HMG-CoA Reductase and Polyamine Inhibitors for Prevention of Colorectal Cancer

描述（由申请方提供）：本提案的总体目标是开发有效的化学预防策略，并了解他汀类药物（3-羟基-3-甲基戊二酰辅酶A还原酶（HMG-R）抑制剂）和多胺抑制剂DFMO联合治疗结肠癌抑制结肠肿瘤的分子机制。结直肠癌是美国男性和女性最常见的恶性肿瘤之一。在开发翻译策略时，优选的方法是靶向选择性地有助于肿瘤生长的多个信号传导途径，使得其提供协同/累加功效。结肠肿瘤细胞通过激活鸟氨酸脱羧酶（ODC）内源性产生高水平的多胺。DFMO选择性抑制ODC活性，从而抑制内源性多胺合成和结肠肿瘤生长。对肿瘤细胞中多胺通过小窝蛋白-1（cav-1）和SLC 3A 2介导的途径转运的新见解表明，需要新的方法来有效地调节肿瘤细胞中的多胺。尽管DFMO抑制内源性多胺合成，但肿瘤细胞仍然可以通过依赖于cav-1的内吞机制摄取细胞外多胺。此外，Cav-1在一氧化氮（NO）的产生以及AKT和Rho信号传导的活化中起重要作用，导致增强的肿瘤细胞增殖和侵袭。我们的初步结果表明，瑞舒伐他汀与低剂量DFMO的组合抑制氧化偶氮甲烷（AOM）诱导的结肠异常隐窝病灶（ACF）和异常隐窝细胞增殖。我们的体外和体内研究结果表明，cav-1在结肠癌中起着重要作用，他汀类药物通过调节cav-1部分抑制结肠癌。因此，我们希望开发他汀类药物和DFMO的组合用于结肠癌的预防/治疗，并了解cav-1在结肠癌中的作用及其可能的miRNA调控。具体目的是1）确定瑞舒伐他汀（Crestor）在F344大鼠结肠癌发生模型中的体内疗效（最大耐受/最佳剂量选择;剂量反应效应;以及促进/进展阶段（早期/晚期干预）期间的有效性）。2)确定阿托伐他汀/瑞舒伐他汀和DFMO对大鼠结肠ACF（起始后/早期）或腺瘤（进展/晚期）进展为结肠腺癌形成的联合疗效。我们还想确定他汀类药物和DFMO对结肠粘膜和肿瘤组织中cav-1、多胺、ODC活性、NO（iNOS和eNOS活性）、SLC 3A 2、AKT和Rho信号传导蛋白、miRNA修饰水平的影响，并将这些结果与结肠肿瘤抑制相关联。3)使用cav-1-/-敲除小鼠模型确定cav-1在结肠癌发生中的作用，并确定有或没有DFMO的他汀类药物对cav- 1-/-和cav-1+/+小鼠中致癌物诱导的结肠肿瘤形成的影响。此外，拟议的研究将阐明选择性miRNA对结肠癌细胞中cav-1调控的作用，并评估他汀类药物和DFMO对cav-1 miRNA调控的可能调节作用。 公共卫生相关性：结直肠癌是美国男性和女性中最常见的恶性肿瘤之一，每年有50，000人死亡。开发翻译策略来预防结肠肿瘤生长的恶性进展是一种理想的方法。拟议的研究将产生详细的临床前评估，从而为他汀类药物单独或与低剂量ODC抑制剂联合用于结肠癌预防和治疗的最终临床评估奠定基础。此外，这些研究还将提供关于最广泛使用的他汀类药物瑞舒伐他汀的有价值信息，当在结肠癌发生的腺瘤阶段专门给药时，瑞舒伐他汀在人体中发挥多种健康益处，特别是用于结肠癌预防。此外，所提出的研究将提供关于他汀类药物和ODC抑制剂的组合如何提供增强的细胞多胺水平抑制从而导致协同结肠肿瘤生长抑制的机制见解，并最终阐明cav-1在结肠癌/预防中的作用。

DESCRIPTION (provided by applicant): The overall goal of this proposal is to develop effective chemopreventive strategies and understand the molecular mechanism of colon tumor inhibition by a combination of statins (3- hydroxy-3methyl glutaryl CoA reductase (HMG-R) inhibitors) and polyamine inhibitor, DFMO against colon cancer. Colorectal cancer is one of the most common malignancies in both men and women in the US. In developing translational strategies, a preferable approach is to target multiple signaling pathways that selectively contribute towards tumor growth, so that it provides a synergistic/additive efficacy. Colon tumor cells produce high levels of polyamines endogenously through the activation of ornithine decarboxylase (ODC). DFMO selectively inhibits ODC activity and thereby endogenous polyamine synthesis and colon tumor growth. New insights into the transport of polyamines in tumor cells by caveolin-1 (cav-1) and SLC3A2 mediated pathways suggest that new approaches are needed for effective polyamine regulation in tumor cells. In spite of the fact that DFMO inhibits endogenous polyamine synthesis, tumor cells can still uptake extracellular polyamines through a cav-1 dependent endocytic mechanism. Further, Cav-1 plays an important role in the generation of nitric oxide (NO) and activation of AKT and Rho-signaling, leading to enhanced tumor cell proliferation and invasion. Our preliminary results