FoxO signaling and skeletal muscle atrophy

项目概要/摘要 恶病质的特征是进行性骨骼肌和体重减轻， 癌症患者。由于这种肌肉质量的损失导致虚弱，对常规药物的耐受性降低。 治疗和死亡率增加，了解导致肌肉萎缩的机制对于治疗至关重要 开发治疗方法以改善癌症患者的生活质量并提高其存活率。出版并 来自我们实验室的未发表的数据已经确定叉头盒（Fox）O类蛋白FoxO 1是一种关键的 与癌症患者恶病质有关的肌肉萎缩调节因子。我们鉴定了转录 阻遏物FoxP 1，作为FoxO 1上调的靶基因，以响应增加的肿瘤负荷（TBu） 在恶病质癌症的肌肉中也增加 患者在初步的实验中，我们发现FoxP 1 a）可能作为一种有效的关键转录抑制因子 参与肌肉收缩和维持肌肉完整性的因子和基因，B）足以 诱导肌纤维萎缩和c）TBu诱导肌纤维萎缩所需，因此涉及FoxP 1 在恶病质表型中。因此，目标1和2将检验我们的基本假设，即FoxP 1是足够的 诱导肌肉超微结构恶化、分解代谢途径活化和肌肉萎缩， 并且其响应于TBu的上调是这些肿瘤诱导的肌肉病理所需的。 具体目标1：我们将确定FoxP 1的作用并研究其分子机制。 足以导致肌肉萎缩具体目标2：确立角色并调查 FoxO 1-FoxP 1-MEF 2c轴驱动癌症诱导的肌肉萎缩的机制。我们将测试 这些假设在恶病质的常规临床前小鼠模型以及恶病质的新小鼠模型中是有效的。 癌症恶病质，其中原发性切除肿瘤来自胰腺导管腺癌（PDAC）患者 被附着在免疫缺陷小鼠的胰腺上以创造小鼠化身。 具体目标3：确定骨骼肌转录组和蛋白质组的变化， 在癌症恶病质的进展过程中失去PDAC患者和他们的小鼠化身。我们的第三个目标 利用了我们广泛获取PDAC患者肌肉和肿瘤组织的机会。因此，我们提出一个 无偏方法鉴定PDAC肌肉中的转录组（通过RNA-seq）和蛋白质组（通过iTRAQ） 在恶病质进展期间，患者及其小鼠化身作为纵向 人类的研究。我们建议补充这些发现与肌肉组织学和超微结构。 我们预计，我们的目标1和2的发现将阐明消耗和虚弱的关键机制， 目标3中生成的数据将产生大量新知识，以指导未来的预 旨在预防或延缓人类条件下癌症诱导的恶病质的临床研究。

Project Summary/Abstract Cachexia is characterized by progressive skeletal muscle and body weight loss and affects up to 80% of cancer patients. Since this loss of muscle mass contributes to weakness, reduced tolerance to conventional treatments, and increased mortality, understanding the mechanisms that drive muscle wasting is critical to the development of treatments to improve quality of life and enhance survival of cancer patients. Published and unpublished data from our lab have identified the Forkhead Box (Fox) Class O protein, FoxO1, as a critical regulator of muscle wasting that is associated with cachexia in cancer patients. We identified the transcriptional repressor, FoxP1, as a target gene upregulated by FoxO1 in response to tumor burden (TBu) that is increased at time points which precede and parallel muscle wasting and is also increased in muscle of cachectic cancer patients. In preliminary experiments we found that FoxP1 a) may act as a potent repressor of key transcription factors and genes involved in muscle contraction and the maintenance of muscle integrity, b) is sufficient to induce muscle fiber atrophy and c) is required for muscle fiber atrophy induced by TBu, thus implicating FoxP1 in the cachectic phenotype. Aims 1 and 2 will therefore test our underlying hypothesis that FoxP1 is sufficient to induce deterioration of muscle ultrastructure, activation of catabolic pathways, and muscle atrophy and weakness and that its upregulation in response to TBu is required for these tumor-induced muscle pathologies. Specific Aim 1: We will establish the role and investigate the molecular mechanisms by which FoxP1 is sufficient to induce muscle wasting. Specific Aim 2: To establish the role and investigate the mechanisms by which a FoxO1-FoxP1-MEF2c axis drives cancer-induced muscle wasting. We will test these hypotheses in a conventional pre-clinical mouse model of cachexia as well as in a novel mouse model of cancer cachexia in which primary resected tumors from pancreatic ductal adenocarcinoma (PDAC) patients are attached to the pancreas of immunocompromised mice to create mouse avatars. Specific Aim 3: To identify changes in the skeletal muscle transcriptome and proteome of weight losing PDAC patients and their mouse avatars during the progression of cancer cachexia. Our third aim takes advantage of our wide access to muscle and tumor tissue from PDAC patients. We thus propose an unbiased approach to identify the transcriptome (via RNA-seq) and proteome (via iTRAQ) in muscle of PDAC patients as well as their mouse avatars during the progression of cachexia as a surrogate for longitudinal studies in humans. We propose to complement these findings with muscle histology and ultrastructure. We anticipate that our findings from Aims 1 and 2 will elucidate key mechanisms of wasting and weakness in response to TBu, while data generated in Aim 3 will generate a plethora of new knowledge to guide future pre- clinical and clinical studies aimed at preventing or retarding cancer-induced cachexia in the human condition.