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Cancer Immunol Immunother. 2011 Apr;60(4):495-506. doi: 10.1007/s00262-010-0951-9. Epub 2010 Dec 23.

Mechanisms of T-cell protection from death by IRX-2: a new immunotherapeutic.

Author information

1
Research Pavilion at Hillman Cancer Center, University of Pittsburgh Cancer Institute, 5117 Centre Avenue, Suite 1.27, Pittsburgh, PA 15213-1863, USA.

Abstract

OBJECTIVES:

IRX-2 is a novel immunotherapeutic containing physiologic quantities of several cytokines which protects human T lymphocytes from tumor-induced or drug-induced apoptosis. Here, we investigate the mechanisms responsible for IRX-2-mediated protection of T lymphocytes exposed to tumor-derived microvesicles (TMV).

METHODS:

Jurkat cells or primary human T cells ± IRX-2 were co-incubated with TMV and then examined by flow cytometry or Western blots for expression of molecules regulating cell survival (FLIP, Bcl-2, Bcl-xL, Mcl-1) or death (Fas, caspase 8, caspase 9, Bax, Bid). ANX V binding, caspase activation or cytochrome c release were also measured ± cycloheximide (CHX) or ± the Akt-specific inhibitor. Jurkat cells transfected with the cFLIP gene were used to evaluate the role of cFLIP in IRX-2-mediated protection. Effects of CHX on IRX-2-mediated protection and activation of NF-κB upon the TMV/IRX-2 treatment were also measured.

RESULTS:

IRX-2 protected T cells from apoptosis by preventing Fas overexpression induced by TMV and blocking caspase 8 activation by up-regulating cFLIP. Jurkat cells overexpressing cFLIP were more resistant to TMV-induced apoptosis than the mock-transfected cells (p < 0.02). Signaling via the PI3K/Akt pathway, IRX-2 corrected the imbalance of pro- versus anti-apoptotic proteins induced by TMV and promoted NF-κB translocation to the nucleus. CHX abolished IRX-2-mediated protection in T cells, suggesting that IRX-2 induces de novo synthesis of one or more proteins that are required for protection.

CONCLUSIONS:

This biologic may be therapeutically useful for protection of activated T cells from tumor-induced immune suppression and death.

PMID:
21181158
PMCID:
PMC3708464
DOI:
10.1007/s00262-010-0951-9
[Indexed for MEDLINE]
Free PMC Article

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