suggest, that a combination of rosuvastatin with low-dose DFMO suppresses azoxymethane (AOM)-induced colonic aberrant crypt foci (ACF), and aberrant crypt cell proliferation. Our in vitro and in vivo results suggest that cav-1 plays an important role in colon cancer, and statins exhibit colon tumor inhibition in part by modulating cav-1. Therefore, we want to develop a combination of statin and DFMO for colon cancer prevention/treatment and understand the role of cav-1 in colon cancer and its possible regulation by miRNAs. Specific aims are 1) Determine the in vivo efficacy of Rosuvastatin (Crestor) in a F344 rat colon carcinogenesis model (maximum tolerated/optimal dose selection; dose- response effects; and effectiveness during promotion/progression stages (early/late interventions). 2) Determine the combinational efficacy of atorvastatin/rosuvastatin and DFMO on the progression of colonic ACF (post-initiation/early stage) or adenoma (progression/late stage) to colon adenocarcinoma formation in rats. We also want to determine the effect of statins and DFMO on the levels of cav-1, polyamines, ODC activity, NO (iNOS and eNOS activities), SLC3A2, AKT and Rho signaling proteins, miRNA modifications in colonic mucosa and tumor tissues and correlate these results with colon tumor inhibition. 3) Define the role of cav-1 in colon carcinogenesis using cav-1-/- knockout mouse model and determine the effect of statins with or without DFMO on carcinogen induced colon tumor formation in cav- 1-/- and cav-1+/+ mice. In addition, proposed research will elucidate the role of selective miRNAs on the regulation of cav-1 in colon cancer cells, and assess the possible modulatory role of statins and DFMO on cav-1 miRNA regulation. PUBLIC HEALTH RELEVANCE: Colorectal cancer is one of the most common malignancies in both men and women in the US accounting for 50,000 deaths annually. Developing translational strategies to prevent the malignant progression of colon tumor growth is an ideal approach. The proposed studies will produce a detailed preclinical evaluation, thus setting the stage for the eventual clinical assessment of statins either alone or in combination with low-dose ODC inhibitor for colon cancer prevention and treatment. In addition, these studies will also provide valuable information on the most widely used statin, rosuvastatin which exerts multiple health benefits in humans and especially for colon cancer prevention, when it is specifically administered during the adenoma stage of colon carcinogenesis. Furthermore, the proposed studies will provide mechanistic insight into how a combination of statins and ODC inhibitors provides enhanced suppression of cellular polyamine levels leading to synergistic colon tumor growth inhibition and finally elucidate the role of cav-1 in colon cancer/prevention.