2012-08-012024-05-13https://scholars.lib.ntu.edu.tw/handle/123456789/649308摘要：頭頸癌是世界上主要癌症之ㄧ，也是台灣男性致死率排名第四的癌症。在頭頸癌中，癌 細胞的侵襲性和轉移也導致了頭頸癌患者的死亡。因此，釐清轉移的分子機制以及發展新的抗轉移治療策 略，是治療晚期頭 頸癌最重要的課題 。 上皮 - 間 葉 轉化 (epithelial-mesenchymal transition；EMT)是起因於上皮細胞喪失有秩序排列的極性並轉 化為間葉細胞，目前被認為是癌症轉移的主要機制。上皮-間葉轉化可由不同的轉錄因 子引發，包括 Twist1，Snail，Slug，SIP1，Zeb1，以及 E47 等。然而，在癌症衍生轉移 的過程，不同 EMT 引發因子間的相互關係，目前相關的研究報導仍非常少。過去的研 究發現頭頸癌細胞缺氧時，會經由 HIF-1α 誘導 Twist1 的表現而促進的上皮-間葉轉化。 也發現在頭頸癌細胞中，Twist1 會經由活化幹細胞基因 Bmi1 的表現而引發上皮-間葉轉化和癌症幹細胞的產生，導致病患有較差的預後。最近有越來越多的研究顯示，微小 RNA (microRNA)在癌症的惡化和轉移扮演重要角色。因此，我們預備探討 microRNA 在 Twist1 引發的轉移之角色，以及 Twist1 和其他 EMT 引發因子間的交互關係。我們初 步的研究顯示，在 Twist1 過度表現的頭頸癌細胞株中，microRNA29 家族(包括 miR-29a， b，c)的表現都有增加的現象。此外，我們發現了 miR-29 可抑制 SIN3A 的表現，而 SIN3A 已被發現參與在另一個重要的 EMT 因子 Snail 的下游基因調控機制中。因此我們推論 Twist1 可能藉由微小 RNA 的機轉，與 Snail 發生交互作用。在本研究計畫中，首先我們 將深究 Twist1-miR29-SIN3A 的詳細分子機制。我們也將探討當 SIN3A 被 Twist1 引發之 miR-29 抑制時，Twist1 與 Snail 間的交互作用。我們進一步要研究在缺氧狀態下，Twist1 和 Snail 同時被活化時，是否可透過 Twist1-miR29-SIN3A 產生交互作用，以及其病理生 理意義。最後我們將以小鼠動物實驗和頭頸癌臨床標本，來確認我們在體外實驗發現機 制之臨床重要性。本計劃的研究結果，將對頭頸癌轉移分子機制之了解提供重要科學資 訊，並對未來發展頭頸癌抗轉移藥物治療有重要價值。<br> Abstract: Head and neck squamous cell carcinoma (HNSCC) is one of the leading causes of cancer deaths worldwide, and it ranks the fourth male cancer-related death in Taiwan. In HNSCC, invasiveness and metastasis of cancer cells contribute to the major cause of mortality; therefore, elucidation of the mechanism and development of new strategies against metastasis is the utmost importance in treating advanced HNSCC. Epithelial-mesenchymal transition (EMT) is a process by which epithelial cells lose their polarity and are converted to a mesenchymal phenotype, and recently is considered as the major mechanism for cancer metastasis. The initiation of EMT is hallmarked by suppression of the intercellular junctional protein E-cadherin by a variety of transcriptional factors, including Twist1, Snail, Slug, SIP1, Zeb1 and E47. However, during metastatic evolution, the interplay between different EMT inducers has been investigated limitedly. Previously study demonstrated that hypoxia induces EMT of HNSCC through induction of Twist1 expression. Additionally showed that Twist1 promotes EMT and tumor-initiating capability through upregulation of Bmi1, and co-expression Twist1 and Bmi1 predicts a worse prognosis of HNSCC cases. Accumulated evidence suggests that microRNAs play essential roles in cancer progression and metastasis. Therefore, we aim to investigate the role of microRNA in Twist1-mediated cancer metastasis, and the interplay between Twist1 and other EMT regulators. Our preliminary data showed that the expression of miR-29 family, including miR-29a, b, and c were increased in Twist1-overexpressing HNSCC cells. Furthermore, we discovered that SIN3A, a co-repressor of another EMT regulator Snail, is a target of miR-29s. We therefore speculate that Twist1 modifies the function of Snail through microRNA machinery. In this proposal, we will delineate the regulatory mechanism of the Twist1-miR29s-SIN3A axis. We will also investigate the molecular interplay between Twist1 and Snail through Twist1-miR29s-SIN3A signal pathway. Furthermore, we will elucidate the molecular basis and pathophysiologic significance of Twist1-Snail interaction under hypoxic environment. Finally, we will confirm the in vitro finding by in vivo animal study and HNSCC samples. These results will provide crucial information for understanding the molecular basis of HNSCC metastasis, and will be valuable for developing new therapeutic strategies against advanced HNSCC.