Macrophage-Derived Exosomes Promoted the Development and Stemness of Inflammatory Bowel Disease-Related Colorectal Cancer via nuclear paraspeckle assembly transcript 1-Mediated miRNA-34a-5p/phosphoprotein enriched in astrocytes 15 Axis

Background: Inflammatory bowel disease (IBD) is closely associated with the development of colorectal cancer (CRC) due to the chronic inflammatory response. Macrophages play critical roles in regulating the microenvironment to facilitate tumor progression. Exosomes are key modulators for the communication between macrophages and tumor cells. The mechanism of macrophage-derived exosomes in IBD-related CRC development remains unclear.

Methods: The macrophages were isolated using fluorescence activating cell sorter (FACS). The RNA and protein expressions in exosomes and CRC cells were examined by quantitative real-time polymerase chain reaction and western blot assays, respectively. CRC cell development was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, BrdU staining, Transwell assay, and spheroid formation assay. The level of stemness was determined by detecting the proportion of leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5)-positive CRC cells and the expression of LGR5, CD133, and CD44. Molecular interaction experiments were done using luciferase reporter assay and RNA immunoprecipitation assay. Xenograft tumor model in vivo and immunohistochemistry were used to observe the pathological changes.

Results: Macrophage-derived exosomes from IBD-related CRC tissues were enriched with nuclear paraspeckle assembly transcript 1 (NEAT1) and able to promote the progression and stemness of CRC both in vitro and in vivo. The exosomal NEAT1 could sponge miR-34a-5p, leading to the restoration of PEA15 expression in CRC cells and promoting the development of CRC. Inhibition of NEAT1 in exosomes could effectivity inhibit the tumor growth in the CRC xenograft model.

Conclusions: These findings provide novel insights into how macrophages affect CRC development and highlight exosomal NEAT1 as a therapeutic target for CRC treatment.