The resistance to interferons (IFNs) limits their anticancer therapeutic efficacy. Here we studied the evolution of an IFN-resistant state in vitro using melanoma cell lines. We found that the cells became less sensitive to antiproliferative effect of IFN-gamma after prolonged cultivation enabling us to isolate sensitive and resistant subclones of the parental line. We investigated transcription of signal transducer and activator of transcription (STAT) 1-6 and suppressor of cytokine signalling (SOCS) 1-3 genes, and phosphorylation of STAT 1 protein. The resistant subline (termed WM 1158R) differed from the sensitive subline (WM 1158S) by a constitutive expression of SOCS 3, lack or weak SOCS 1-3 activation following IFN-gamma, and short duration of cytokine activatory signal. Similar correlations were observed in additional melanoma lines differing in IFN sensitivities. At the protein level, IFN-gamma induced strong and prolonged STAT 1 activation at serine 727 (S727) in WM 1158R while in WM 1158S cells phosphorylation of this amino acid was much less pronounced. On the other hand, phosphorylation of tyrosine 701 (Y701) was stimulated regardless of the sensitivity phenotype. In conclusion, constitutive expression of SOCS 3 is correlated with attenuation of its induction following IFN treatment. These results suggest that progression of melanoma cells from IFN sensitivity to IFN insensitivity associates with changes in SOCS expression.

• MeSH
• Drug Resistance, Neoplasm genetics   MeSH
• Gene Expression MeSH
• Phosphorylation MeSH
• Interferon-gamma pharmacology   therapeutic use   MeSH
• Humans MeSH
• Melanoma drug therapy   genetics   MeSH
• Cell Line, Tumor MeSH
• Skin Neoplasms drug therapy   genetics   MeSH
• Cell Proliferation drug effects   MeSH
• Suppressor of Cytokine Signaling 3 Protein MeSH
• Suppressor of Cytokine Signaling Proteins genetics   MeSH
• Gene Expression Regulation, Neoplastic * MeSH
• Gene Expression Profiling MeSH
• STAT1 Transcription Factor metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Interferon-gamma MeSH
• Suppressor of Cytokine Signaling 3 Protein MeSH
• Suppressor of Cytokine Signaling Proteins MeSH
• SOCS3 protein, human MeSH Browser
• STAT1 protein, human MeSH Browser
• STAT1 Transcription Factor MeSH