The main phenolic secoiridoid oleuropein and active constituent from olive tree (Olea europaea, Oleaceae), has demonstrated anti-inflammatory properties in intestinal inflammation and anti-tumoral effects in different cancer cells. In this study, we evaluated the chemoprevention of oleuropein in a model of azoxymethane (AOM)/Dextran sulfate sodium (DSS)-induced colorectal cancer (CRC) in C57BL/6 mice and the modulatory effect on the Th17 response in DSS acute colitis.Methods and results:
Oleuropein protected from AOM/DSS-induced CRC by improving clinical symptoms, disease activity index score as well as suppressed the growth and multiplicity of colonic tumors. Treatment with oleuropein reduced intestinal IL-6, IFN-γ, TNF-α, and IL-17A concentration, and decreased cyclooxygenase-2, Bax and proliferating cell nuclear antigen protein expression. Western blot analysis also showed a markedly downregulation of CRC-related pathways as nuclear factor-κB (NF-κB), Wnt/β-catenin, phosphatidylinositol-3-kinase (P3IK)/Akt, and signal transducer and activators of transcription (STAT)3. In DSS acute model, oleuropein inhibited Th17 response, by decreasing CD4+Rorγt+ IL-17+ IFN-γ+ T-cell subsets in the lamina propria, as well as IL-17A and IFN-γ expression.Conclusion:
Oleuropein as a dietary supplementation could be a promising protective agent against colitis-associated CRC.