利用The Cancer Genome Atlas (TCGA)肺癌組織資料庫研究微型核糖核酸-5臂端與-3臂端的選擇改變:微型核糖核酸-5p 與-3p可能扮演不同肺癌癌化角色

Use of TCGA Database To study the Arm Selection Preference of MicroRNA in Lung Cancer: miRNA-5p and -3p might Have Distinct Role in Lung Cancer

李美漁

肺癌 ； 微型核糖核酸 ； 生物資訊 ； 微型核糖核酸-324 ； 微型核糖核酸-335 ； lung cancer ； microRNA ； bioinformatics ； arm switch ； miR-324 ； miR-335

義守大學生物科技學系學位論文

2017年

碩士

劉麗芬

繁體中文

在台灣肺癌一直高居所有癌症發生率前幾名，每年因肺癌而死亡的人數高居不下，在臨床上肺癌晚期轉移是導致癒後不良最主要的原因之一，因此尋找一個有效的早期診斷生物標記將有助於提升肺癌病患存活率。人體內存在大量微型核糖核酸，而這些微型核糖核酸已經被證實在癌症的發展過程扮演重要的角色，先前的研究發現微型核糖核酸的-5臂與-3臂選擇性調控，在癌症細胞中同樣扮演重要角色，藉由這種-5臂與-3臂的選擇性調控，可以增加微型核糖核酸的功能上多樣性與複雜度，然而截至目前為止，在肺癌中微型核糖核酸-5臂與-3臂的選擇性調控仍然未被深入探討，因此本論文我們從The Cancer Genome Atlas( TCGA)下載了肺癌以及癌旁正常組織的微型核糖核酸表現圖譜，我們的結果顯示在肺癌中組織中，大部份的微型核糖核酸-5臂與-3臂比例在肺癌與正常肺泡細胞中維持一定，然而有一小部份的微型核糖核酸-5臂以及-3臂表現在肺癌的發展過程中會發生改變，我們稱之為微型核糖核酸arm switch，我們的結果發現,總共有36個微型核糖核酸arm switch顯著性增加；而有19個微型核糖核酸顯著性減少，然而arm switch的機制目前並不清楚，需要更多的研究來釐清。在本論文中我們選擇二個會發生arm switch的微型核糖核酸(miR-324以及miR-335)進一步探討其-5臂與-3臂在肺癌細胞中的生物功能，我們的結果發現，miR-324-5p與miR-324-3p兩者均顯著性在肺癌中高度表現，在肺癌細胞株中大量表現miR-324-5p會促進肺癌細胞的生長與侵犯的能力，而大量表現miR-324-3p僅會促進肺癌細胞生長但對於侵犯能力上沒有顯著的影響；miR-335-5p在肺癌組織中呈現顯著性低度表現，大量表現miR-335-5p發現可以顯著性抑制肺癌細胞生長與轉移的能力，而miR-335-3p反而是在肺癌組織中呈現顯著性高表現，並且表現miR-335-3p可以增加肺癌細胞的生長能力。綜合以上的結果顯示，某些微型核糖核酸在肺癌中會有arm switch的現象，而-5臂與-3臂的選擇調控可能是一個複雜且新穎調控微型核糖核酸的機制，這些發現提供未來治療肺癌一個嶄新方向。

Lung cancer is the most common cancer in Taiwan. A major cause of the lethality of lung cancer is distant metastases at advance stage, which usually leading to poor survival rate. Therefore, investigating and improving diagnostic sensitivity of biomarkers for early stage tumors is beneficial for improving the survival rate of lung cancer patients. MicroRNA (miRNA) dysfunction, a critical hallmark of lung cancer, leads to tumor suppressive and oncogenic gene disorder during lung cancer progression. The selection of the 5p and 3p arms of miRNA is a mechanism that improves the modulation of the biological function diversity of miRNA and complicates its regulatory network in human cancers. Here, we used The Cancer Genome Atlas (TCGA) database to study the arm selection preference of miRNA in lung cancer and corresponding adjacent normal tissue. We found that 5p and 3p arm selection is consistent in most miRNAs in lung cancer. Only a few miRNAs showed significant changes in the arm selection preference in lung cancer. Our data revealed that the arm selection preference of 36 miRNAs significantly increased, whereas that of 19 miRNAs decreased in lung cancer compared with corresponding adjacent normal tissues. Among them, the biological function of the individual arm of miR-324, miR-335 and miR-455 were selected for further investigating in this study. Our data showed that both miR-324-5p and -3p were significantly overexpressed in lung cancer cells. Ectopic expression of miR-324-5p promoted the cell proliferation and invasion ability, whereas miR-324-3p overexpression increased the cell proliferation but did not influence the invasion ability of the cancer cells. The expression levels of miR-355-5p significantly decreased in lung cancer and played tumor suppressive role in silencing cancer cell growth and invasion ability. Otherwise, the miR-355-3p overexpressed in lung cancer and promoted lung cancer cell proliferation. In conclusion, the arm selection preference of miRNA might be a mechanism to modulate its biological function. The findings of this study provide a novel insight into lung cancer therapy.