Wong L H, Krauer K G, Hatzinisiriou I, Estcourt M J, Hersey P, Tam N D, Edmondson S, Devenish R J, Ralph S J
Department of Biochemistry and Molecular Biology, Monash University, Wellington Road, Clayton, Victoria 3168, Australia.
J Biol Chem. 1997 Nov 7;272(45):28779-85. doi: 10.1074/jbc.272.45.28779.
The mechanism of IFN resistance was examined in three long-term cell lines, SK-MEL-28, SK-MEL-3, and MM96, exhibiting significant variation in responsiveness to the antiproliferative and antiviral effects of type I IFNs. The JAK-STAT components involved in IFN signal transduction were analyzed in detail. After exposure to IFN, activation of the IFN type I receptor-linked tyrosine kinases, JAK-1 and TYK-2, was detected at similar levels in both IFN-sensitive and IFN-resistant cell types, indicating that IFN resistance did not result from a deficiency in signaling at the level of receptor-associated kinase activation. However, analysis of ISGF3 transcription factor components, STAT1, STAT2, and p48-ISGF3gamma, revealed that their expression and activation correlated with cellular IFN responsiveness. The analysis was extended to also include IFN-sensitive primary melanocytes, three additional IFN-resistant melanoma cell lines, and seven cell cultures recently established from melanoma patient biopsies. It was consistently observed that the most marked difference in ISGF3 was a lack of STAT1 in the resistant versus the sensitive cells. Transfection of the IFN-resistant MM96 cell line to express increased levels of STAT1 protein partially restored IFN responsiveness in an antiviral assay. We conclude that a defect in the level of STAT1 and possibly all three ISGF3 components in IFN-resistant human melanoma cells may be a general phenomenon responsible for reduced cellular responsiveness of melanomas to IFNs.
在三种长期细胞系SK-MEL-28、SK-MEL-3和MM96中研究了IFN抗性机制，这些细胞系对I型IFN的抗增殖和抗病毒作用的反应性存在显著差异。详细分析了参与IFN信号转导的JAK-STAT组分。在暴露于IFN后，在IFN敏感和IFN抗性细胞类型中均检测到I型IFN受体相关酪氨酸激酶JAK-1和TYK-2的相似水平的激活，表明IFN抗性并非源于受体相关激酶激活水平的信号传导缺陷。然而，对ISGF3转录因子组分STAT1、STAT2和p48-ISGF3γ的分析表明，它们的表达和激活与细胞对IFN的反应性相关。分析范围还扩展到包括IFN敏感的原代黑素细胞、另外三种IFN抗性黑素瘤细胞系以及最近从黑素瘤患者活检组织建立的七种细胞培养物。一致观察到，ISGF3最显著的差异是抗性细胞与敏感细胞相比缺乏STAT1。在抗病毒试验中，转染IFN抗性MM96细胞系以表达增加水平的STAT1蛋白可部分恢复IFN反应性。我们得出结论，IFN抗性人黑素瘤细胞中STAT1水平以及可能所有三种ISGF3组分的缺陷可能是导致黑素瘤对IFN细胞反应性降低的普遍现象。
