| 题名 | Hepcidin-Ferroportin 信号通路的异常调节对肿瘤进展的影响机制 |
| 作者 | 郭文丽 |
| 学位类别 | 博士 |
| 答辩日期 | 2015-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 刘思金 |
| 关键词 | hepcidin，ferroportin，铁，肿瘤，转移，EMT,Hepcidin Ferroportin Iron Cancer Metastasis EMT |
| 其他题名 | The mechanism of deregulated hepcidin-ferroportin axis affecting cancer development |
| 学位专业 | 环境科学 |
| 中文摘要 | 铁作为机体必需的营养元素参与多种生命过程，其代谢平衡对于维护细胞正常功能和机体的健康至关重要。机体的铁代谢主要由 hepcidin-ferroportin(FPN)轴进行调控。本研究组前期的研究工作表明，多氯联苯和重金属（如镉）等能够干扰hepcidin-FPN轴的功能，改变机体的铁代谢循环，引发肿瘤细胞的铁供应增加，导致肿瘤生长加速。 流行病学调查和实验数据表明hepcidin-FPN信号通路的异常会增加肿瘤发生和肿瘤恶化的风险。但是，我们对 hepcidin-FPN信号通路异常的肿瘤学效应，特别是对于其中的分子机制缺乏深入了解，例如其对肿瘤转移和表皮细胞向间质细胞转化(EMT)的效应却并不清楚。本学位论文的主要研究目标是：(1)明确系统性 hepcidin对肿瘤进展的影响；(2)探明FPN在肿瘤转移中的作用及其机制；(3)筛选是否存在其它铁调节基因，在肿瘤转移过程发挥了调节作用。 为了更加直观地考察系统性 hepcidin对肿瘤进展的影响，我们从国外引进了hepcidin敲除小鼠，并以此小鼠为研究对象，建立肺癌模型，探讨 hepcidin在肿瘤进展过程中的作用。瘤荷实验的结果表明，与野生型 (WT)小鼠相比，肺癌细胞 LL/2到 hepcidin敲除小鼠肺部归巢的能力明显降低，同时肿瘤在其肺部的进展也受到抑制。这是本文的第一个创新点，直接证实了系统性的 hepcidin缺失抑制肺癌细胞归巢及其在肺部的进展。 作为目前唯一已知的铁输出蛋白，FPN抑制肿瘤生长的作用已被证实。但是，对于其在肿瘤转移过程中的研究却是空白。通过对临床样本的检测，我们发现伴随转移的原位瘤中 FPN水平明显降低，比未发生转移的原位瘤下调了近70%。由此我们推断 FPN在肿瘤转移过程中可能发挥了重要作用。为了探索FPN在肿瘤转移过程中的作用，我们构建了诱导型 FPN高表达细胞系。体外实验的结果表明，升高的 FPN可以在不引起细胞死亡的同时，降低细胞分裂的速度和克隆形成能力。体内实验证明 FPN高表达可以引起小鼠体内肿瘤生长延缓，减少肿瘤细胞向肺和肝脏的转移。这是本文的第二个创新点。在分子水平，我们确认了FPN高表达会影响 DNA合成，阻滞细胞周期。更重要的是，FPN高表达抑制了EMT过程，具体体现在大幅度降低了 EMT的关键指标，例如 Snail1，Twist1，ZEB2和 vimentin。此外，FPN高表达后乳酸的水平也发生了下降，表明糖酵解过程受到抑制。 另一方面，为了更好地研究在肿瘤转移过程中铁调控相关基因的作用，我们建立了小鼠乳腺癌的肺转移模型，并利用这一模型，筛选到了原位细胞系和肺转移细胞系。同时，我们对转移瘤与非转移瘤中铁调控相关基因的表达情况进行了筛选，初步锁定了一些基因，稍后会细致研究这些基因在肿瘤转移中的作用机制。 总结起来，我们的结果显著突出了 hepcidin-FPN信号通路在调节肿瘤生长和转移方面的重要作用，为理清肿瘤进展中这一通路的作用机制提供了新的证据。同时建立的小鼠乳腺癌原位和肺转移细胞系，为以后研究铁调控相关基因在肿瘤转移过程中的作用奠定了基础。 |
| 英文摘要 | As an essential nutrient, iron participates in a myriad of physiological processes.Its balance is vital to maintain regular functions of cells and physical health. The systemic iron homeostasis is primarily controlled by the hepcidin-ferroportin(FPN)axis. Our previous work has proved that environmental pollutants such as polychlorinated biphenyls(PCBs) and heave metals(cadmium) could distupt the hepcidin-FPN signaling, and alter the circulation of iron metablism, which facilitated tumor cell proliferation and growth. Epidemiological and experimental studies suggest that disordered hepcidin-ferroportin (FPN) signaling is associated with the increased risk of cancers.However, the effects of deregulated hepcidin-FPN signaling on tumor behaviors such as the potential effects on metastasis and epithelial to mesenchymal transition (EMT)have not been closely investigated. The aims of this dissertation are as follows: (1) to make it clear that the effects of circulating hepcidin on tumor progression; (2) to elucidate the role of FPN in tumor metastasis and the underlying mechanism; (3) to make sure whether there are other iron-regulatory genes invovled in the modulation of tumor metastasis. To better investigate the influence of systemic hepcidin on cancer progression,we imported the hepcidin knock-out mice and established a model of lewis lung cancer. LL/2 cells were injected into the