LEF1 activates a central memory-like program in human NKT cells

Abstract

Abstract Vα24-invariant natural killer T cells (NKTs) possess potent antitumor activity that can be exploited for use in cancer immunotherapy. We recently demonstrated that the CD62L+ NKT subset persists longer and mediates more potent antitumor activity in vivo than its CD62L− counterpart; as such, CD62L+ NKTs are crucial to maximizing the therapeutic efficacy of NKTs. Key factors involved in transcriptional control of the CD62L+ central memory-like program in NKTs remain largely undefined. To address this gap, we performed comparative gene expression analysis in CD62L+ and CD62L− NKTs and found that LEF1, which encodes a mediator of Wnt/β-catenin signaling, was the top overexpressed gene in the positive subset. We also found that LEF1 protein expression was largely restricted to CD62L+ primary human NKTs and was associated with increased expression of Wnt target genes. While CRISPR-Cas9-mediated knockout of LEF1 expression did not impact CD62L+ cell numbers after initial ex vivo expansion, it did significantly reduce the frequency of these cells after antigenic restimulation. On the other hand, treatment with Wnt/β-catenin signaling activator TWS119 or Wnt3a ligand increased CD62L+ NKT cell frequency. Combined treatment of TWS119 with IL-21, which selectively protects the CD62L+ subset from apoptosis, resulted in significantly higher CD62L+ cell numbers than each single agent alone. These results identify LEF1 as a key transcriptional activator of the central memory-like program in CD62L+ NKTs and pave the way for targeted pharmacological enhancement of NKT cell-based cancer immunotherapy.