Targeting Lipid Metabolism in Colorectal Cancer

项目摘要 转移是包括结直肠癌（CRC）在内的实体瘤死亡的主要原因。我们的长期目标是通过了解脂肪酸代谢的变化如何导致转移性疾病，开发更具选择性的治疗方案，以预防或减少CRC转移的发生。 脂肪酸合成酶（Fatty acid synthase，FATS-N）是一种脂质从头合成的关键酶，在结直肠癌中被显著上调和激活，其活性与预后不良、疾病复发和死亡的风险较高相关。我们将Festival确定为晚期CRC的潜在靶点，并表明这种酶的上调是支持CRC转移的关键机制。然而，转移的潜在机制和对Festival抑制的抗性的潜在机制尚不清楚。本申请提出了一个全面的研究计划，以研究通过脂质代谢调节CRC转移的新机制。我们的初步数据表明，从头脂肪酸合成的主要产品，棕榈酸酯，选择性地用于鞘脂合成。过表达的FXR选择性地调节SphK 1和SphK 2的活性，并增加鞘氨醇-1-磷酸（S1 P）的水平，一种生物活性鞘脂参与转移。因此，在目标1中，我们将检验FXR通过上调SphK/S1 P轴增强转移的假设，并且我们将确定SphK 1和SphK 2对CRC转移的贡献。此外，我们的初步研究表明，表达之间的相关性？FRESINS和CD 36，脂肪酸转位酶负责外源性FA摄取。我们的数据显示，Festival的抑制导致CD 36的上调，并且它可能是目前正在II期临床试验中测试的新型Festival抑制剂的耐药性的潜在机制。因此，在目标2中，我们将阐明FXR如何调节CD 36，并确定CD 36上调有助于CRC转移的分子机制，包括CD 36上调对鞘脂代谢和S1 P合成的影响。在目标3中，我们将测试通过CD 36抑制FA摄取是否会增加新型FXR抑制剂TVB-3664在CRC中的功效。 我们将利用来自患者的生物样品，人类原代CRC细胞，从转基因小鼠和CRC转移模型中建立的肿瘤类器官，这些模型是临床前靶点和药物评估的最先进模型。这些模型将与最先进的方法结合使用，包括靶向和稳定的同位素分辨代谢组学（SIRM），以评估脂质合成和FA摄取改变对癌细胞代谢的影响。这些研究具有很高的转化影响，因为CD 36和FEV 1抑制剂目前在多项临床前研究和I-II期临床试验中进行了测试，迫切需要对其在CRC中的作用进行更多的研究和了解。除了验证FXR、SphKs和CD 36作为CRC中的治疗靶标之外，本申请中提出的代谢和信号传导途径的综合分析也具有鉴定CRC的新的可药物化靶标和治疗策略的潜力。

PROJECT SUMMARY Metastasis is the main cause of death from solid tumors including colorectal cancer (CRC). Our long-term goal is to develop more selective therapeutic options to prevent or reduce the incidence of CRC metastasis by understanding how changes in fatty acid metabolism contribute to metastatic disease. Fatty acid synthase (FASN), a key enzyme of de novo lipid synthesis, is significantly upregulated and activated in CRC, and its activity is associated with poor prognosis, higher risk of disease recurrence, and death. We identified FASN as a potential target for advanced CRC and showed that upregulation of this enzyme is a key mechanism supporting metastasis in CRC. However, the underlying mechanisms of FASN regulation of metastasis and potential mechanism of resistance to FASN inhibition are not understood. The current application proposes a comprehensive research plan to study novel mechanisms of regulation of CRC metastasis by lipid metabolism. Our preliminary data suggest that the primary product of de novo fatty acid synthesis, palmitate, is selectively used for sphingolipid synthesis. Overexpression of FASN selectively regulates activity of SphK1 and SphK2 and increases the level of sphingosine-1-phosphate (S1P), a bioactive sphingolipid implicated in metastasis. Therefore, in Aim 1, we will test the hypothesis that FASN enhances metastasis by upregulating the SphK/S1P axis and we will determine the contributions of SphK1 and SphK2 to CRC metastasis. Furthermore, our preliminary studies show a correlation between expression of FASN and CD36, a fatty acid translocase responsible for exogenous FA uptake. Our data show that inhibition of FASN leads to upregulation of CD36 and it can be a potential mechanism of resistance to novel FASN inhibitors that are currently being tested in Phase II clinical trials. Therefore, in Aim 2, we will elucidate how FASN regulates CD36 and determine molecular mechanisms by which upregulation of CD36 contributes to CRC metastasis including the effect of CD36 upregulation on sphingolipid metabolism and S1P synthesis. In Aim 3, we will test whether inhibition of FA uptake via CD36 will increase efficacy of a novel FASN inhibitor TVB-3664 in CRC. We will utilize biological samples from patients, human primary CRC cells, tumor organoids established from genetically modified mice and CRC metastasis models, which are the most advanced models for pre-clinical target and drug evaluations. These models will be used in conjunction with state-of-the-art approaches, including targeted and stable isotope-resolved metabolomics (SIRM), to evaluate the effect of alteration in lipid synthesis and FA uptake on cancer cell metabolism. These studies have a high translational impact since CD36 and FASN inhibitors are currently tested in multiple pre-clinical studies and Phase I-II clinical trials and there is urgent need for more research and knowledge on their effects in CRC. Beside validation of FASN, SphKs and CD36 as therapeutic targets in CRC, the comprehensive analysis of metabolic and signaling pathways proposed in the current application also have the potential to identify new druggable targets and therapeutic strategies for CRC.