lateral tail veins of hepcidin-/-and wildtype(WT) mice. The data showed that remarkably undermined seeding propensity and inhibited tumor progression of LL/2 lung cancer cells were characterized in hepcidin-/- mice, relative to WT mice. Our current study represented the first line of direct evidence identifying a crucial role of circulating hepcidin in promoting lungtumor cell homing and consequential development in lungs of mice. As the only known iron exporter in mammals, reduced FPN expression was verified to enforce tumor growth due to ineffective iron efflux, coupled to increased intracellular iron retention in tumor cells. But the insights into the impact of FPN on metastasis are still limited. We first looked into the difference of FPN expression level between primary tumors with metastases and primary tumors without metastases from breast cancer patients. The level of FPN mRNA expression was greatly reduced by more than 70% in breast tumors with nodal metastases, compared to tumors without nodal metastases. These results implied a crucial role of FPN in controlling tumor progression including metastasis. To recognize the role of FPN in tumor progression,we deliberately established a breast cancer cell line with inducible forced expression of FPN. With this cell line, we discovered that increased FPN expression reduced cell division and colony formation in vitro, without eliciting significant cell death.Analogously, FPN overexpression impeded tumor growth and metastases to lung and liver in mice. At the molecular level, FPN overexpression was identified to undermine DNA synthesis and cell cycle progression. Importantly, FPN overexpression inhibited EMT, as reflected by the great decrease of representative EMT markers, Snail1,Twist1, ZEB2 and vimentin. Additionally, there was also a reduction of lactate production in cells upon induction of FPN overexpression, suggesting the reduced glycolysis. On the other hand, we established a novel orthotopic model of breast cancer metastasis to lungs for better studying the roles of iron-regulatory genes in tumor metastasis, where primary tumor sublines and lung metastatic tumor sublines were selected. Meanwhile, we preliminarily picked up some genes by testing the levels of iron-regulatory genes in primary tumors and lung metastatic tumors. Further study will focus on the effects of these genes on metastasis. Together, our results highlighted a crucial role of the hepcidin-FPN signaling in modulating tumor growth and metastasis, providing new evidence to understand the contribution of this signaling in cancers. Meanwhile the establishment of mouse breast cancer sublines from primary tumors and lung metastatic tumors facilitated detailed investigation of the effects of iron-regulatory genes on tumor metastasis. |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/34324]  |
| 专题 | 生态环境研究中心_环境化学与生态毒理学国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 郭文丽. Hepcidin-Ferroportin 信号通路的异常调节对肿瘤进展的影响机制[D]. 北京. 中国科学院研究生院. 2015. |
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