COX-2 Inhibitor and N-3PUFA in Colon Cancer Prevention

描述（由申请人提供）：我们研究的长期目标是确定结肠癌预防的创新策略，并将临床前疗效研究的知识应用于结肠癌高风险个体作为预防手段。目前的证据表明，富含n-3多不饱和脂肪酸（n-3 PUFA）和环氧合酶（考克斯）-2抑制剂（如塞来昔布）的饮食可抑制氧化偶氮甲烷（AOM）诱导的F344大鼠结肠癌发生。尽管考克斯-2抑制剂对结肠肿瘤的抑制作用比传统的NSAID有效得多，但高剂量的考克斯-2抑制剂在人体中引起了一些副作用。本申请中提出的临床前实验将提供令人信服的证据，即富含n-3 PUFA的饮食与考克斯-2抑制剂塞来昔布组合的聚集作用将是显著的，而由考克斯-2抑制剂诱导的副作用将最小化。拟议的研究将评估两个假设：a）考克斯-2抑制剂和n-3 PUFA的作用机制存在协同作用，前者通过调节类二十烷酸的产生、血管生成和细胞凋亡来抑制致癌作用，而后者通过NO途径、细胞分化和细胞凋亡来抑制结肠致癌作用，B）富含n-3 PUFA的饮食与考克斯-2抑制剂的组合将通过协同调节上述分子参数来增加功效。具体目标是：1）确定在富含n-3 PUFA的饮食中施用低剂量塞来昔布与在含有混合脂质的高脂肪西式饮食中施用高剂量塞来昔布相比在AOM诱导的F344大鼠结肠癌发生中的功效。2)确定塞来昔布在富含n-3 PUFA的饮食中给药对大鼠结肠粘膜和肿瘤中结肠癌相关基因的联合作用。我们将重点关注凋亡基因，Bcl-2，NF？B和类花生酸和NO途径，包括考克斯-2，LOX，和iNOS及其相互作用与其他功能组的基因在结肠癌的发生，使用DNA微阵列，RT-PCR和Western印迹分析。在临床前模型中明确描述协同效应将允许合理设计人体临床试验。

DESCRIPTION (provided by applicant): The long-term objective of our research is to identify innovative strategies for colon cancer prevention and to apply the knowledge from preclinical efficacy studies to use with individuals at high-risk for colon cancer as a means of prevention. Current evidence suggests that a diet rich in n-3 polyunsaturated fatty acids (n-3 PUFAs) and cyclooxygenase (COX)-2 inhibitors, such as celecoxib suppress azoxymethane (AOM)-induced colon carcinogenesis in F344 rats. Although colon tumor inhibition by COX-2 inhibitors is much more effective than traditional NSAIDs, high doses of COX-2 inhibitors have caused some side effects in humans. The preclinical experiments proposed in this application will provide compelling evidence that the aggregate action of n-3 PUFA-rich diet in combination with a COX-2 inhibitor, celecoxib would be significant, while side effects induced by the COX-2 inhibitor would be minimized. The proposed studies will evaluate two hypothesis: a) There is synergism in the mechanisms of action of COX-2 inhibitors and n-3 PUFAs, the former inhibiting carcinogenesis through modulation of generation of eicosanoids, angiogenesis and apoptosis while the latter suppressing colon carcinogenesis through NO pathways, cell differentiation and apoptosis, b) the combination of a diet rich in n-3 PUFAs with a COX-2 inhibitor will increase the efficacy by modulating synergistically the above molecular parameters. The specific aims are: 1) Determine the efficacy of a low dose of celecoxib administered in n-3 PUFA rich diet as compared when a high dose of this agent administered in a high-fat, Western style diet containing mixed lipids in AOM-induced colon carcinogenesis in F344 rats. 2) Determine the combined effects of celecoxib administered in n-3 PUFA-rich diet on colon cancer-related genes in colonic mucosa and tumors of rats. We will focus on apoptotic genes, Bcl-2, NF?B and on the eicosanoid- and NO-pathways including COX-2, LOX, and iNOS and their interactions with other functional groups of genes in colon carcinogenesis using DNA microarrays, RT-PCR and Western Blot analysis. Clear delineation of the synergistic effects in preclinical models will allow the rational design of human clinical trials.