Abstract 4450: SOX4 promotes tumor development and immune evasion via disruption of zinc homeostasis between nasopharyngeal carcinoma cells and T cells

Abstract

<p>Background: Nasopharyngeal carcinoma (NPC) is a highly undifferentiated squamous malignancy with dense infiltration of dysfunctional T cells that is endemic in East and Southeast Asia. Based on multicentral single-cell RNA sequencing (scRNA-seq) analysis, we have identified SRY-Box Transcription Factor 4 (SOX4), an essential developmental transcription factor, is specifically and highly expressed by NPC cells and contributes to tumor growth and distant metastasis. SOX4 upregulation also promotes ZIP14-mediated intracellular zinc uptake, leading to competitive deprivation of free zinc in the tumor microenvironment (TME), which inhibits zinc-dependent T cell receptor (TCR) activation. Thus, our study provides experimental insights into how NPC develops and evades immune surveillance.</p><p>Methods: scRNA-seq data and bulk RNA-Seq data from our lab and GEO database were integrated and analyzed on a bioinformatic basis. Immunohistochemistry staining was performed to validate the SOX4 protein level in an independent clinical cohort. Cell lines, patient-derived xenografts, and humanized mouse models were generated to evaluate the in vitro and in vivo function of SOX4. Flow cytometry was used for T-cell immunophenotyping. Immunoprecipitation was used to study protein-DNA interaction. The dual-luciferase reporter assay was utilized to demonstrate the transcriptional regulation of SOX4 on the ZIP14 promoter. qRT-PCR, immunoblotting, and immunofluorescence staining were also employed for functional studies.</p><p>Result: Our transcriptome analysis showed SOX4 was frequently overexpressed by NPC cells, compared to infiltrating immune and stromal cells. Increasing SOX4 expression in normal nasopharyngeal epithelial cells enhanced proliferation, stemness, migration, and invasion. SOX4 also transcriptionally upregulated ZIP14 in NPC cells which promoted the uptake of free zinc from the TME. Thus, competitive deprivation of zinc between NPC cells and T cells in the TME inhibited TCR signaling and T-cell cytotoxicity, leading to NPC immune evasion.</p><p>Conclusion: This study reveals the SOX4-ZIP14-Zinc axis as a vital mechanism for simultaneously inducing tumor development and immunosuppression in the NPC microenvironment. Therapeutic inhibition of SOX4 or ZIP14 is a new strategy for NPC patients and potentially synergizes with PD-1/PD-L1 blockades to overcome immunosuppressive signals in the TME.</p>