Deletion of the <i>TMEM30A</i> gene enables leukemic cell evasion of NK cell cytotoxicity.

Abstract

Natural killer (NK) cell immunotherapy has gained attention as a promising strategy for treatment of various malignancies. In this study, we used a genome-wide CRISPR screen to identify genes that provide protection or susceptibility to NK cell cytotoxicity. The screen confirmed the role of several genes in NK cell regulation, such as genes involved in interferon-γ signaling and antigen presentation, as well as genes encoding the NK cell receptor ligands B7-H6 and CD58. Notably, the gene <i>TMEM30A</i>, encoding CDC50A-beta-subunit of the flippase shuttling phospholipids in the plasma membrane, emerged as crucial for NK cell killing. Accordingly, a broad range of <i>TMEM30A</i> knock-out (KO) leukemia and lymphoma cells displayed increased surface levels of phosphatidylserine (PtdSer). <i>TMEM30A</i> KO cells triggered less NK cell degranulation, cytokine production and displayed lower susceptibility to NK cell cytotoxicity. Blockade of PtdSer or the inhibitory receptor TIM-3, restored the NK cell ability to eliminate <i>TMEM30A</i>-mutated cells. The key role of the TIM-3 - PtdSer interaction for NK cell regulation was further substantiated by disruption of the receptor gene in primary NK cells, which significantly reduced the impact of elevated PtdSer in <i>TMEM30A</i> KO leukemic cells. Our study underscores the potential significance of agents targeting the interaction between PtdSer and TIM-3 in the realm of cancer immunotherapy.