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/摘要美国每年有超过150万人被诊断出患有癌症。恶病质，被定义为非自愿的体重下降5%，在这些患者中高达80%存在，它包括肌肉和脂肪的减少。恶病质还会导致功能表现、生活质量和存活率的下降。然而，目前还缺乏针对这种情况的治疗方法。Ghrelin是一种主要由胃释放的新型激素，可刺激GH分泌，增加能量摄入，减少能量消耗。最近，它被认为具有消炎作用。在我们的恶病质模型中，服用Ghrelin会导致瘦体重(LBM)和脂肪质量增加。然而，它在这一背景下的作用机制并不完全清楚。这项研究的长期目标是确定Ghrelin改善恶病质的程度，并建立在这种情况下Ghrelin在肌肉和脂肪组织中的作用机制。我们的假设是，在癌症和顺铂诱导的恶病质的背景下，Ghrelin将通过泛素-蛋白酶体途径下调蛋白分解，从而防止肌肉萎缩。这些变化将通过：a)增加能量摄入，b)激活依赖胰岛素样生长因子-1(IGF-1)的途径，以及c)下调依赖核因子-kappaB(NF：B)的炎症途径。我们还假设，Ghrelin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：a)增加食物摄入量，b)减少能量消耗和c)下调依赖于NF：B的炎症通路。其具体目的是：1)在顺铂诱导恶病质的背景下，建立Ghrelin诱导的肌肉保存的机制；2)在顺铂诱导的恶病质背景下，确定Ghrelin诱导的脂肪沉积的机制；以及3)表征Ghrelin在Lewis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：在我们的顺铂诱导恶病质的啮齿动物模型中，我们观察到Ghrelin可以预防顺铂诱导的脂肪和肌肉萎缩。我们现在建议通过使用一种不同的LLC细胞株诱导的恶病质模型来确定这一设定中涉及的机制，并进一步表征这些途径。我们将通过建立我们的Ghrelin和GHSR1a基因敲除的恶病质模型来确定内源性Ghrelin和Ghrelin受体GHSR-1a的作用。我们将通过开发一种新的转基因小鼠株系来确定NF：B和炎症的作用，该转基因鼠系已经被设计成在含有NF：B共识结合位点的启动子的控制下表达荧光素酶和绿色荧光蛋白。核因子：B的作用将通过使用核因子：B拮抗剂来证实。食物摄入量在多大程度上调节控制脂肪和肌肉质量的途径，将通过进行配对喂养实验来确定。GH/IGF-1激活对Ghrelin作用的相对贡献将通过给予IGF-1和GH受体拮抗剂来检验。能源消耗的测量将通过间接量热法进行。基于我们目前模型中产生的数据，我们还将测试假设，即LLC肿瘤诱导恶病质的背景中涉及相同的机制。综上所述，这些实验将确定Ghrelin在与癌症相关的脂肪和肌肉萎缩中发挥保护作用的机制，解决临床需求并填补文献中的空白。 公共卫生相关性： 7.项目叙事癌症将影响2名退伍军人中的1名，由于脂肪和肌肉质量减少而导致的非自愿体重减轻(也称为恶病质)将影响这些患者中的绝大多数。恶病质通常会降低功能，导致生活质量下降，对抗癌治疗反应不佳，并增加死亡率。目前还没有治疗恶病质的有效方法。新型荷尔蒙Ghrelin可以增加食欲和体重。这项提议将确定其在肌肉和脂肪中的作用和在恶病质环境中的作用机制。这项提议产生的结果将有助于我们开发治疗恶病质的方法，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。他们还将能够在家中呆得更长时间，从而减少住院需求并降低医疗保健成本。恶病质也是许多其他疾病的并发症，包括肺病、心脏病和衰老，通过这项提案产生的知识也将帮助我们建立针对这些疾病的新疗法。

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.