MODULATION OF UROKINASE-TYPE PLASMINOGEN-ACTIVATOR GENE-EXPRESSION BYINFLAMMATORY CYTOKINES IN HUMAN PRE-B LYMPHOMA CELL-LINE RC-K8

We examined the effects of inflammatory cytokines, such as interleukin -1 alpha (IL-1 alpha), interleukin-1 beta (IL-1 beta), interleukin-6 ( IL-6), tumor necrosis factor-alpha (TNF alpha), transforming growth fa ctor-beta (TGF beta) and lipopolysaccharide (LPS), on the urokinase-ty pe plasminogen activator (uPA) gene expression in RC-K8 human pre-B ly mphoma cells. Recombinant IL-1 alpha, recombinant IL-1 beta and LPS bu t not recombinant IL-6, recombinant TNF alpha and TGF beta dose-depend ently increased uPA accumulation in the conditioned medium. Northern b lot analysis revealed that uPA mRNA levels rapidly increased with a pe ak induction at 2 h after stimulation with IL-1 alpha and IL-1 beta, b ut uPA mRNA increase by LPS began at 9 h after stimulation and the inc rease was maintained until the experiment ended at 24 h. These respons es were independent of de novo synthesis, rather amplified in the pres ence of a protein synthesis inhibitor. The effects by IL-1 alpha and I L-1 beta were prevented by addition of anti-IL-1 alpha and anti-IL-1 b eta neutralizing antibodies, respectively. In contrast, both antibodie s did not prevent LPS-induced uPA gene expression. Therefore, it is un likely that the effect by LPS is through induction of IL-1. Both IL-1 alpha and IL-1 beta rapidly activated uPA gene transcription, but not increased stability of uPA mRNA. These results suggest that both IL-1 alpha and IL-1 beta cause a rapid activation of uPA gene transcription in which de novo protein synthesis is not required and that LPS induc es uPA gene expression independently of the IL-1 pathway. These modula tions of uPA production by inflammatory mediators may be implicated in tumor growth and metastasis.