| 1. |
- Djerbi, M, et al.
(author)
-
The inhibitor of death receptor signaling, FLICE-inhibitory protein defines a new class of tumor progression factors
- 1999
-
In: The Journal of experimental medicine. - : Rockefeller University Press. - 0022-1007 .- 1540-9538. ; 190:7, s. 1025-1031
-
Journal article (peer-reviewed)abstract
- Death receptor–mediated apoptosis can be modulated by several antiapoptotic proteins, such as the FLICE (FADD [Fas-associated death domain]-like IL-1β–converting enzyme)-inhibitory proteins (FLIPs). The FLIP family includes both cellular and viral members. The Kaposi's sarcoma–associated herpesvirus protein (KSHV)-FLIP is expressed by human herpesvirus 8 (HHV-8), which is associated with malignancies such as Kaposi's sarcoma and certain lymphomas. In this paper, we demonstrate that KSHV-FLIP protects cells from Fas-mediated apoptosis by inhibiting caspase activation and permits clonal growth in the presence of death stimuli in vitro. Furthermore, we show that KSHV-FLIP can act as a tumor progression factor by promoting tumor establishment and growth in vivo. When injected into immunocompetent recipient mouse strains, murine B lymphoma cells (A20) transduced with KSHV-FLIP rapidly develop into aggressive tumors showing a high rate of survival and growth. The tumor-progressive activity of KSHV-FLIP is mediated by prevention of death receptor–induced apoptosis triggered by conventional T cells. Consequently, inhibitors of death receptor signaling can be regarded as a new class of tumor progression factors, and HHV-8–associated tumors may represent naturally occurring examples of the tumorigenic effect of such inhibitors.
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Rietz, C, et al.
(author)
-
Overexpression of Bcl-2 in T cells affects insulitis in the nonobese diabetic mouse
- 2003
-
In: Scandinavian Journal of Immunology. - : Wiley. - 0300-9475 .- 1365-3083. ; 57:4, s. 342-349
-
Journal article (peer-reviewed)abstract
- The nonobese diabetic (NOD) mouse is a useful model for human autoimmune diabetes. The gene for the anti-apoptotic protein Bcl-2 has previously been suggested as a probable susceptibility candidate for the NOD mouse disease. In this study, we investigated how overexpression of Bcl-2 in lymphocytes might affect insulitis in NOD mice. A bcl-2 transgene expressed constitutively under the SV40-promoter and the 5'Igh enhancer, Emu, was bred onto NOD background. Two bcl-2 transgenic NOD strains were produced and analysed, one with overexpression of Bcl-2 on only B cells and the other with overexpression of Bcl-2 on both B and T cells. Subsequent to verification of expression pattern and functionality of the transgene, insulitis intensity was investigated in different backcross generations of the two transgenic strains. Overexpression of Bcl-2 on both B and T cells leads to a statistically significant protection of the mice from insulitis compared with normal littermates. Overexpression of Bcl-2 on only B cells, on the other hand, does not have any statistically significant effect on insulitis. Possible mechanisms for the effect of Bcl-2 on insulitis in NOD mice are discussed.
|
|
| 5. |
- Screpanti, V, et al.
(author)
-
A central role for death receptor-mediated apoptosis in the rejection of tumors by NK cells
- 2001
-
In: Journal of immunology (Baltimore, Md. : 1950). - : The American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 167:4, s. 2068-2073
-
Journal article (peer-reviewed)abstract
- NK cells provide a line of defense against tumors and virus-infected cells that have lost the expression of one or more MHC class I isoforms. Here, we investigate whether inhibitors of apoptosis can block the rejection of tumors mediated by NK cells, by introducing the long form of Fas-associated death domain-like IL-1β-converting enzyme-associated inhibitory protein (FLIPL) and poxvirus cytokine response modifier A (CrmA) into the MHC class I-deficient T lymphoma cell line RMA-S. RMA-S cells do not normally express Fas in vitro, and it was previously postulated that the rejection of these tumors by NK cells is strictly perforin dependent. We show that perforin-deficient NK cells directly mediate Fas up-regulation on RMA-S cells and thereafter kill the cells in a Fas-dependent manner, and that RMA-S FLIPL and RMA-S CrmA are protected from such killing. When injected in immunocompetent recipients, RMA-S cells up-regulate Fas, rendering in vivo-passed mock-transduced cells sensitive to Fas-mediated apoptosis. Moreover, RMA-S FLIPL and RMA-S CrmA cells establish aggressive tumors, in contrast to RMA-S mock cells that are rejected. These results demonstrate that FLIPL and CrmA function as tumor progression factors by protecting MHC class I-deficient tumors from rejection mediated by NK cells. Moreover, our data indicate that death receptor-mediated apoptosis has a more prominent role in the clearance of NK-sensitive tumors than previously suggested.
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
|
|
