Reddy Bandaru S
Division of Nutritional Carcinogenesis, Institute for Cancer Prevention, Valhalla, New York, NY 10595, USA.
Environ Mol Mutagen. 2004;44(1):26-35. doi: 10.1002/em.20026.
During recent years, multidisciplinary studies in epidemiology and molecular biology have contributed to our understanding of the etiology of colorectal cancer; more importantly they have enabled us to approach its prevention. An impressive body of epidemiological data suggests an inverse relationship between colorectal cancer risk and consumption of diets rich in omega (omega)-3 fatty acids (n-3 PUFAs) or the regular use of nonsteroidal antiinflammatory drugs (NSAIDs), including aspirin. The development of strategies for the chemoprevention of colorectal cancer have been facilitated by the use of relevant animal models mimicking the neoplastic processes that occur in humans, including similarities in histopathology and molecular and genetic lesions during both the early and promotion/progression stages of carcinogenesis. Studies with the azoxymethane-F344 rat model indicate that diets rich in n-3 PUFAs, NSAIDs, selective cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS) inhibitors, and curcumin can reduce the incidence of colon cancer. Advances in the knowledge of the mechanisms by which chemopreventive agents act offer opportunities to use combinations of specific chemopreventive agents, having clinically beneficial aggregate activity with minimal toxicity. This approach is extremely important when a promising chemopreventive agent demonstrates apparent efficacy but may produce toxic effects at high doses. Our studies show that a combination of very low doses of piroxicam (NSAID) and difluoromethylornithine, a specific inhibitor of ornithine decarboxylase, or very low doses of COX-2 and HMG-CoA reductase inhibitors are more effective in inhibiting colon carcinogenesis than administration of these compounds as single agents even at higher levels. The natural history of colorectal cancer, from dysplastic aberrant crypts to adenomas and adenocarcinomas, offers multiple opportunities for assessment and intervention. Of further importance is to identify whether the molecular targets that are critical in the growth and survival of the malignant colorectal cell are modulated by n-3 PUFAs, NSAIDs, or COX-2 and iNOS inhibitors.
近年来,流行病学和分子生物学的多学科研究有助于我们理解结直肠癌的病因;更重要的是,它们使我们能够着手预防结直肠癌。大量令人印象深刻的流行病学数据表明,结直肠癌风险与富含ω-3脂肪酸(n-3多不饱和脂肪酸)的饮食摄入或定期使用包括阿司匹林在内的非甾体抗炎药(NSAIDs)之间呈负相关。通过使用模拟人类肿瘤形成过程的相关动物模型,包括在致癌作用的早期和促进/进展阶段组织病理学、分子和基因损伤方面的相似性,促进了结直肠癌化学预防策略的发展。用氧化偶氮甲烷-F344大鼠模型进行的研究表明,富含n-3多不饱和脂肪酸的饮食、NSAIDs、选择性环氧化酶-2(COX-2)、诱导型一氧化氮合酶(iNOS)抑制剂和姜黄素可降低结肠癌的发病率。化学预防剂作用机制知识的进展为使用具有临床有益总活性且毒性最小的特定化学预防剂组合提供了机会。当一种有前景的化学预防剂显示出明显疗效但高剂量时可能产生毒性作用时,这种方法极其重要。我们的研究表明,极低剂量的吡罗昔康(NSAID)与鸟氨酸脱羧酶的特异性抑制剂二氟甲基鸟氨酸联合使用,或极低剂量的COX-2和HMG-CoA还原酶抑制剂联合使用,在抑制结肠癌发生方面比单独使用这些化合物(即使剂量更高)更有效。结直肠癌从发育异常的隐窝到腺瘤和腺癌的自然病程提供了多个评估和干预机会。更重要的是确定恶性结直肠癌细胞生长和存活中关键的分子靶点是否受到n-3多不饱和脂肪酸、NSAIDs或COX-2和iNOS抑制剂的调节。
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