Development of a novel in vitro screening method using genetically modified NK-92 cells against various tumor cells

Official URL: https://risc01.sabanciuniv.edu/record=b2486374 _(Table of contents)

Natural killer (NK) cells of the innate immune system are recognized for their ability to potently kill tumor cells. NK cell-mediated lysis is maintained by an intricate balance between several activating and inhibitory receptors that either trigger or dampen effector functions upon ligand engagement. In this study, we aim to dissect this complex balance by developing a cell-based screening tool to identify receptor specific anti-tumor responses. As the character of the heterogeneous tumor cell populations differs among patients, such a tool may be instrumental in developing patient-tailored cancer immunotherapies. Genes encoding 20 NK cell surface receptors were cloned into lentiviral vectors for genetic modification of the NK-92 cell line. Genetically modified (GM) NK-92 cells were enriched and overexpression of receptors was confirmed by flow cytometry. We analyzed the effector functions of all GM NK-92 cells against human cancer cell lines as well as against primary human sarcoma explants. Overall, genetic modifications did not hamper cytotoxic capacity of GM NK-92 cells; rather induced enhanced tumor cell targeting by receptors such as DNAM-1 and NKG2D. We further confirmed that this response was indeed DNAM-1 or NKG2D-dependent by using blocking antibodies. We also evaluated the synergistic response of prominent receptors in triggering degranulation and cytotoxicity by co-expressing DNAM-1 and NKG2D. Our results show the feasibility of an in vitro genetic screening approach to identify response-triggering receptors in genetically modified NK cells expressing different activating receptors. This tool has the potential to rapidly identify patient-specific targets for adoptive immunotherapy of cancer