MEX3A activates the JAK-STAT pathway to suppress NK cell cytotoxicity and accelerate lung adenocarcinoma progression

Abstract

Background: Therapeutic potential of natural killer (NK) cells is recognized in treating lung adenocarcinoma (LUAD), but impairment of NK cell functions in various cancers weakens anti-tumor capabilities. Uncovering molecular mechanisms is imperative for fortifying NK cells against degradation and for enhancing their cancer-inhibiting functions.

Methods: TCGA-LUAD database complemented by qRT-PCR presented MEX3A expression in LUAD. TIMER was employed to explore relationship between MEX3A levels and NK cell infiltration. In the co-culture system of LUAD and activated NK92 cells, CytoTox 96® assay was applied to gauge NK cell cytotoxicity. ELISA was used to quantify IFN-γ, Perforin, and Granzyme B in the supernatant. Flow cytometry assessed LUAD cell apoptosis. Single-gene enrichment analysis of MEX3A was performed with KEGG database. Western blot examined protein expression in JAK-STAT signaling. In vivo studies validated the role of MEX3A expression on tumorigenesis.

Results: MEX3A was upregulated in LUAD tissue and cells, negatively linked to NK cell infiltration levels. Gene set enrichment analysis pointed to influences of MEX3A expression on dynamics of JAK-STAT signaling. MEX3A overexpression in LUAD cells impaired NK cell cytotoxicity and cell apoptosis, and these effects were reversible by a JAK pathway inhibitor. Mouse studies illustrated that LUAD progression was curbed by MEX3A suppression, alongside an enhanced presence of NK cells within tumor microenvironment.

Conclusion: To synthesize our results, this study identified that MEX3A in LUAD promoted malignancy of the disease by enhancing JAK-STAT signaling, which in turn inhibited cytotoxic capabilities of NK cells, thus providing novel insights for LUAD immunotherapy.

Keywords: JAK-STAT signaling pathway; Lung adenocarcinoma; MEX3A; NK cells.