结直肠癌是严重威胁人群健康的重要疾病，我们前期研究发现，n-3多不饱和脂肪酸（n-3PUFAs）摄入量高可降低结直肠癌的发病风险，但其与结直肠癌预后的关系及其作用机制目前尚不清楚。我们以上皮间质转化（EMT）这一结直肠癌侵袭转移中的关键事件为切入点，研究n-3PUFAs对结直肠癌转移和预后的影响及机制。首先利用已建立的包括2500例结直肠癌病人的队列人群进行前瞻性研究，首次深入分析中国人群中膳食和体内n-3PUFAs与结直肠癌预后的关系。然后在结肠癌裸鼠原位移植瘤模型中，阐明n-3PUFAs对肿瘤生长转移的抑制作用及机制。在此基础上，采用结肠癌细胞模型，在体外深入探讨n-3PUFAs活化PPARγ阻断TGF-β/Smad信号通路、抑制EMT和结直肠癌侵袭转移的作用机制。本研究将从营养新角度阐明n-3PUFAs抑制结直肠癌侵袭转移的分子机制，为探索适合结直肠癌病人的营养干预措施提供科学依据。

Colorectal cancer is an important disease that seriously threatens people’s health. Our previous studies showed that higher intake of n-3 polyunsaturated fatty acids (n-3 PUFAs) reduced the risk of colorectal cancer. However, the relationship between n-3 PUFAs and the prognosis of colorectal cancer and its mechanism are still unclear. Starting from the key event of epithelial-mesenchymal transition (EMT) in invasion and metastasis of colorectal cancer, we explored the effect of n-3 PUFAs on metastasis and prognosis of colorectal cancer and its molecular mechanism. Firstly, a cohort including 2500 colorectal cancer patients were followed-up. The association between n-3 PUFAs and the prognosis of colorectal cancer was explored for the first time in Chinese populations. Then, in the orthotopic transplantation model of colon cancer in nude mice, we clarified whether n-3PUFAs can inhibit the growth and metastasis of colon cancer and its mechanism. On this basis, we used the colon cancer cell model to investigate in vitro whether n-3PUFAs could slow down the invasion and metastasis of colorectal cancer by activating PPAR gamma, blocking TGF-β/Smad signaling pathway and reducing EMT of colon cancer cells. This study will clarify the role of n-3 PUFAs in slowing down the invasion and metastasis of colorectal cancer and its molecular mechanism from the perspective of nutritional metabolism. It will also provide scientific evidence for establishing nutritional intervention measures for colorectal cancer patients.