| Research Abstract |
The mechanisms of IL-latiproliferative effect and the acquired resistance to IL-1 effect were studied using human melanoma cells A375. As type I IL-1 receptor (IL-1R) transduces IL-1 signal, the regulatory mechanisms of IL-1R expression in vitro and in vivo were also studied.
1. The mechanism of IL-1 antiproliferative effect
IL-1R cDNA was transfected into A375-5 which is resistant to IL-1 because it expresses very low number of IL-1R.We obtained the transfectant which became sensitive to IL-1. Using this clone we studied the IL-1 signaling. IL-1 downregulated ODC activity. Although ODC mRNA level was not changed, the amount of protein of ODC decreased. The mRNA of antizyme (AZ), a proteinous factor which inactivates ODC by binding to ODC and causes degradation of ODC,was upregulated by IL-1. Furthermore, antisense of AZ inhibited IL-1 effects. Terefore, AZ induced by IL-1 appeared to be important in the IL-1 signaling.
2. The mechanism of acquired resistance to IL-1
Using the cells which acquired resistance to IL-1 antiproliferative effect after long period of culture, we studied the mechanism. Expression vectors of IL-1alpha sense and IL-1alpha antisense were transfected into IL-1 sensitive and resistant cells, respectively. However, the sensitivity of the transfectants to IL-1 was not changed. Therefore, expression of IL-1alpha appeared not to be sufficient to the resistance.
3. Regulation of IL-1R expression
Using human fibroblast cell line TIG-1, we studied the regulatory mechanism of type I IL-1R wxpression. Tyrosine kinase appeared to play an important role in constitutive expression of IL-1R.Whtn mice were injected with LPS,a marked increase of IL-1R mRNA was induced in the liver. The upregulation apperaed to be induced by the endogenously produced IL-1 and IL-6.
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