Interferon-resistant human melanoma cells are deficient in ISGF3 components, STAT1, STAT2, and p48-ISGF3gamma.
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.
Wong
L H
LH
Department of Biochemistry and Molecular Biology, Monash University, Wellington Road, Clayton, Victoria 3168, Australia.
Krauer
K G
KG
Hatzinisiriou
I
I
Estcourt
M J
MJ
Hersey
P
P
Tam
N D
ND
Edmondson
S
S
Devenish
R J
RJ
Ralph
S J
SJ
D000970:Antineoplastic Agents / Q000627:therapeutic use*; D016207:Cytokines / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000032:analysis* / Q000235:genetics; D019008:Drug Resistance, Neoplasm; D006801:Humans; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D016898:Interferon-alpha / Q000494:pharmacology; D007372:Interferons / Q000627:therapeutic use*; D053613:Janus Kinase 1; D008545:Melanoma / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D050794:STAT1 Transcription Factor; D050795:STAT2 Transcription Factor; D015398:Signal Transduction; D053634:TYK2 Kinase; D015534:Trans-Activators / Q000032:analysis* / Q000235:genetics; D014157:Transcription Factors / Q000032:analysis* / Q000235:genetics; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism; D014452:Ubiquitins / Q000031:analogs & derivatives*
D000970:Antineoplastic Agents; D016207:Cytokines; D004268:DNA-Binding Proteins; C494227:IRF9 protein, human; D050832:Interferon-Stimulated Gene Factor 3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; D016898:Interferon-alpha; D011506:Proteins; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D050795:STAT2 Transcription Factor; C494084:STAT2 protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D014452:Ubiquitins; D014443:Tyrosine; C074034:ISG15 protein, human; D007372:Interferons; D011505:Protein-Tyrosine Kinases; C507904:JAK1 protein, human; D053613:Janus Kinase 1; D053634:TYK2 Kinase; C070139:TYK2 protein, human