http://192.168.1.40:8080/xmlui/handle/123456789/1430 2026-05-31T14:25:03Z http://192.168.1.40:8080/xmlui/handle/123456789/2364 The Bcl-2 transgene protects T cells from renal cell carcinoma-mediated apoptosis Molto, L.; Rayman, P.; Paszkiewicz-Kozik, E.; Thornton, M.; Reese, L.; Thomas, J. C.; Das, Tanya; Kudo, D.; Bukowski, R.; Finke, J.; Tannenbaum, C. Purpose: Tumors induce T-cell apoptosis as a mechanism. of inhibiting antitumor immunity. Using coculture experiments, it has been shown that tumor lines stimulate T-cell apoptosis by a pathway involving a mitochondrial permeability transition and cytochrome c release. Activated T cells express abundant levels of Bcl-2, an antiapoptotic molecule that would be expected to confer resistance to such tumor-mediated killing. We examined the mechanism by which Bcl-2 is dysregulated in T cells exposed to the renal tumor line SK-RC-45, and we determined whether overexpressing Bcl-2 protects T cells from tumor-mediated apoptosis. Experimental Design: Activated T lymphocytes and Jurkat cells transfected or not transfected with Bcl-2 were exposed to SK-RC-45 for 48-72 h. After coculture, lymphocytes were analyzed for Bcl-2 expression using Western analysis and for tumor-induced apoptosis by terminal deoxynucleotidyl transferase-mediated nick end labeling. The role of SK-RC-45-stimulated caspase activation in degrading T-cell Bcl-2 was assessed using a pan-caspase inhibitor, as well as a specific inhibitor of caspase-9. Results: The renal cell carcinoma cell line SK-RC-45 sensitizes peripheral blood activated T lymphocytes and Jurkat cells to apoptosis by a mechanism that involves degradation of the antiapoptotic protein Bcl-2. The SK-RC-45-induced modulation of lymphocyte Bcl-2 levels was largely caspase independent because pretreatment of T cells with p an-caspase inhibitor III or an inhibitor of caspase-9 had minimal or no effect on stabilizing the protein, although it did provide protection against apoptosis. Overexpression of Bcl-2 protected Jurkat cells from tumor-mediated killing. Conclusions: Bcl-2 inhibition is a mechanism by which tumors may render lymphocytes sensitive to other tumor-derived, proapoptotic stimuli. 2003-08-15T00:00:00Z http://192.168.1.40:8080/xmlui/handle/123456789/2269 Over-expressed IgG2 antibodies against O-acetylated sialoglycoconjugates incapable of proper effector functioning in childhood acute lymphoblastic leukemia Bandyopadhyay, S.; Bhattacharyya, A.; Mallick, A.; Sen, A. K.; Tripathi, G.; Das, Tanya; Sa, Gaurisankar; Bhattacharya, D. K.; Mandal, C. Earlier studies have demonstrated an over-expression of 9-O-acetylated sialoglycoconjugates (9-OAcSGs) on lymphoblasts, concomitant with high titers of anti-9-OAcSGs in childhood acute lymphoblastic leukemia (ALL). The present study was aimed to evaluate whether this high induction of anti-9-OAcSGs at disease presentation contributes toward immune surveillance. Accordingly, anti-9-OAcSGs were affinity purified from sera of ALL patients and normal individuals, and their specificity toward the glycotope having terminal 9-O-acetylated sialic acid-linked subterminal N-acetyl galactosamine (GalNAc) in alpha2-6 manner (9-OAcSAalpha2-6GalNAc) was established by hemagglutination assay, flow cytometry and confocal microscopy. Subclass distribution of anti-9-OAcSGs revealed a predominance of IgG2 in ALL. Analysis of glycosylation of anti-9-OAcSGs purified from sera of ALL patients (IgG(ALL)) and normal individuals (IgG(N)) by digoxigenin glycan enzyme assay, fluorimetric estimation, gas-liquid chromatography and lectin-binding assays demonstrated that disease-specific antibodies differ in content and nature as compared with normal controls. Enhanced amount of 9-OAcSA-specific IgG2 induced in ALL was unable to trigger activation of FcgammaR, the complement cascade and cell-mediated cytotoxicity, although its glycotope-binding ability remains unaffected. Interestingly, only IgG1(N) emerged as the potent mediator of cell-mediated cytotoxicity, complement fixation and activator of effector cells through FcgammaR. In ALL, the observed subclass switching of anti-9-OAcSGs to IgG2, alteration in their glycosylation profile along with impairment of a few Fc-glycosylation-sensitive effector functions hints toward a disbalanced homeostasis, thereby evading the host defense. These findings justify further evaluation of the mechanism for functional unresponsiveness of antibodies and production of 9-OAcSA-specific chimeric antibodies with normal Fc domain for therapeutic applications. DOI: 10.1093/intimm/dxh198 2005-02-01T00:00:00Z http://192.168.1.40:8080/xmlui/handle/123456789/2262 Tumor-induced dysfunction in T lymphocytes: increased sensitivity to apoptosis Finke, J. H.; Tannenbaum, C.; Storkus, W.; Rayman, P.; Das, Tanya; Biswas, K.; Richmond, A.; Moon, C.; Thornton, M.; Gill, I.; Novick, A.; Bukowski, R. DOI: 10.1007/s00120-004-0600-z 2004-09-01T00:00:00Z http://192.168.1.40:8080/xmlui/handle/123456789/2260 Effect of renal cell carcinomas on the development of type 1 T-cell responses( Conference Paper ) Rayman, P.; Wesa, A. K.; Richmond, A. L.; Das, Tanya; Biswas, K.; Raval, G.; Storkus, W. J.; Tannenbaum, C.; Novick, A.; Bukowski, R.; Finke, J.; Yang, J.; Atkins, M. Purpose: We reported that in renal cell carcinoma patients with active disease, T-cell reactions to the tumor-associated antigens MAGE-6 and EphA2 are highly skewed toward T(H)2-type cytokine responses [interleukin (IL) 5]. Herein, we determined whether tumor-derived products, including gangliosides isolated from renal cell carcinoma patients, participate in the down-regulation of type 1 T-cell responses. Experimental Design: T cells from healthy volunteers or renal cell carcinoma patients were cultured in the presence and absence of supernatants derived from renal cell carcinoma explants or with gangliosides isolated from those tumor supernatants. T cells were stimulated or not with either autologous dendritic cells pulsed with superantigen (Staphylococcus enterotoxin B) or with phorbol 12-myristate 13-acetate and ionomycin and then were assessed for type 1 or type 2 responses (cytokine production and gene expression) and apoptosis. Results: Tumor supernatants efficiently inhibited the T(H)1-type responses [interferon (IFN) gamma] of T cells stimulated with either S. enterotoxin B or phorbol 12-myristate 13-acetate and ionomycin but had no inhibitory effect on activated T-cell production of type 2 cytokines (IL-4, IL-5, and IL-10). Likewise, IFN-gamma mRNA and protein production were inhibited when T cells were cocultured with either renal cell carcinoma supernatant-derived gangliosides or a commercial source of purified GD1a. It was also determined that gangliosides impair type 1 responses by inducing apoptosis of activated T cells. Conclusions: We propose that renal cell carcinoma-derived tumor products such as gangliosides can induce a type 2 bias in antitumor immunity by initiating apoptosis in the IFN-gamma-producing type 1 effector cells. This represents a relevant mechanism by which renal cell carcinoma can inhibit protective antitumor immunity. DOI: 10.1158/1078-0432.CCR-050011 2004-09-15T00:00:00Z