Exosomal METTL16 from mesenchymal stem cells promotes malignant progression and M2 macrophage polarization in acute...

Acute myeloid leukemia (AML) progression relies on complex crosstalk with the bone marrow microenvironment, particularly M2 macrophage polarization. Exosomes mediate intercellular communication, while N6-methyladenosine (m6A) modifications drive tumor malignancy. However, the role of exosomal m6A regulators in coordinating AML progression and macrophage polarization remains unclear.

Integrated bioinformatics combining transcriptomics, weighted gene co-expression network analysis (WGCNA), and single-cell RNA sequencing identified key genes in AML. mRNA and protein expression levels were detected by quantitative real-time polymerase chain reaction and Western blotting assays. In vitro assays evaluated AML cell proliferation, apoptosis, oxidative stress, and drug sensitivity. Macrophage polarization was assessed using Transwell co-culture systems. Exosome isolation, m6A RNA immunoprecipitation, RNA immunoprecipitation, and dual-luciferase reporter assays elucidated the underlying molecular mechanism. A xenograft mouse model assay was performed to analyze the effects of methyltransferase-like 16 (METTL16)-deficient exosomes and glutathione peroxidase 1 (GPX1) overexpression on tumor formation.

GPX1 was identified as a hub gene in AML. Its expression was significantly upregulated in AML and closely linked to monocyte-macrophage differentiation. Functionally, GPX1 silencing suppressed AML cell malignancy, induced oxidative stress, enhanced cytarabine sensitivity, and inhibited M2 polarization (P < 0.05). Mechanistically, METTL16 mediated GPX1 m6A modification, which was recognized by insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) to stabilize GPX1 mRNA (P < 0.05). Notably, METTL16 was highly enriched in both AML patient serum-derived exosomes and AML-mesenchymal stem cell (MSC)-derived exosomes (P < 0.05). METTL16-deficient exosomes effectively reversed these pro-tumoral effects both in vitro and in vivo by downregulating GPX1 (P < 0.05).

Exosomal METTL16 from AML-MSCs plays a crucial role in promoting leukemic cell survival and M2 polarization. Targeting this axis may provide a potential theoretical foundation to reverse M2 macrophage polarization and inhibit AML progression.