To clarify the biological and pathological features of choriocarcinoma, we evaluated the in vitro production of cytokines by a choriocarcinoma cell line, BeWo. We measured the concentration of interleukin (IL)-6 and IL-8 in the culture media of BeWo cells after stimulation with various modulatory agents of cytokine expression by enzyme-linked immunosorbent assays. Northern blot analysis was used to examine the expression of IL-6 and IL-8 mRNA in these cells. A weak expression of IL-6 and IL-8 was detected in unstimulated BeWo cells by both methods. IL-6 transcription and secretion were dose-dependently enhanced by stimulation with IL-1beta, tumour necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta1 and 12-O-tetradecanoyl phorbol-13-acetate (TPA). Forskolin, lipopolysaccharide and interferon-gamma had no effect on these cytokines production. The TNF-alpha-induced secretion of IL-6 was inhibited by dexamethasone. The TPA-induced production of IL-6 was inhibited by 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine and sphyngosine, suggesting the involvement of a protein kinase C-dependent pathway. Levels of IL-8 mRNA and protein were also dose-dependently increased by stimulation with IL-1beta, TNF-alpha and TPA. In contrast to IL-6, the expression of IL-8 was not affected by TGF-beta1. It is suggested that, in addition to the production of steroidal and non-steroidal hormones, these cytokines may serve as part of a cytokine network that modulates the proliferation and angiogenesis of choriocarcinomas.
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