Tumour‐macrophage crosstalk initiated by NFIC/METTL3 negative feedback loop via exosomal miR‐194‐5p promotes NSCLC progression

Background

The interplay between tumour cells and tumour‐associated macrophages (TAMs) within the tumour microenvironment is crucial for the progression of non‐small cell lung cancer (NSCLC). The underlying mechanisms involving RNA modification and exosomal communication remain incompletely understood.

Methods

Multiplex immunofluorescence and flow cytometry were performed to evaluate M2 macrophage polarization. Exosomes were isolated by ultracentrifugation and validated by transmission electron microscopy, nanoparticle tracking analysis, and exosomal marker blots. To investigate the molecular mechanism, methylated RNA immunoprecipitation (MeRIP)‐qPCR and dual‐luciferase reporter assays were used to validate m ⁶ A modification sites on NFIC and miR‐194‐5p; RNA immunoprecipitation (RIP) confirmed the interaction between ZNF106 and interleukin‐6 (IL‐6) mRNA; chromatin immunoprecipitation (ChIP) was employed to detect STAT3 binding to the METTL3 promoter. The in vivo function of the identified feedback loop was assessed using an orthotopic xenograft mouse model of NSCLC.

Results

A negative feedback loop between METTL3 and NFIC was demonstrated in NSCLC cells. METTL3 suppressed miR‐194‐5p expression and its loading into exosomes through m ⁶ A methylation. NSCLC‐derived exosomal miR‐194‐5p was internalized by macrophages and directly targeted ZNF106, thereby inhibiting M2 polarization. In macrophages, ZNF106 stabilized IL‐6 mRNA and promoted exosomal IL‐6 secretion, thereby activating the JAK2/STAT3 pathway and upregulating METTL3. This IL‐6‐driven METTL3 upregulation formed a positive feedback loop that sustains M2 polarization and tumour progression. In vivo disruption of this loop reduced tumour growth and metastasis.

Conclusions

These findings establish a closed regulatory circuit initiated by an NFIC/METTL3 negative feedback loop. In this circuit, METTL3‐mediated m ⁶ A modification of exosomal miR‐194‐5p in NSCLC cells derepresses ZNF106 expression in macrophages, leading to IL‐6 production that activates the JAK2/STAT3 pathway and upregulates METTL3 in tumour cells, thereby perpetuating M2 polarization and malignant progression. This circuitry offers potential nodes for therapeutic intervention in NSCLC.

Key points