Expression of the transcription factor STAT-1 alpha in insulinoma cells protects against cytotoxic effects of multiple cytokines.
Destruction of pancreatic islet beta-cells in type 1 diabetes appears to result from direct contact with infiltrating T-cells and macrophages and exposure to inflammatory cytokines such as interferon (IFN)-gamma, interleukin (IL)-1 beta, and tumor necrosis factor TNF-alpha that such cells produce. We recently reported on a method for selection of insulinoma cells that are resistant to the cytotoxic effects of inflammatory cytokines (INS-1(res)), involving their growth in progressively increasing concentrations of IL-1 beta plus IFN-gamma, and selection of surviving cells. In the current study, we have investigated the molecular mechanism of cytokine resistance in INS-1(res) cells. By focusing on the known components of the IFN-gamma receptor signaling pathway, we have discovered that expression levels of signal transducer and activator of transcription (STAT)-1 alpha are closely correlated with the cytokine-resistant and -sensitive phenotypes. That STAT-1 alpha is directly involved in development of cytokine resistance is demonstrated by an increase of viability from 10 +/- 2% in control cells to 50 +/- 6% in cells with adenovirus-mediated overexpression of STAT-1 alpha (p < 0.001) after culture of both cell groups in the presence of 100 units/ml IFN-gamma plus 10 ng/ml IL-1 beta for 48 h. The resistance to IL-1 beta plus IFN-gamma in STAT-1 alpha-expressing cells is due in part to interference with IL-1 beta-mediated stimulation of inducible nitric-oxide synthase expression and nitric oxide production. Furthermore, overexpression of STAT-1 alpha does not impair robust glucose-stimulated insulin secretion in the INS-1-derived cell line 832/13. We conclude that expression of STAT-1 alpha may be a means of protecting insulin-producing cell lines from cytokine damage, which, in conjunction with appropriate cell-impermeant macroencapsulation devices, may allow such cells to be used for insulin replacement in type 1 diabetes.
Chen
G
G
Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75235, USA.
Hohmeier
H E
HE
Newgard
C B
CB
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D016207:Cytokines / Q000037:antagonists & inhibitors* / Q000494:pharmacology / Q000633:toxicity*; D019008:Drug Resistance, Neoplasm; D005786:Gene Expression Regulation / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology; D006801:Humans; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007340:Insulinoma / Q000378:metabolism*; D050832:Interferon-Stimulated Gene Factor 3; D007371:Interferon-gamma / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D010766:Phosphorylation; D051381:Rats; D017471:Receptors, Interferon / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D014407:Tumor Cells, Cultured
D016207:Cytokines; D007328:Insulin; D050832:Interferon-Stimulated Gene Factor 3; D007375:Interleukin-1; D017471:Receptors, Interferon; D014157:Transcription Factors; C079868:gamma interferon activation factor; D009569:Nitric Oxide; D007371:Interferon-gamma; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D005947:Glucose