| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
* Department of Immunology, Lerner Research Institute and
Experimental Therapeutics, Taussig Cancer Center, Cleveland Clinic Foundation, Cleveland, OH 44195; and
Molecular Medicine Division, Bose Institute, Kolkata, India
Tumors can promote their own progressive growth by inducing T cell apoptosis. Though previous studies suggested that tumor-mediated T cell killing is receptor dependent, we recently showed that tumor gangliosides also participate, a notion consistent with reports indicating that, in some cell types, gangliosides can activate the intrinsic apoptotic pathway by stimulating reactive oxygen species production, cytochrome c release, and caspase-9 activation. In this study, we used normal peripheral blood T cells, as well as caspase-8-, caspase-9-, and Fas-associated death domain protein-deficient Jurkat cells, to assess whether the death ligands and gangliosides overexpressed by the renal cell carcinoma (RCC) cell line SK-RC-45 can independently stimulate T cell apoptosis as a mechanism of immune escape. Anti-FasL Abs and the glycosylceramide synthase inhibitor 1-phenyl-2-hexadecanoylamino-3-pyrrolidino-1-propanol (PPPP) each partially inhibited the ability of SK-RC-45 to kill cocultured activated T cells; together, as purified molecules, RCC gangliosides and rFasL induced a more extensive mitochondrial permeability transition and greater levels of apoptosis than either agent alone, equivalent to that induced by the FasL- and ganglioside-expressing RCC line itself. rFasL-mediated apoptosis was completely inhibited in caspase-8- and Fas-associated death domain protein-negative Jurkat cells, though apoptosis induced by purified gangliosides remained intact, findings that correlate with the observed partial inhibition of SK-RC-45-induced apoptosis in the Jurkat lines with defective death receptor signaling. Western blot analysis performed on lysates made from wild-type and mutant Jurkat cells cocultured with SK-RC-45 revealed caspase activation patterns and other biochemical correlates which additionally supported the concept that tumor-associated gangliosides and FasL independently activate the caspase cascade in T cells through the intrinsic and extrinsic pathways, respectively.
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
1 This work was supported by National Institutes of Health Grants RO1-CA111917, CA056937, and CA116255.
2 T.D. and G.S. contributed equally to this work.
3 Current address: Department of Lymphoproliferative Disorders, Maria Sklodowska-Curie Cancer Center, Warsaw, ul. WK Roentgena 5 02-781, Poland.
4 Address correspondence and reprint requests to Dr. Charles S. Tannenbaum, Department of Immunology, Lerner Research Institute, Cleveland Clinic Foundation, Room NE4-308, 9500 Euclid Avenue, Cleveland, OH 44195. E-mail address: Tannenc{at}ccf.org
5 Abbreviations used in this paper: RCC, renal cell carcinoma; PPPP, 1-phenyl-2-hexadecanoylamino-3-pyrrolidino-1-propanol; FADD, Fas-associated death domain protein; MPT, mitochondrial permeability transition; NAT, tumor-adjacent normal tissue; NKE, normal human kidney epithelial; DAPI, 4',6'-diamidino-2-phenylindole; HPTLC; high performance thin layer chromatography.
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
