Mechanisms of action of ghrelin in muscle and adipose tissue in cancer-related ca

描述（由申请人提供）： 6.项目摘要/摘要每年，美国有超过150万人被诊断患有癌症。恶病质，定义为不自主的体重减轻> 5%，存在于高达80%的这些患者中，并且其包括肌肉和脂肪质量的损失。恶病质还导致功能表现、生活质量和存活率下降。然而，缺乏对这种情况的治疗。Ghrelin是一种主要由胃释放的新型激素，它刺激GH分泌，增加能量摄入，减少能量消耗。最近，它被假定具有抗炎作用。在我们的恶病质模型中，给予生长激素释放肽诱导瘦体重（LBM）和脂肪量增加。然而，其在这种情况下的作用机制尚未完全了解。这项研究的长期目标是确定生长素释放肽改善恶病质的程度，并建立在这种情况下调节生长素释放肽在肌肉和脂肪组织中作用的机制。我们的假设是，在癌症和顺铂诱导的恶病质的设置中，ghrelin将通过泛素-蛋白酶体途径下调蛋白水解来防止肌肉萎缩。这些变化将通过以下途径介导：a）能量摄入增加，B）胰岛素样生长因子-1（IGF-1）依赖性途径活化和c）核因子κ B（NF：B）依赖性炎症途径下调。我们还假设生长激素释放肽将通过减少脂肪分解和促进脂肪储存来防止脂肪损失。这些变化将通过以下途径介导：a）增加食物摄入，B）减少能量消耗和c）下调NF：B依赖性炎症途径。具体目标是：1）建立在顺铂诱导的恶病质环境中介导生长素释放肽诱导的肌肉保存的机制; 2）确定在顺铂诱导的恶病质环境中生长素释放肽诱导的脂肪沉积所涉及的机制;和3）表征生长素释放肽在由刘易斯肺癌（LLC）细胞系诱导的恶病质肿瘤模型中的作用。研究设计和方法：在我们的顺铂诱导的恶病质的啮齿动物模型中，我们观察到ghrelin预防顺铂诱导的脂肪和肌肉萎缩。我们现在建议，以确定在这种情况下参与的机制，并进一步表征这些途径，通过使用不同的模型恶病质诱导的LLC细胞系。我们将确定内源性生长激素释放肽和生长激素释放肽受体GHSR-1a的作用，通过建立我们的模型，在生长激素释放肽和GHSR-1a敲除恶病质。我们将建立NF：B和炎症的作用，利用一个新的转基因小鼠系，已被改造为表达荧光素酶和绿色荧光蛋白的启动子控制下，含有NF：B共识结合位点。NF：B的作用将通过使用NF：B拮抗剂来证实。食物摄入调节控制脂肪和肌肉质量的途径的程度将通过进行配对喂养实验来确定。通过给予IGF-1和GH受体拮抗剂来测试GH/IGF-1活化对生长素释放肽作用的相对贡献。将通过间接量热法进行能量消耗测量。基于我们当前模型中产生的数据，我们还将检验相同机制涉及LLC肿瘤诱导的恶病质的设定的假设。总之，这些实验将确定在与癌症相关的脂肪和肌肉萎缩的情况下介导ghrelin保护作用的机制，解决临床需求并填补文献中的空白。 公共卫生相关性： 7.癌症将影响1/2的退伍军人和非自愿的体重减轻（也称为恶病质）导致的脂肪和肌肉质量的损失将影响这些患者的绝大多数。恶病质通常会降低功能，导致生活质量下降，对抗癌治疗反应不良和死亡率增加。目前还没有有效的方法来治疗恶病质。新的激素生长激素释放肽增加食欲和体重。该建议将确定其在恶病质背景下对肌肉和脂肪的作用效果和机制。这项建议产生的结果将有助于我们开发恶病质的治疗方法，提高生活质量。通过增加肌肉质量和功能，患者将耐受更有效的治疗。他们也将能够呆在家里更长的时间，减少住院的需要，降低医疗保健的成本。恶病质也是许多其他疾病的并发症，包括肺和心脏疾病和衰老，通过这项建议产生的知识也将有助于我们为这些疾病建立新的治疗方法。

DESCRIPTION (provided by applicant): 6. Project Summary/Abstract Every year, over 1.5 million individuals in the US are diagnosed with cancer. Cachexia, defined as an involuntary weight loss >5%, is present in up to 80% of these patients and it encompasses the loss of muscle and fat mass. Cachexia also contributes to a decrease in functional performance, quality of life and survival. However, treatments for this condition are lacking. Ghrelin, a novel hormone released primarily by the stomach stimulates GH secretion, increases energy intake and decreases energy expenditure. More recently it has been postulated to have anti-inflammatory actions. In our model of cachexia, administration of ghrelin induced an increase in lean body mass (LBM) and fat mass. However, its mechanisms of action in this setting are not fully understood. The long-term objective of this research is to determine the extent to which ghrelin improves cachexia and to establish the mechanisms mediating ghrelin's action in muscle and adipose tissue in this setting. Our hypotheses are that in the setting of cancer- and cisplatin-induced cachexia, ghrelin will prevent muscle wasting by downregulating proteolysis through the ubiquitin-proteasome pathway. These changes will be mediated through: a) increases in energy intake, b) activation of insulin-like growth factor-1 (IGF-1)-dependent pathways and c) downregulation of nuclear factor kappa B (NF:B)-dependent inflammatory pathways. We also hypothesize that ghrelin will prevent fat loss by decreasing lipolysis and by favoring fat storage. These changes will be mediated through: a) increasing food intake, b) decreasing