结直肠癌是常见的消化道恶性肿瘤，具有发病率高、死亡率高的特点。许多研究显示肥胖是结直肠癌的独立危险因子，而炎症可能是介导肥胖与癌症发生的重要因素。近年来n-3不饱和脂肪酸及其衍生的脂质介质的抗炎、促消退作用受到广泛关注。本课题组前期研究发现可内源性合成n-3不饱和脂肪酸的fat-1转基因小鼠、肥胖相关性肠癌受到明显抑制，为此我们提出“n-3不饱和脂肪酸可能通过抗炎、促消退抑制肥胖相关肠癌”的假说。目前为止，尚不清楚DHA与EPA何者抗炎作用强，更适于防治肥胖相关性肠癌。鉴于新近研究报道肥胖动物的脂肪组织炎症与DHA而非EPA不足有关，而DHA从人体内清除的速率曾被发现明显慢于EPA，我们认为在肥胖相关肠癌防治中DHA比EPA更具应用价值。为验证这些设想，本项目将通过细胞实验、动物实验以及人体试验，对比分析DHA、EPA的抑癌作用，为探索肥胖相关性肠癌的有效预防措施提供科学依据。

Colorectal cancer, a common malignant tumor in digestive tract, has high morbidity and mortality. There is a lot of evidence that obesity is an independent risk factor for colorectal cancer, while inflammation is reported to be the bridge between obesity and colorectal cancer. Our previous study demonstrated that the development of obesity-related colon cancer was inhibited in fat-1 transgenic mice with the capacity of endogenously synthesis of n-3 polyunsaturated fatty acids. We proposed the hypothesis that n-3 polyunsaturated fatty acids may function to block the occurance of obesity-related colorectal cancer through inhibiting inflammation and promoting resolution. However, it is unclear which is more potent between DHA and EPA in anti-inflammation,and more suitable for anti-colorectal cancer related to obesity. Inflammation in adipose tissue was recently reported to be associated with the inadequancy in DHA rather than EPA. More importantly, washout of DHA from human body was found to be markedly slower than EPA. We proposed that DHA intervention will be more available for control of obesity-related colon cancer than EPA . The project is aimed to compare the efficiency of DHA and EPA in inhibition of inflammation in colon and reduction of colon cancer to explore the effective measures to control obesity-related colorectal cancer.