Adoptive transfer of engineered NK cells, one of clinical approaches to fight
cancer, is gaining great interest in the last decade. However, the development of new strategies is needed to improve clinical efficacy and safety of NK cell-based
immunotherapy. NK cell-mediated recognition and lysis of
tumor cells are strictly dependent on the expression of
ligands for NK cell-activating receptors NKG2D and DNAM-1 on
tumor cells. Of note, the PVR/CD155 and
Nectin-2/CD112
ligands for DNAM-1 are expressed primarily on solid
tumor cells and poorly expressed in normal tissue cells. Here, we generated human NK cells expressing either the full length DNAM-1 receptor or three different DNAM-1-based chimeric receptor that provide the expression of DNAM-1 fused to a costimulatory molecule such as 2B4 and CD3ζ chain. Upon transfection into primary human NK cells isolated from healthy donors, we evaluated the surface expression of DNAM-1 and, as a functional readout, we assessed the extent of degranulation, cytotoxicity and the production of IFNγ and TNFα in response to human leukemic K562 cell line. In addition, we explored the effect of
Nutlin-3a, a MDM2-targeting
drug able of restoring p53 functions and known to have an immunomodulatory effect, on the degranulation of DNAM-1-engineered NK cells in response to human
neuroblastoma (NB) LA-N-5 and SMS-KCNR cell lines. By comparing NK cells transfected with four different plasmid vectors and through blocking experiments, DNAM-1-CD3ζ-engineered NK cells showed the strongest response. Furthermore, both LA-N-5 and SMS-KCNR cells pretreated with
Nutlin-3a were significantly more susceptible to DNAM-1-engineered NK cells than NK cells transfected with the empty vector. Our results provide a proof-of-concept suggesting that the combined use of DNAM-1-chimeric receptor-engineered NK cells and
Nutlin-3a may represent a novel therapeutic approach for the treatment of solid
tumors, such as NB, carrying dysfunctional p53.