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Melanoma cells exhibit variable signal transducer and activator of transcription 1 phosphorylation and a reduced response to IFN-alpha compared with immune effector cells.
- Source :
-
Clinical cancer research : an official journal of the American Association for Cancer Research [Clin Cancer Res] 2007 Sep 01; Vol. 13 (17), pp. 5010-9. - Publication Year :
- 2007
-
Abstract
- Purpose: IFN-alpha is administered to melanoma patients and its endogenous production is essential for immune-mediated tumor recognition. We hypothesized that a reduced capacity for signal transducer and activator of transcription (STAT) 1 activation allows melanoma cells to evade the direct actions of IFN-alpha.<br />Experimental Design: Tyr(701)-phosphorylated STAT1 (P-STAT1) was measured by flow cytometry in IFN-alpha-stimulated human melanoma cell lines, melanoma cells derived from patient tumors, and peripheral blood mononuclear cells (PBMC). Expression of other Janus-activated kinase (Jak)-STAT intermediates (STAT1, STAT2, Jak1, tyrosine kinase 2, IFN-alpha receptor, STAT3, and STAT5) was evaluated by flow cytometry, immunoblot, or immunohistochemistry.<br />Results: Significant variability in P-STAT1 was observed in human melanoma cell lines following IFN-alpha treatment (P < 0.05) and IFN-alpha-induced P-STAT1 correlated with the antiproliferative effects of IFN-alpha (P = 0.042). Reduced formation of P-STAT1 was not explained by loss of Jak-STAT proteins or enhanced STAT5 signaling as reported previously. Basal levels of P-STAT3 were inversely correlated with IFN-alpha-induced P-STAT1 in cell lines (P = 0.013). IFN-alpha-induced formation of P-STAT1 was also variable in melanoma cells derived from patient tumors; however, no relationship between P-STAT3 and IFN-alpha-induced P-STAT1 was evident. Because IFN-alpha acts on both tumor and immune cells, we examined the ability of IFN-alpha to induce P-STAT1 in patient-derived melanoma cells and PBMCs. IFN-alpha induced significantly lower levels of P-STAT1 in melanoma cells compared with matched PBMCs (P = 0.046). Melanoma cells and human melanocytes required 10-fold higher IFN-alpha doses to exert P-STAT1 levels comparable with PBMCs.<br />Conclusions: Melanoma cells are variable in their IFN-alpha responsiveness, and cells of the melanocytic lineage exhibit a lower capacity for IFN-alpha-induced Jak-STAT signaling compared with immune cells.
- Subjects :
- Animals
Humans
Janus Kinase 1 metabolism
Melanoma immunology
Melanoma pathology
Mice
Phosphorylation
STAT2 Transcription Factor analysis
STAT3 Transcription Factor metabolism
STAT5 Transcription Factor metabolism
Interferon-alpha pharmacology
Melanoma metabolism
STAT1 Transcription Factor metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1078-0432
- Volume :
- 13
- Issue :
- 17
- Database :
- MEDLINE
- Journal :
- Clinical cancer research : an official journal of the American Association for Cancer Research
- Publication Type :
- Academic Journal
- Accession number :
- 17785551
- Full Text :
- https://doi.org/10.1158/1078-0432.CCR-06-3092