EP300 promotes macrophage M2 polarization in diffuse large B-cell lymphoma through the NF-κB/CXCR4 axis

Abstract Diffuse large B-cell lymphoma (DLBCL) is the most common aggressive non-Hodgkin lymphoma, and the immunosuppressive tumor microenvironment (TME) contributes to its progression and chemoresistance. EP300 (p300) is a histone acetyltransferase and general transcriptional coactivator that is recurrently dysregulated in B-cell lymphomas, yet its role in shaping the DLBCL immune microenvironment remains unclear. Here we show that EP300 is overexpressed in DLBCL and that high EP300 expression correlates with poor overall survival. CRISPR/Cas9-mediated knockout of EP300 in DLBCL cells suppressed proliferation, promoted apoptosis, and inhibited subcutaneous xenograft growth. Integrative label-free quantitative proteomics and RNA sequencing revealed that EP300 knockout globally suppressed immune-related pathways, most prominently NF-κB signaling, and identified CXCR4 as the sole membrane receptor consistently downregulated at both the protein and mRNA levels. Mechanistically, EP300 knockout reduced phosphorylation of p65 and IκBα, decreased expression of the NF-κB target gene CXCR4 and of the M2-polarizing cytokines CSF1, CCL2 and IL-10, and diminished their secretion. Conditioned-medium and co-culture experiments demonstrated that these EP300-dependent soluble factors shape macrophage polarization: EP300 knockout shifted macrophages toward a CD86-high/CD206-low phenotype, and this effect showed cell-context dependence. Collectively, these findings identify an EP300–NF-κB–CXCR4 axis that sustains an M2-polarized microenvironment in DLBCL and nominate EP300 as a candidate therapeutic target for high-EP300 DLBCL.