HILPDA and lipid metabolism in colorectal cancer

描述(由申请人提供)：结直肠癌(CRC)是发病率和死亡率的主要原因，是具有良好特征的遗传异常的结果。然而，还有其他因素调节恶性进展和对治疗的反应。由于肿瘤血管缺陷和血流灌注不良，大量实体肿瘤含有缺氧区。低氧激活适应性基因表达程序，调节包括增殖、新陈代谢和转移在内的关键生物过程。在许多癌症类型中，缺氧及其相关特征的存在是一个不利的预后因素，目前正在开发克服缺氧或以缺氧生理为靶点的治疗策略。低氧诱导的脂滴相关蛋白(HILPDA)是一个应激诱导基因，编码一种定位于脂滴的蛋白质。HILPDA转录本在结直肠癌标本中高度表达，但该蛋白的功能重要性或与其他临床参数的关系尚不清楚。我们已经建立了一个基因工程小鼠模型，其中HILPDA基因被破坏，并被萤火虫荧光素酶基因取代。这种基因敲除/报告小鼠品系将用于研究结直肠肿瘤的发生。我们假设，HILPDA通过影响结肠上皮和基质细胞对致癌信号的反应，是恶性进展的积极调节器。此外，脂肪形成的体外模型将用于确定HILPDA蛋白的功能结构域。我们提出这些研究的目的有三个：1)我们将在体内研究HILPDA在两种结直肠癌小鼠模型中的作用：a)在偶氮甲烷和葡聚糖硫酸钠治疗诱导的炎症相关癌变中；b)在APC失活的背景下，将APC Min无意义等位基因培育到我们的菌株中。在这两个模型中，肿瘤的发病率和多发性将被动态测量，病变的频谱将被病理评估。2)HILPDA蛋白的表达将被证实为更具侵袭性疾病的生物标志物。3)我们还将在体外鉴定HILPDA功能结构域，以挽救KO细胞的成脂缺陷和脂滴缺陷。这些HILPDA结构域随后将在可移植肿瘤中进行功能测试。这些研究将确定HILPDA在结直肠癌恶性进展中的意义，并为HILPDA功能的机制分析提供试剂。

DESCRIPTION (provided by applicant): Colorectal cancer (CRC) is a major cause of morbidity and mortality and is the result of well characterized genetic aberrations. However, there are additional factors that modulate malignant progression and response to therapy. A large number of solid tumors contain areas of hypoxia as a result of defective tumor vasculature and poor perfusion. Hypoxia activates adaptive gene expression programs, regulating crucial biological processes including proliferation, metabolism, and metastasis. The presence of hypoxia and associated features is an adverse prognostic factor in a number of cancer types, and strategies are being developed to either overcome hypoxia or target hypoxic physiology therapeutically. Hypoxia-Inducible Lipid Droplet Associated Protein (HILPDA) is a stress-induced gene, encoding for a protein shown to localize to lipid droplets. HILPDA transcripts are highly expressed in CRC specimens but the protein's functional importance or its relation to other clinical parameters is not known. We have generated a genetically engineered mouse model where the HILPDA gene was disrupted and was replaced by the firefly Luciferase gene. This knockout/reporter mouse strain will be used to investigate colorectal oncogenesis. We hypothesize that HILPDA is a positive modulator of malignant progression by impacting colonic epithelial and stromal cell responses to oncogenic signals. Additionally, an in vitro model of adipogenesis will be used to identify HILPDA protein functional domains. We propose these investigations in 3 specific aims: 1) We will investigate the role of HILPDA in vivo in two murine models of CRC: a) in inflammation-associated carcinogenesis induced by treatment with Azoxymethane and Dextran Sodium Sulfate and b) in the context of APC inactivation by breeding the APC Min nonsense allele into our strain. Tumor incidence and multiplicity will be kinetically measured and the spectrum of lesions will be pathologically evaluated in both models. 2) Protein expression of HILPDA will be validated as a biomarker of more aggressive disease in human CRC specimens. 3) We will also identify HILPDA functional domains that can rescue the adipogenesis defects and deficiency of lipid droplets of KO cells in vitro. These HILPDA domains will then be functionally tested in transplantable tumors. These studies will determine the significance of HILPDA in CRC malignant progression and generate reagents for the mechanistic analysis of HILPDA function.