell line LNCaP. Biochemical characterization of the matrilysin inducing activity in PFCM identified fibroblast growth factors (FGFs) as candidates for this activity. Recombinant FGF-1, FGF-2, FGF-9 and FGF-10 induced matrilysin expression in LNCaP cells. The expression of these FGFs by prostate fibroblasts was verified using RT-PCR. Using a specific inhibitor of FGF receptor activation, we demonstrated that a significant portion of the matrilysin inducing activity of PFCM is dependent on activation of LNCaP cell FGF receptors. Matrilysin expression in normal prostate epithelial cells (PrEC) is not enhanced by treatment with FGFs or PFCM. Aberrant expression of FGFR-1 was observed in LNCaP cells, revealing a potential explanation for the ability of FGFs to induce matrilysin in LNCaP but not PrEC cells. Matrilysin expression is also elevated in inflamed ductile and acinar prostate epithelial cells associated with infiltrating macrophages. Therefore, the ability of monocyte secreted factors to induce matrilysin expression in prostate epithelial cells was determined. Treatment of LNCaP and PrEC cells with conditioned media from activated monocyte cultures induced matrilysin expression in these cells. The factor responsible for this induction was identified as interleukin-1β (IL-1β) using an anti-IL-1β neutralizing antibody. IL-1β induced transactivation of a reporter construct containing cis-elements from the human matrilysin promoter in LNCaP cells, indicating an effect of IL-1β on matrilysin gene transcription. An inhibitor of NF k B activity, pyrollidine dithiocarbamate (PDTC), blocked induction of matrilysin in LNCaP cells by IL-1β. This result implies a role for NFκB in the induction of matrilysin expression by IL-1β, an implication supported by evidence that IL-1β induces NFκB activity in LNCaP cells.