Background: Inflammatory processes are pivotal pathogenic factors in colorectal cancer. NR4A1 receptors are emerging as regulators, concurrently repressing pro-inflammatory processes while activating resolution pathways. Whether this could improve cancer-related immune dysregulation is unknown.
Methods: Tumour and normal control tissue (n=20) obtained from patients undergoing colorectal resection were exposed to a NR4A1 agonist [cytosporone B (CsnB) 4–100 µM] ex vivo. The supernatant was collected and RNA was extracted from tissues at 8 hours. A cytokine/chemokine array was used to examine 104 secreted proteins associated with tumour inflammation, angiogenesis, fibrosis and growth factors. Quantitative enzyme-linked immunosorbent assay (ELISA) and qRT-PCR were used. Viability studies were performed on colorectal cancer cell lines for toxicity experiments.
Results: Cytokine/chemokine array analysis revealed 50/104 were increased in tumours including inflammatory (IL-8, TNF-α), angiogenic factors (angiopoietin 1, vascular endothelial growth factor), and growth factors (fibroblast growth factor 7, leukemia inhibitory factor). Of those, 30/50 were repressed by ≥50% by the NR4A1 agonist. Multiple targets identified from the array were confirmed using quantitative ELISA and/or qRT-PCR including cytokines (e.g., IL-8, TNF-α, IL-23, IL-6), and chemokines (e.g., CCL3, CCL4, CCL20). Viability studies confirmed that CsnB is non-toxic.
Conclusions: Activation of an orphan nuclear receptor (NR4A1) represses pro-tumourogenic mediators such as cytokines, chemokines, growth factors, and angiogenic factors.
