β-catenin控制第一型黏蛋白於乳癌細胞核運輸之探討

β-catenin-mediated nuclear localization of cytoplasmic domain of MUC1 in breast cancer

蘇厚有(Hou-Yu Su)

指導教授 ： 張育嘉

共同指導教授 ： 陳永興

臺北醫學大學/醫學院/臨床醫學研究所/碩士(2011年)

摘要

乳癌為台灣女性十大惡性腫瘤發生率的第一位，近年研究報告顯示乳癌細胞第一型黏蛋白（MUC1)過度表現且其中MUC1-CD（cytoplasmic domain of MUC1）影響細胞的基因調控，促使癌細胞生長；另一方面，β-catenin為細胞骨架的構成要素，亦是乳癌重要的致癌蛋白，透過WNT/β-catenin訊息傳遞路徑到達細胞核內影響基因調控，同時發現MUC1-CD上具有β-catenin的結合位置，故我們推測MUC1-CD可能與β-catenin於腫瘤調控中具有著某種程度的關聯。首先以免疫共沉澱法（co-immunoprecipitation）分析β-catenin及MUC1-CD的關係，發現MCF7細胞中β-catenin能結合於MUC1-CD；進一步分別利用RNAi的技術及基因大量表現的方法，抑制或增強β-catenin的表現量，並以分離細胞質與細胞核蛋白質方式，觀察MUC1-CD於細胞中分布情形及在核中的表現量變化。主要是透過了解β-catenin的表現量是否能夠影響MUC1-CD進入細胞核的比例，結果發現：於MCF7細胞中降低β-catenin的表現量後，MUC1-CD於細胞核的量亦明顯地降低；而在MDA-MB231細胞中增加β-catenin的表現量後，MUC1-CD於細胞核的量亦明顯地增加，另一方面於MCF7細胞及MDA-MB231細胞中MUC1的mRNA及MUC1-CD細胞總蛋白質的表現量無明顯改變，這個結果顯示改變β-catenin的表現量會影響MUC1-CD細胞質及細胞核的分布。由實驗的結果可以得到以下結論：乳癌細胞透過β-catenin和MUC1-CD蛋白質的交互作用控制MUC1-CD進入細胞核的比例，所以β-catenin控制MUC1-CD的細胞核運輸

關鍵字

乳癌 ； 黏蛋白 ； 核運輸

並列摘要

In Taiwan, breast cancer has been the most common malignancy in women. Recently, it is reported that the mucin 1 (MUC1) has been over-expressive on the cell membrane of breast cancer cells. The cytoplasmic domain of mucin 1 (MUC1-CD) can influence gene regulation in breast cancer. In the other hand, β-catenin is one component of the cytoskeleton. It is also an oncoprotein in relationship with WNT/β-catenin signaling pathway and influences gene regulation in breast cancer. There is a docking site on MUC1-CD for β-catenin. So, the interaction between MUC1-CD and β-catenin may influence oncogenesis in breast cancer. First, we researched the reciprocal interaction between β-catenin and MUC1-CD by co-immunoprecipitation. β-catenin can be associated with MUC1-CD intracellularly. Further, we used the techniques of RNA interference and gene over-expression to manipulate the expression of β-catenin. Additionally, we observed the changes of cytoplasmic and nuclear MUC1-CD in MCF7 and MDA-MB231 cells by compartment protein extraction. We wanted to demonstrate nuclear localization of MUC1-CD by augmenting or lowering the expression of β-catenin. It was resulted that the quantity of the nuclear MUC1-CD decreased after the expression of β-catenin was lowered in MCF7 cells. In contrast, the amount of the nuclear MUC1-CD increased after β-catenin was over-expressive in MDA-MB231 cells. In the other hand, mRNA of MUC1 and total protein of MUC1-CD were unaltered significantly in both of MCF7 and MDA-MB231 cells. Therefore, the up and down-expression of β-catenin was correlative with the quantity of MUC1-CD in the cell nucleus.It is concluded that β-catenin can control the nuclear localization of MUC1-CD by reciprocal interaction in breast cancer.

並列關鍵字

breast cancer ； MUC1 ； mucin ； catenin

參考文獻

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