TNF-alpha induction of GM2 expression on renal cell carcinomas promotes T cell dysfunction.
Previous studies from our laboratory demonstrated the role of tumor-derived gangliosides as important mediators of T cell apoptosis, and hence, as one mechanism by which tumors evade immune destruction. In this study, we report that TNF-alpha secreted by infiltrating inflammatory cells and/or genetically modified tumors augments tumor-associated GM2 levels, which leads to T cell death and immune dysfunction. The conversion of weakly apoptogenic renal cell carcinoma (RCC) clones to lines that can induce T cell death requires 3-5 days of TNF-alpha pretreatment, a time frame paralleling that needed for TNF-alpha to stimulate GM2 accumulation by SK-RC-45, SK-RC-54, and SK-RC-13. RCC tumor cell lines permanently transfected with the TNF-alpha transgene are similarly toxic for T lymphocytes, which correlates with their constitutively elevated levels of GM2. TNF-alpha increases GM2 ganglioside expression by enhancing the mRNA levels encoding its synthetic enzyme, GM2 synthase, as demonstrated by both RT-PCR and Southern analysis. The contribution of GM2 gangliosides to tumor-induced T cell death was supported by the finding that anti-GM2 Abs significantly blocked T cell apoptosis mediated by TNF-alpha-treated tumor cells, and by the observation that small interfering RNA directed against TNF-alpha abrogated GM2 synthase expression by TNF-transfected SK-RC-45, diminished its GM2 accumulation, and inhibited its apoptogenicity for T lymphocytes. Our results indicate that TNF-alpha signaling promotes RCC-induced killing of T cells by stimulating the acquisition of a distinct ganglioside assembly in RCC tumor cells.
Raval
Gira
G
Department of Immunology, Lerner Research Institute, Experimental Therapeutics, Taussig Cancer Center, Cleveland Clinic Foundation, OH 44195, USA.
Biswas
Soumika
S
Rayman
Patricia
P
Biswas
Kaushik
K
Sa
Gaurisankar
G
Ghosh
Sankar
S
Thornton
Mark
M
Hilston
Cynthia
C
Das
Tanya
T
Bukowski
Ronald
R
Finke
James
J
Tannenbaum
Charles S
CS
D000276:Adjuvants, Immunologic / Q000502:physiology; D019138:Antibodies, Blocking / Q000494:pharmacology; D017209:Apoptosis / Q000276:immunology; D002292:Carcinoma, Renal Cell / Q000276:immunology* / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D005678:G(M2) Ganglioside / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology; D015972:Gene Expression Regulation, Neoplastic / Q000276:immunology*; D006027:Glycosides / Q000096:biosynthesis / Q000502:physiology; D006801:Humans; D007680:Kidney Neoplasms / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D016192:Resting Phase, Cell Cycle / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology* / Q000378:metabolism / Q000473:pathology*; D014162:Transfection; D019139:Tumor Escape / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000276:immunology / Q000502:physiology*; D015854:Up-Regulation / Q000276:immunology
D000276:Adjuvants, Immunologic; D019138:Antibodies, Blocking; D006027:Glycosides; D014409:Tumor Necrosis Factor-alpha; D005678:G(M2) Ganglioside