title: IRX-2, a novel immunotherapeutic, protects human T cells from tumor-induced cell death.
abstract: IRX-2 is a cytokine-based biologic agent that has the potential to enhance antitumor immune responses. We investigated whether IRX-2 can protect T cells from tumor-induced apoptosis. Tumor-derived microvesicles (MV) expressing FasL were purified from supernatants of tumor cells and incubated with activated CD8(+) T cells. MV induced significant CD8(+) T-cell apoptosis, as evidenced by Annexin binding (64.4+/-6.4%), caspase activation (58.1+/-7.6%), a loss of mitochondrial membrane potential (82.9+/-3.9%) and DNA fragmentation. T-cell pretreatment with IRX-2 prevented apoptosis. IRX-2-mediated cytoprotection was dose and time dependent and was comparable to effects of IL-2, IL-7 or IL-15. IRX-2 prevented MV-induced downregulation of JAK3 and TCRzeta chain and induced STAT5 activation in T cells. IRX-2 prevented MV-induced Bax and Bim upregulation (P<0.005-0.05), prevented cytochrome c release and Bid cleavage, and concurrently restored the expression of Bcl-2, Bcl-xL, FLIP and Mcl-1 (P<0.005-0.01) in T cells. In addition, IRX-2 reversed MV-induced inhibition of the PI3K/Akt pathway. An Akt inhibitor (Akti-1/2) abrogated protective effects of IRX-2, suggesting that Akt is a downstream target of IRX-2 signaling. Thus, ex vivo pretreatment of CD8(+) T cells with IRX-2 provided potent protection from tumor-induced apoptosis. IRX-2 application to future cancer biotherapies could improve their effectiveness by bolstering T-cell resistance to tumor-induced immunosuppression.
authors.affiliation: University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213, USA.
authors.forename: M
authors.initials: M
authors.lastname: Czystowska
authors.forename: J
authors.initials: J
authors.lastname: Han
authors.forename: M J
authors.initials: MJ
authors.lastname: Szczepanski
authors.forename: M
authors.initials: M
authors.lastname: Szajnik
authors.forename: K
authors.initials: K
authors.lastname: Quadrini
authors.forename: H
authors.initials: H
authors.lastname: Brandwein
authors.forename: J W
authors.initials: JW
authors.lastname: Hadden
authors.forename: K
authors.initials: K
authors.lastname: Signorelli
authors.forename: T L
authors.initials: TL
authors.lastname: Whiteside
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D000072224:Bcl-2-Like Protein 11; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects* / Q000276:immunology; D045744:Cell Line, Tumor; D016207:Cytokines / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D053616:Janus Kinase 3 / Q000378:metabolism; D019169:Jurkat Cells; D008565:Membrane Proteins / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D050799:STAT5 Transcription Factor / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology; D013997:Time Factors; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; C000606775:BCL2L11 protein, human; D000072224:Bcl-2-Like Protein 11; D016207:Cytokines; C114857:IRX 2; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D050799:STAT5 Transcription Factor; D051028:bcl-2-Associated X Protein; D019869:Phosphatidylinositol 3-Kinases; C507933:JAK3 protein, human; D053616:Janus Kinase 3; D051057:Proto-Oncogene Proteins c-akt