FOXO3 Deficiency in Neutrophils Drives Colonic Inflammation and Tumorigenesis
Inflammatory bowel disease (IBD), characterized by infiltration of polymorphonuclear neutrophils (PMNs), increases the risk of colon cancer. PMN activation corresponds to accumulation of their intracellular Lipid Droplets (LDs). As increased LDs are negatively regulated by transcription factor FOXO3, our aim is to determine the significance of this regulatory network in PMN-mediated IBD and tumorigenesis. Affected tissue of IBD and colon cancer patients, colonic and infiltrated immune cells, have increased LDs' coat protein, PLIN2. Mouse peritoneal PMNs with increased LDs and FOXO3 deficiency have elevated transmigratory activity. Transcriptomic analysis of these FOXO3-deficient PMNs showed differentially expressed genes (DEGs; FDR < 0.05) involved in metabolism, inflammation, and tumorigenesis. Upstream regulators of these DEGs, similar to colonic inflammation and dysplasia in mice, were linked to IBD and human colon cancer. Additionally, a transcriptional signature representing FOXO3-deficient PMNs (PMN-FOXO3389) separated transcriptomes of affected tissue in IBD (p=0.00018) and colon cancer (p=0.0037) from control. PMN-FOXO3389 predicted colon cancer invasion (lymphovascular p= 0.015; vascular p= 0.046; perineural p=0.03), and poor survival. Validated DEGs from PMN-FOXO3389 (P2RX1, MGLL, MCAM, CDKN1A, RALBP1, CCPG1, PLA2G7) are involved in metabolism, inflammation, and tumorigenesis (p<0.05). These findings highlight the significance of LDs and FOXO3-mediated PMN functions that promote colonic pathobiology. Overall design: Comparative gene expression profiling analysis of RNA-seq data for FOXO3 KO Neutrophils (PMNs) compared to WT.