DNA damage and apoptosis in blood neutrophils of inflammatory bowel disease patients and in Caco-2 cells in vitro exposed to betanin.

Abstract

Inflammatory bowel diseases (IBD) are chronic, relapsing, inflammatory disorders of the gastrointestinal tract, and continuing colonic inflammation is considered an important risk factor in the development of colorectal cancer. Our previous studies showed that beetroot (Beta vulgaris var. rubra) products and their major component betanin modulate the reactive oxygen species (ROS) production and DNA damage in 12-O-tetradecanoylphorbol 13-acetate (TPA) stimulated human polymorphonuclear neutrophils of healthy volunteers. The aim of the present study was to evaluate the effects of betanin on the oxidative DNA damage and apoptosis in neutrophils isolated from blood of patients with inflammatory bowel disease--ulcerative colitis (UC) and Crohn's disease (CD). The results were compared with those obtained in colon carcinoma-derived Caco-2 cells. Betanin treatment at the concentration of 100 μM for 24 h increased DNA damage assessed by comet assay in IBD patients' neutrophils. A similar effect although less pronounced was observed in Caco-2 cells. Treatment of Caco-2 cells with H2O2 caused a 4-fold increase of DNA strand breaks in comparison to untreated cells, but pre-treatment with betanin reduced DNA damage in these cells. Betanin also induced procaspase-3 cleavage and caspase-3 activity accompanied by the loss of mitochondrial transmembrane potential, indicating its pro-apoptotic activity. These results suggest that betanin may support mechanisms that lead to the release of ROS and apoptotic cell death. In this way betanin may exert anti-inflammatory and potentially cancer preventive activity.