Variations of calorie restriction for the prevention of pancreatic cancer

描述（由申请人提供）：胰腺癌的进展需要很多年，这为早期发现和预防提供了机会。研究已经确定身体质量指数（BMI）升高是胰腺癌的一个危险因素。长期以来，在实验动物中，热量限制导致的体重下降与延长预期寿命和减少肿瘤发病率有关。长期和间歇性的热量限制对肿瘤的发展有强大的保护作用。这一建议提出了一个假设，即间歇性卡路里限制将通过改变选定的生物标志物来阻止肿瘤前病变的发展和延缓肿瘤病变的进展。喀斯特;Pdx-1Cre小鼠模型为研究侵袭前状态下预防策略的有效性提供了机会。具体目标是：1。确定间歇性热量限制/再喂养和慢性限制对K-ras肿瘤前病变向肿瘤病变发展的影响；Pdx-1Cre转基因小鼠相对于自由喂养小鼠。2. 通过测量：a)血清中IGF-1和IGFBP-3的浓度，b) K-ras胰腺中增殖和凋亡的程度，确定PanIn进展到晚期病变的每个阶段的生物标志物水平，以及慢性和间歇性卡路里限制是否会改变这些生物标志物；c)胰腺导管细胞中IGF-1和IGFBP-3蛋白水平，d)使用AQUA软件使用尖端基质组装组织阵列激活胰腺导管细胞中EGFR、Ras/MAPK和PI3K/Akt信号。从6周开始，小鼠将被分配到：第1组：自由喂养小鼠，第2组：间歇性限制热量/饲料小鼠，每2周以50%的自由热量摄取量喂养，然后进行2周的自由喂养；第三组：慢性热量限制组，按照间歇性热量限制小鼠的4周限制/再喂养间隔，饲喂平均日摄食量。在52周龄和64周龄时，我们将通过PET成像筛查所有小鼠是否存在肿瘤。在64周时，将处死第1阶段的小鼠，以评估PanIn病变和生物标志物。在16周龄和28周龄时处死2个亚组小鼠，通过组织阵列、增殖和血清IGF-1和IGFBP-3浓度测定胰腺中EGFR、Ras/MAPK、PI3K/Akt和mTOR活化以及IGF-1和IGFBP-3蛋白表达的进展变化。从这项研究中获得的数据将提供关于卡路里限制是否有利于预防胰腺癌和识别这种干预改变的生物标志物的第一个可用信息。公共卫生相关性：胰腺癌是一种致命的疾病，只有5%的患者寿命超过5年。这是一种没有已知的治疗方法或预防策略的疾病。因此，迫切需要找到预防这种疾病的方法。基于卡路里限制在预防多种癌症方面取得的成功，本研究将在相关小鼠模型中评估慢性和间歇性卡路里限制是否会通过针对癌前病变来预防胰腺癌。此外，本研究将确定与癌前病变发展相关的早期信号生物标志物，并确定慢性和间歇性卡路里限制是否会降低Ras/MAPK/PI3K的激活、胰腺的增殖、细胞凋亡和循环IGF-1。

DESCRIPTION (provided by applicant): Pancreatic cancer progresses over many years, which offers the opportunity for early detection and prevention. Studies have identified elevated body mass index (BMI) as a risk factor for pancreatic cancer. Lower body weights resulting from calorie restriction have long been associated with extended life expectancy and reduced tumor incidence in laboratory animals. Chronic and intermittent calorie restriction have a powerful protective effect against tumor development. This proposal addresses the hypothesis that intermittent calorie restriction will prevent the development and delay progression of preneoplastic to neoplastic lesions by altering select biomarkers. The Kras; Pdx-1Cre mouse model provides an opportunity to study the efficacy of prevention strategies during the preinvasive state. The specific aims are: 1. To determine the effects of intermittent caloric restriction/refeeding and chronic restriction on the developmental progression of preneoplastic to neoplastic lesions in the K-ras; Pdx-1Cre transgenic mice relative to ad libitum fed mice. 2. Determine biomarker levels during each stage of PanIn progression to advanced lesions and whether chronic and intermittent calorie restriction modifies these biomarkers by measuring: a) serum concentrations of IGF-1 and IGFBP-3, b) the extent of proliferation and apoptosis in the pancreases from K-ras; Pdx-1Cre transgenic mice, c) IGF-1 and IGFBP-3 protein levels in pancreatic ductal cells, and d) activation of EGFR, Ras/MAPK, and PI3K/Akt signaling in pancreatic ductal cells using the cutting edge matrix assembly tissue array with AQUA software. Starting at 6-weeks mice will be assigned to: Group 1: ad libitum fed mice, Group 2: intermittent calorie restricted/refed mice fed in 2-week intervals at 50% of the ad libitum caloric intake followed by 2 weeks of ad libitum feeding; and Group 3: Chronic calorie restricted pair fed the average daily food intake that corresponds to the 4-wk restriction/refeeding interval of the intermittent calorie restricted mice. At 52 and 64 weeks of age, we will screen all the mice for the presence of a tumor by PET imaging. At 64 weeks mice in aim 1 will be sacrificed for evaluation of PanIn lesions and biomarkers. For aim 2 subgroups of mice will be sacrificed at 16 and 28 weeks of age to determine progressive changes in activation of EGFR, Ras/MAPK, PI3K/Akt, and mTOR and protein expression of IGF-1 and IGFBP-3 in pancreas by tissue array, proliferation, and serum concentrations of IGF-1 and IGFBP-3. Data obtained from this study will provide the first available information on whether calorie restriction will be of benefit for preventing pancreatic cancer and identification of biomarkers altered by this intervention. PUBLIC HEALTH RELEVANCE: Pancreatic cancer is a deadly disease with only 5% of the patients living longer than 5 years. It is a disease with no known cure or strategy to prevent its occurrence. Thus, it is urgent to find ways to prevent this disease. Based upon the success of calorie restriction in preventing many types of cancer, this study will evaluate whether chronic and intermittent calorie restriction will prevent pancreatic cancer by targeting precancerous lesions in a relevant mouse model. Additionally, this study will identify early signaling biomarkers associated with precancerous lesion development and determine whether chronic and intermittent calorie restriction decreased the activation of Ras/MAPK/PI3K, proliferation, apoptosis in the pancreas, and circulating IGF-1.