energy expenditure and c) downregulating NF:B-dependent inflammatory pathways. The specific aims are to: 1) Establish the mechanisms mediating ghrelin-induced muscle preservation in the setting of cisplatin-induced cachexia; 2) Determine the mechanisms involved in ghrelin-induced fat deposition in the setting of cisplatin-induced cachexia; and 3) Characterize the effects of ghrelin in a tumor model of cachexia induced by the Lewis lung carcinoma (LLC) cell line. Research Design and Methods: In our rodent model of cisplatin-induced cachexia we have observed that ghrelin prevents cisplatin-induced fat and muscle atrophy. We are now proposing to determine the mechanisms involved in this setting and further characterize these pathways by using a different model of cachexia induced by LLC cell line. We will determine the role of endogenous ghrelin and the ghrelin receptor GHSR-1a by setting up our model of cachexia in ghrelin and GHSR1a knock-outs. We will establish the role of NF:B and inflammation by exploiting a new transgenic mouse line that has been engineered to express luciferase and green fluorescent protein under control of a promoter that contains NF:B consensus binding sites. The role of NF:B will be confirmed by using NF:B antagonists. The extent to which food intake regulates the pathways controlling fat and muscle mass will be established by performing pair-feeding experiments. The relative contribution of GH/IGF-1 activation to ghrelin's action will be tested by the administration of IGF-1 and GH receptor antagonists. Energy expenditure measurements will be performed by indirect calorimetry. Based on the data generated in our current model, we also will test the hypothesis that the same mechanisms are implicated in the setting of LLC tumor -induced cachexia. Taken together, these experiments will determine the mechanisms mediating ghrelin's protective effects in the setting of fat and muscle wasting related to cancer, addressing a clinical need and filling a void in the literature. PUBLIC HEALTH RELEVANCE: 7. PROJECT NARRATIVE Cancer will affect 1 in 2 veterans and involuntary weight loss (also known as cachexia) resulting from a loss of fat and muscle mass will affect the vast majority of these patients. Cachexia often reduces functionality leading to a decrease in quality of life, poor response to anti-cancer therapies and increased mortality. Currently there is no effective way to treat cachexia. The novel hormone ghrelin increases appetite and body weight. This proposal will determine its effects and mechanisms of action in muscle and fat in the setting of cachexia. The results generated by this proposal will help us to develop treatments for cachexia, improving quality of life. By increasing muscle mass and function, patients will tolerate more effective treatments. They also will be able to stay home longer, decreasing the need for hospitalizations and reducing the cost of healthcare. Cachexia is also a complication of many other conditions including lung and heart disease and aging, the knowledge generated through this proposal also will help us in establishing new therapies for these conditions.