Mediation of enhanced transcription of the IL-10 gene in T cells, upon contact with human glioma cells, by Fas signaling through a protein kinase A-independent pathway.
Elevated expression of IL-10 has been frequently observed in tumor tissues and tumor-infiltrating cells. We show herein that transcription of the IL-10 gene in primary peripheral T cells and T cell lines is up-regulated upon contact with glioma cells without an induction of apoptosis in those T cells. Glioma-associated IL-10 induction was suppressed by interrupting the engagement of Fas and its ligand (Fas-L) with the antagonistic Ab, ZB4, by reducing Fas-L expression of glioma cells using the Fas-L-specific ribozyme, or by preventing cell-to-cell contact in a Transwell culture setting. Cross-linking of Fas with the agonistic Ab, CH-11, triggered apoptosis and enhanced the expression of IL-10 in Jurkat cells at the transcriptional and translational levels. Inhibiting caspase activities by caspase inhibitors, Z-VAD (Z-Val-Ala-Asp(Ome)-fluoromethylketone) and Z-IETD (Z-Ile-Glu(Ome)-Thr(Ome)-Asp(Ome)-fluoromethylketone), abolished this IL-10 induction in Jurkat cells. Intracellular staining detected IL-10 proteins in Fas-cross-linked Jurkat cells and in PHA-activated T cells. However, few IL-10 proteins were detectable in Jurkat cells cocultured with glioma cells, indicating a requirement of other factors for IL-10 production. Direct activation of protein kinase A (PKA) by forskolin elevated the transcription of IL-10 in Jurkat cells. However, KT5720, a selective PKA inhibitor, reduced neither anti-Fas-triggered nor glioma-associated IL-10 expression. Phosphorylation of cAMP response element binding protein and activating transcription factor-1 in Jurkat cells was not affected by coculturing with glioma cells or by anti-Fas treatment, further suggesting a PKA-independent pathway. In summary, our results demonstrate nonlethal cross-talk between tumor and immune cells leading to IL-10 dysregulation in T cells, which might contribute to Fas-L(+) tumor-associated immunosuppression.
Yang
Bei-Chang
BC
Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, Taiwan, Republic of China. y1357@mail.ncku.edu.tw
Lin
Heng-Kai
HK
Hor
Wei-Shio
WS
Hwang
Jun-Yen
JY
Lin
Yu-Ping
YP
Liu
Ming-Yie
MY
Wang
Ying-Jan
YJ
D019138:Antibodies, Blocking / Q000494:pharmacology; D017209:Apoptosis / Q000235:genetics / Q000276:immunology; D020169:Caspases / Q000378:metabolism / Q000502:physiology; D002450:Cell Communication / Q000235:genetics / Q000276:immunology*; D045744:Cell Line, Tumor; D018920:Coculture Techniques; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology*; D004789:Enzyme Activation / Q000276:immunology; D053222:Fas Ligand Protein; D015972:Gene Expression Regulation, Neoplastic / Q000276:immunology; D005910:Glioma / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D006801:Humans; D016753:Interleukin-10 / Q000096:biosynthesis / Q000097:blood / Q000235:genetics*; D007424:Intracellular Fluid / Q000276:immunology / Q000378:metabolism; D019169:Jurkat Cells; D008024:Ligands; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism; D014158:Transcription, Genetic / Q000276:immunology*; D015854:Up-Regulation / Q000235:genetics / Q000276:immunology*; D019014:fas Receptor / Q000276:immunology / Q000378:metabolism / Q000502:physiology*
D019138:Antibodies, Blocking; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008024:Ligands; D008562:Membrane Glycoproteins; D019014:fas Receptor; D016753:Interleukin-10; D017868:Cyclic AMP-Dependent Protein Kinases; D020169:Caspases