Impaired STAT phosphorylation in T cells from melanoma patients in response to IL-2: association with clinical stage.
OBJECTIVE
To assess the extent of signal transducer and activator of transcription (STAT) activation in response to interleukin 2 (IL-2) in melanoma patients' T cells, along with clinical stage of tumor progression.


METHODS
T lymphocytes from peripheral blood of healthy donors and of American Joint Committee on Cancer stage I to IV melanoma patients, as well as from metastatic lymph nodes of patients, were evaluated for responsiveness to IL-2. CFSE assays and single-cell phospho-STAT-specific flow cytometry screening were used. Results. T cells from advanced melanoma patients, in comparison with healthy donors, showed reduced proliferation to IL-2 and IL-15, but not to anti-CD3 monoclonal antibody. Impaired response occurred in CCR7(+) and CCR7(-) T-cell subsets, but not in CD3(-) CD8(+) natural killer (NK) cells, and was not explained by induction of apoptosis, increased cytokine consumption, or altered IL-2R subunit expression in patients' T lymphocytes. By phospho-specific flow cytometry, defective STAT1 and STAT5 activation in response to IL-2 was found mainly in T lymphocytes from peripheral blood and/or tumor site of American Joint Committee on Cancer stage III and IV patients, compared with stage I and II patients and to donors, and in melanoma antigen-specific T cells isolated from metastatic lymph nodes. At tumor site, impaired STAT activation in T cells did not correlate with frequency of CD4(+) CD25(+) Foxp3(+) T cells. Serum from advanced melanoma patients inhibited IL-2-dependent STAT activation in donors' T cells and a neutralizing monoclonal antibody to transforming growth factor beta1 counteracted such inhibition.


CONCLUSIONS
These results provide evidence for development of impaired STAT signaling in response to IL-2, along with clinical evolution of the disease, in melanoma patients' T cells.
Mortarini
Roberta
R
Department of Experimental Oncology, Human Tumors Immunobiology Unit, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
Vegetti
Claudia
C
Molla
Alessandra
A
Arienti
Flavio
F
Ravagnani
Fernando
F
Maurichi
Andrea
A
Patuzzo
Roberto
R
Santinami
Mario
M
Anichini
Andrea
A
D017252:CD3 Complex / Q000276:immunology / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D006801:Humans; D019409:Interleukin-15 / Q000494:pharmacology; D007376:Interleukin-2 / Q000494:pharmacology*; D053616:Janus Kinase 3 / Q000276:immunology / Q000378:metabolism; D007694:Killer Cells, Natural / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D008545:Melanoma / Q000276:immunology* / Q000473:pathology; D009367:Neoplasm Staging; D010766:Phosphorylation / Q000187:drug effects; D018121:Receptors, Cytokine / Q000276:immunology / Q000378:metabolism; D050794:STAT1 Transcription Factor / Q000378:metabolism*; D050799:STAT5 Transcription Factor / Q000378:metabolism*; D012878:Skin Neoplasms / Q000276:immunology* / Q000473:pathology; D013601:T-Lymphocytes / Q000187:drug effects* / Q000378:metabolism
D017252:CD3 Complex; D019409:Interleukin-15; D007376:Interleukin-2; D018121:Receptors, Cytokine; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D050799:STAT5 Transcription Factor; C507933:JAK3 protein, human; D053616:Janus Kinase 3