IFN-alpha-induced signal transduction, gene expression, and antitumor activity of immune effector cells are negatively regulated by suppressor of cytokine signaling proteins

Proteins belonging to the suppressors of cytokine signaling (SOCS) family have been shown to regulate cytokine signal transduction in various cell types but their role in modulating the response of immune cells to IFN-alpha has not been fully explored. We hypothesized that SOCS proteins would inhibi...

Full description

Saved in:

Bibliographic Details
Published in:	Journal of Immunology 2007-04, Vol.178 (8), p.4832-4845
Main Authors:	Zimmerer, Jason M, Lesinski, Gregory B, Kondadasula, Sri Vidya, Karpa, Volodymyr I, Lehman, Amy, Raychaudhury, Abhik, Becknell, Brian, Carson, 3rd, William E
Format:	Article
Language:	eng
Subjects:	Animals Antineoplastic Agents - pharmacology CD8-Positive T-Lymphocytes - immunology Cell Line, Tumor Gene Expression - drug effects Humans Interferon-alpha - pharmacology Jurkat Cells Mice Mice, Inbred C57BL RNA, Small Interfering - pharmacology Signal Transduction - drug effects Suppressor of Cytokine Signaling 1 Protein Suppressor of Cytokine Signaling 3 Protein Suppressor of Cytokine Signaling Proteins - genetics Suppressor of Cytokine Signaling Proteins - physiology
Online Access:	Get full text
Tags:	Add Tag No Tags, Be the first to tag this record!

Description
Summary:	Proteins belonging to the suppressors of cytokine signaling (SOCS) family have been shown to regulate cytokine signal transduction in various cell types but their role in modulating the response of immune cells to IFN-alpha has not been fully explored. We hypothesized that SOCS proteins would inhibit the antitumor activity of IFN-alpha-stimulated immune cells. Transcripts for SOCS1, SOCS2, SOCS3, and cytokine-inducible Src homology 2-containing protein were identified in total human PBMC (PBMCs, NK cells, and T cells) within 1-2 h of stimulation with IFN-alpha (10(3)-10(5) U/ml). Immunoblot analysis confirmed the expression of these factors at the protein level. Transcripts for SOCS proteins were rapidly but variably induced in PBMCs from patients with metastatic melanoma following the i.v. administration of IFN-alpha-2b (20 million units/m(2)). Overexpression of SOCS1 and SOCS3, but not SOCS2, in the Jurkat T cell line inhibited IFN-alpha-induced phosphorylated STAT1 and the transcription of IFN-stimulated genes. Conversely, small inhibitory RNA-mediated down-regulation of SOCS1 and SOCS3 in Jurkat cells and normal T cells enhanced the transcriptional response to IFN-alpha. Loss of SOCS1 or SOCS3 in murine immune effectors was associated with enhanced IFN-induced phosphorylated STAT1, transcription of IFN-stimulated genes, and antitumor activity. Of note, IFN-alpha treatment eliminated melanoma tumors in 70% of SOCS1-deficient mice, whereas IFN-treated SOCS-competent mice all died. The antitumor effects of IFN-alpha in tumor-bearing SOCS1-deficient mice were markedly inhibited following depletion of CD8(+) T cells. These results indicate that the antitumor response of immune effector cells to exogenous IFN-alpha is regulated by SOCS proteins.
ISSN:	0022-1767 1550-6606 1365-2567