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標題: | 微核醣核酸在癌症血管新生與侵襲所扮演的角色 The role of microRNA in human cancer angiogenesis and invasion |
作者: | Shih-Ting Cha 查詩婷 |
指導教授: | 郭明良(Min-Liang Kuo) |
關鍵字: | 微核醣核酸,癌症,腫瘤血管新生, MicroRNA,Cancer,tumor angiogenesis, |
出版年 : | 2010 |
學位: | 博士 |
摘要: | 中文摘要
癌症為當今世上最常見的致死疾病之一,而癌轉移則是導致癌症病患死亡的主因。微核醣核酸(microRNA)是新發現的一種不會轉譯成蛋白質的小分子核醣核酸,它可扮演內源性的核醣核酸干擾(RNA interference),透過轉錄後調控機制,調控其標的基因的表現;並可能扮演腫瘤抑制基因或致癌基因的功能。微核醣核酸的異常表現在影響癌症轉移能力與預後上或許扮演著重要的角色。在本篇論文中,我們分別討論microRNA-519c和microRNA-211在腫瘤血管新生與侵襲所扮演的角色並定義為腫瘤抑制微核醣核酸。在本論文的第二章節,我們藉由報導基因表現分析(Reporter assay)確定miR-519c為缺氧誘導分子-1α (HIF-1α)的直接調控者;藉由直接作用於 HIF -1α的3'UTR,抑制缺氧誘導分子-1α蛋白生成而降低腫瘤的血管生成。大規模分析135位肺癌患者miR - 519c表現,發現過度表達miR - 519c之患者其預後較好,因此miR - 519c可做為預測肺癌病患預後與轉移的生物標記。在小鼠腫瘤生成性實驗中也發現,以人為外送的方法讓癌細胞過度表現miR - 519c並將細胞注入小鼠皮下除了可顯著抑制小鼠腫瘤血管新生,對腫瘤生成速度和轉移至其它器官的能力亦有顯著抑制效果。此外,我們發現肝細胞生長因子(hepatocyte growth factor, HGF)可藉由Akt-dependent pathway 抑制mature-miR - 519c maturation。在微核醣核酸的生合成機制(microRNA biogenesis)中提供另一有趣的結果。 在本論文的第三章節,我們利用黑色素細胞癌模式進行微核醣核酸在細胞侵襲所扮演的角色。黑色素細胞癌是最惡性的皮膚腫瘤,它極易轉移,且對大部分的現有化學治療藥物具有抗藥性。有越來越多的證據顯示miRNA的表現在人類癌症中出現異常,最近研究也發現miRNA與黑色素細胞癌的發生與進展有關。由於目前對於轉移的黑色素細胞癌並無有效的治療方法,找出新的分子機制或預後標記,將可以促成開發針對轉移黑色素細胞癌的新療法。在先前的初步研究中,我們選取了六位黑色素細胞癌病患的轉移部位組織與原發部位進行同一個人間的比較,運用miRNA 基因微陣列分析,找到5個miRNAs (miR-211, miR-107, miR-141, miR-187 and miR-514) 在6對檢體中均有一致性的下降。其中,miR-211 的相對表現量與黑色素細胞癌細胞株的移動力與侵襲力呈反相關;體外實驗也顯示miR-211可能藉由抑制黑色素細胞癌的移動與侵襲而調控其轉移。希望藉由此研究確認miR-211在黑色素細胞癌轉移所扮演的角色與其分子機制,並可望開發未來診斷與治療的新方向。 英文摘要 MicroRNAs (miRNAs) are a new class of endogenous, small evolutionarily conserved non-coding RNAs of 18-25 nucleotides in length that act as post-transcriptional repressors of gene expression involved in fundamental cell processes, such as development, differentiation, proliferation, survival and death ranging from plants to human. A wide spread role for miRNAs in diverse molecular processes driving the initiation and progression of various tumor types has recently been described. Here, we discuss the role of mir-519c and mir-211 in tumor angiogenesis and invasion/ migration, which define as tumor suppressor. In first chapter of this thesis, we have identified miR-519c as a hypoxia independent regulator of HIF-1α, acting through direct binding to HIF-1α 3’UTR and leading to reduced tumor angiogenesis. In consistence with the over-expression of miR-519c in cancer patients with better prognosis, mice injected with miR-519c over-expressing cells exhibited dramatically reduced HIF-1α level, followed by suppressed tumor angiogenesis, growth, and metastasis. In addition, we found that hepatocyte growth factor (HGF), a known HIF-1α inducer, reduced the miR-519c levels through an Akt-dependent pathway. This regulation was post-transcriptional and may be mediated by suppression of miR-519c maturation. Taken together, our findings provide the first evidence that miR-519c is a pivotal regulator of tumor angiogenesis and, moreover, micro environmental HGF contributes to regulating miR-519c biogenesis in cancer cells. In addition, we also found a significant down-regulate 5 miRNAs (miR-211, miR-107, miR-141, miR-187 and miR-514) in metastatic melanomas comparing 6 pairs of metastatic and primary melanomas from six patients. Further results suggested that miR-211 could regulate melanoma metastasis by inhibiting migration/invasion abilities of melanoma cells. Specifically, compared with expression levels in melanocytes, levels of miR-211 were consistently reduced in all eight non-pigmented melanoma cell lines we examined; they were also reduced in 21 out of 30 distinct melanoma samples from patients, classified as primary in situ, regional metastatic, distant metastatic, and nodal metastatic. Transfection of anti-miR-211 oligonucleotides (200 pmole) enhances the migration and invasion abilities of MeWo and B16F0 cells. In vivo model shows that over-expression of miR-211 in A375 melanoma cells attenuates its lymph node metastatic ability (n=12 for each group; lymph node meta rate: A3-211 vs. A3-VEC= 3/12 vs. 12/12). The aim of this study is to investigate the roles and molecular mechanisms of miR-211 in melanoma metastasis, which may improve the development of prognostic markers and novel treatments for melanoma. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/48568 |
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