Abstract A37: A study on the mechanism of chemoprevention by celecoxib and fish oil in experimental mammary carcinogenesis

Abstract

Abstract Background: Cyclooxygenase (COX)-2 inhibitor, celecoxib and n-3 poly unsaturated fatty acid (PUFA) rich fish oil has been reported to have a synergistic chemopreventive effect on colon and breast cancer in animal models and this effect may be mediated through alteration in apoptosis and cell cycle. Therefore, the present study was designed to understand the mechanism of action of this combinatorial strategy in 7,12-Dimethylbenz(a) anthracene (DMBA) induced mammary carcinogenesis. Study Design: Female Wistar rats were distributed into six groups: group-1 (vehicle treated), group-2 (DMBA treated), group-3 (20mg/kg body weight celecoxib + DMBA), group-4 (0.5 ml fish oil + DMBA), group-5 (20 mg/kg body weight celecoxib+0.5 ml fish oil) and group-6 (20 mg/kg body weight celecoxib+0.5 ml fish oil + DMBA). The animals were pretreated with the respective dose regimens orally for one week prior to the DMBA (15mg) dose. The animals were subsequently maintained for 90 days and then sacrificed. The levels of reactive oxygen species (ROS) by 2’,7’-dichlorofluorescein diacetate (DCFH-DA), intracellular Ca2+ by fluo-3-penta-acetoxymethylester (fluo-3-AM) dye, p53 by monoclonal antibody and mitochondrial membrane potential (MMP) by 5,5,6,6-tetrachloro-1,1,3,3-tetraethylbenzamidazolo-carbocyanin iodide (JC-1) dye were estimated in isolated mammary epithelial cells. Results: A significant increase in ROS, intracellular calcium and p53 levels and a decrease in MMP were observed in DMBA treated rats as compared to control animals. There was a significant decrease in p53, intracellular calcium and ROS generation on pretreatment with either celecoxib, fish oil or combination dosage of celecoxib and fish oil in DMBA treated animals with respect to only DMBA treated animals (group 2) with a comparatively marked alteration in combination dose regimen. However, an increase in MMP was observed in fish oil and the combination dosage regimen with respect to DMBA treated animals. Fish oil treatment in comparison to celecoxib in DMBA treated animals led to a significant increase in calcium, ROS and MMP levels. To conclude a synergistic effect of celecoxib and fish oil was observed in intracellular calcium, ROS and p53 levels in DMBA treated animals which may be responsible for the better chemopreventive efficacy of the combinatorial regimen. Citation Information: Cancer Prev Res 2010;3(12 Suppl):A37.