Role of exosomal ncRNAs released by M2 macrophages in tumor progression of gastrointestinal cancers

Macrophages (MΦs) type 2 (M2) play crucial roles in the pathogenesis of gastrointestinal cancers (GIC) by enhancing tumor progression, invasion, and metastasis. Polarized M2 has been linked to the increase of GIC tumorigenesis and drug resistance. Several studies reported that M2-derived exosomal non-coding RNAs (Exos-ncRNAs) play pivotal roles in the modulation of the GIC tumor microenvironment (TME) and mostly promote drug resistance and immunosuppression. The impact of M2-Exos-ncRNAs is attributed to altered signaling pathways, enhancement of immunoregulatory mechanisms, and post-transcriptional modulation. Recent studies described novel targets in M2-TAMs-derived Exos-ncRNAs and potential promising clinical outcomes such as inhibiting tumor formation, invasion, and metastasis. Highlighting current knowledge of M2-Exos-ncRNAs involved in GIC pathogenesis and immunomodulation would thus be a significant contribution to improving clinical outcomes. In this review, we summarize recent updates on the role of M2-TAMs-Exos-ncRNAs in GIC pathogenesis, immunosuppression, and drug resistance. A deep understanding of M2-TAMs-derived Exos-ncRNAs could help to identify potential biomarkers and therapeutic targets.