title: Live cell evaluation of granzyme delivery and death receptor signaling in tumor cells targeted by human natural killer cells.
abstract: Growing interest in natural killer (NK) cell-based therapy for treating human cancer has made it imperative to develop new tools to measure early events in cell death. We recently demonstrated that protease-cleavable luciferase biosensors detect granzyme B and pro-apoptotic caspase activation within minutes of target cell recognition by murine cytotoxic lymphocytes. Here we report successful adaptation of the biosensor technology to assess perforin-dependent and -independent induction of death pathways in tumor cells recognized by human NK cell lines and primary cells. Cell-cell signaling via both Fc receptors and NK-activating receptors led to measurable luciferase signal within 15 minutes. In addition to the previously described aspartase-cleavable biosensors, we report development of granzyme A and granzyme K biosensors, for which no other functional reporters are available. The strength of signaling for granzyme biosensors was dependent on perforin expression in IL-2-activated NK effectors. Perforin-independent induction of apoptotic caspases was mediated by death receptor ligation and was detectable after 45 minutes of conjugation. Evidence of both FasL and TRAIL-mediated signaling was seen after engagement of Jurkat cells by perforin-deficient human cytotoxic lymphocytes. Although K562 cells have been reported to be insensitive to TRAIL, robust activation of pro-apoptotic caspases by NK cell-derived TRAIL was detectable in K562 cells. These studies highlight the sensitivity of protease-cleaved luciferase biosensors to measure previously undetectable events in live cells in real time. Further development of caspase and granzyme biosensors will allow interrogation of additional features of granzyme activity in live cells including localization, timing, and specificity.
authors.affiliation: Division of Allergy/Immunology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH;
authors.forename: Alexandra C
authors.identifier: http://orcid.org/0000-0002-7216-9302
authors.initials: AC
authors.lastname: Vrazo
authors.affiliation: Division of Allergy/Immunology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH;
authors.forename: Adrianne E
authors.identifier: http://orcid.org/0000-0002-3656-7055
authors.initials: AE
authors.lastname: Hontz
authors.affiliation: Division of Allergy/Immunology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH;
authors.forename: Sarah K
authors.initials: SK
authors.lastname: Figueira
authors.affiliation: Promega Corp, Madison, WI; and.
authors.forename: Braeden L
authors.initials: BL
authors.lastname: Butler
authors.affiliation: Division of Allergy/Immunology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH;
authors.forename: Julie M
authors.initials: JM
authors.lastname: Ferrell
authors.affiliation: Promega Corp, Madison, WI; and.
authors.forename: Brock F
authors.initials: BF
authors.lastname: Binkowski
authors.affiliation: Division of Allergy/Immunology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH;
authors.forename: Jinzhu
authors.initials: J
authors.lastname: Li
authors.affiliation: Division of Allergy/Immunology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH.
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Risma
mesh_terms: D017209:Apoptosis / Q000502:physiology*; D015374:Biosensing Techniques; D020169:Caspases / Q000276:immunology; D045744:Cell Line, Tumor; D004789:Enzyme Activation / Q000502:physiology; D005434:Flow Cytometry; D053804:Granzymes / Q000008:administration & dosage / Q000276:immunology*; D006801:Humans; D015151:Immunoblotting; D007167:Immunotherapy / Q000379:methods*; D019169:Jurkat Cells; D020014:K562 Cells; D007694:Killer Cells, Natural / Q000276:immunology*; D009369:Neoplasms / Q000276:immunology*; D011994:Recombinant Proteins; D014162:Transfection
chemical_list: D011994:Recombinant Proteins; D053804:Granzymes; D020169:Caspases