Effect of prostaglandin E₂ on urokinase‐type plasminogen activator production by human lung fibroblasts

Abstract

Human lung fibroblasts are components of stromal tissue and produce various proteins as occasion demands, such as extracellular matrix (ECM) components and proteases. Pulmonary tumour cells produce high levels of prostaglandin E₂ (PGE₂), which regulates tumour growth and metastasis. Urokinase‐type plasminogen activator (uPA) is essential in the degradation of peritumour ECM. Furthermore, uPA is an important protease believed responsible for several tumour characteristics through its activation of certain proteases and growth factors. We hypothesized that the PGE₂ overexpression from tumour cells would have some effect on uPA expression in lung fibroblasts. In this study, the influence of PGE₂ on uPA expression in human lung fibroblasts was investigated using two lines of such fibroblasts. Although the cell surface uPA level was comparable to that of PGE₂ untreated cells, the expression of uPA mRNA and production was increased by the addition of PGE₂ in both lines of fibroblasts. These fibroblasts expressed both the EP₂ and EP₄ PGE₂ receptor mRNAs. Pretreatment with EP₂ and/or EP₄ receptor antagonists reduced the intercellular and cell surface uPA expression of the human lung fibroblasts. These results indicated that there is a relationship between the PGE₂ system and uPA production in human lung fibroblasts operating through EP₂ and/or EP₄ receptor signalling. uPA induced by PGE₂ from stromal fibroblasts surrounding lung tumour thus appears to play an important role through these EP receptors. Inhibition of EPs in tumour tissue might be a useful strategy for anti‐metastasis therapy.

• AH23848
• AH6809
• arachidonic acid
• cell migration
• cell signalling
• ELISA
• peritumour ECM
• RT‐PCR analysis
• tumour growth
• Western blot analysis