PMID: 9164976Jun 1, 1997Paper

Enhancement of gp130-mediated tyrosine phosphorylation of STAT3 and its DNA-binding activity in dexamethasone-treated AIDS-associated Kaposi's sarcoma cells: selective synergy between dexamethasone and gp130-related growth factors in Kaposi's sarcoma cell proliferation

The Journal of Immunology : Official Journal of the American Association of Immunologists
K Murakami-MoriS Nakamura

Abstract

The soluble IL-6R (slL-6R alpha)/IL-6 complex and oncostatin M (OM), which exert biologic activities through the signal-transducing protein gp130, are potent growth factors for AIDS-associated Kaposi's sarcoma (KS) cells. Clinical observations indicate that glucocorticoid therapy is a possible risk factor in KS; however, little is known of specific interactions in KS cells between glucocorticoid and gp130-related growth factors. We obtained evidence that dexamethasone (Dex), in a synergistic manner, enhances gp130-mediated growth of KS cells. Anti-gp130 Abs or the glucocorticoid antagonist RU-486 abolished this synergistic effect. In addition, Dex had additive but not synergistic effects on stimulation of KS cell growth with IL-1beta or TNF-alpha, the signals of which are not mediated through gp130. Immunoblot analysis revealed sIL-6R alpha/IL-6- or OM-induced tyrosine phosphorylation of a similar set of proteins in KS cells, and which was augmented significantly in Dex-treated KS cells. Stimulation of KS cells with sIL-6R alpha/IL-6 or OM induced rapid tyrosine phosphorylation of the transcription factor STAT3, and Dex significantly enhanced the accumulation of tyrosine-phosphorylated STAT3. Electrophoretic mobility shift assa...Continue Reading

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