M2-polarized tumor-associated macrophage-secreted exosomal lncRNA NEAT1 upregulates galectin-3 by recruiting KLF5 and promotes HCC immune escape

Abstract

HCC cell immune escape is a critical element in the evolution of HCC malignancy. Herein, the regulatory mechanism of lncRNA NEAT1 in regulating HCC immune escape was investigated. Exosomes were isolated from M2 TAMs using ExoQuick-TC. Then, HCC cells were incubated with M2 TAMs-derived exosomes (M2-exos). The activation of perforin⁺CD8⁺ T cells was measured using flow cytometry. The secretion of IFN-γ was assessed using ELISA. Cell viability and migration were detected using CCK8 and Transwell assays, respectively. RIP and RNA pull-down assays were used to investigate the link between NEAT1 and KLF5. ChIP and dual-luciferase reporter assays were used to investigate the interaction between KLF5 and the LGALS3 promoter. Our results showed that NEAT1, KLF5 and galectin-3 were overexpressed in HCC tissues. M2-exos treatment promoted HCC proliferation, migration, and immune escape. It was found that NEAT1 was enriched in M2-TAMs and M2-exos. M2-exos facilitated HCC immune escape, whereas NEAT1 silencing reversed this effect. NEAT1 upregulated galectin-3 in HCC cells by recruiting KLF5. Mechanically, M2-TAM-derived exosomal NEAT1 induced HCC immune escape by upregulating KLF5/galectin-3 axis. M2-TAM-derived exosomal NEAT1 upregulated galectin-3 in HCC cells by recruiting KLF5 to promote perforin⁺CD8⁺ T cell depletion and further accelerate HCC immune escape.

Keywords: KLF5; NEAT1; exosomes; galectin-3; hepatocellular carcinoma; immune escape; tumor‐associated macrophages.