探討ENO1 (α enolase)在乳癌細胞中所扮演之角色與Tamoxifn 活化ENO1(α enolase) 蛋白表現之機制

Studies on the role of α-enolase(ENO1) in Breast Cancer and its Molecular Mechanism of Tamoxifen Induces α-enolase Protein Expression

張志強(Chih-Chiang Chang)

指導教授 ： 楊沂淵

共同指導教授 ： 何元順(Yuan-Soon Ho)

臺北醫學大學/醫學院/醫學科學研究所/碩士(2008年)

摘要

ENO1是一個存在於細胞質的糖解作用酵素，主要功能在於催化phosphoenolpyruvate 形成。但在近幾年的研究中指出ENO1是一個多功能性蛋白，在哺乳動物中，目前發現三種不同的isoform，分別為enolase-α(ENO1)、enolase-β(ENO3)、enolase-γ(ENO2)。ENO1存在於大部份的組織中，ENO2、ENO3主要存在於神經細胞或肌肉細胞中。這一些isoform是具有組織特異性的，它們一般以homodimers 或heterodimers 形式作用，使2-phosphoglycerate 變成 phosphoenolpyruvate。ENO1跟c-myc binding protein 1(MBP-1) 來自於相同的一個基因，經由不同的轉譯修飾過程所產生。在本實驗中我們證實Tamoxifen 在MCF-7細胞中，可以活化ENO1蛋白之表現，實驗中我們也有發現Tamoxifen 活化NFκB、ER α、ER α p118等蛋白之表現。在尋找轉錄因子結合位的Database(TFSEARCH: Searching Transcription Factor Binding Sites)上，我們發現到ENO1 轉錄調控區有轉錄因子NFκB的結合位。核質分離技術證實加入Tamoxifen可以使NFκB被活化，而進到細胞核裡面。接著使用NFκB的活化抑制劑PDTC，發現到當NFκB被抑制之後， ENO1的表現量下降了。在此我們證實Tamoxifen可以經由轉錄因子NFκB，結合到ENO1的轉錄調控區，因而活化ENO1蛋白之表現。利用即時性PCR(Real-time PCR)定量mRNA 的表現量，發現腫瘤組織中ENO1的表現量有明顯高於正常組織中的ENO1。在乳癌病人的病理切片中，我們有發現到在乳癌病人的乳腺管癌化的細胞中表現量比較多。因此我們認為ENO1 乳癌細胞中大量表現，一定具有臨床上的意義。

關鍵字

乳癌

並列摘要

Enolase α(ENO1) is a cytoplasmic glycolytic enzyme involved in the formation of phosphoenolpyruvate. More recent evidence, however ,shows that Enolase is a multifunction protein.In mammalian cells,three isoforms of enolase have been found. There are designated as enolase-α(ENO1)、enolase-β(ENO3)、enolase-γ(ENO2).ENO1 is widely distributed in a variety of tissues, whereas ENO2 and ENO3 are exclusively found in neuron/neuronendocrine and muscles tissues, respectively. The expression of the those isoforms is developmentally regulated in a tissue-specific manner.Enolases from heterodimers or homodimers to convert 2-phosphoglycerate into phosphoenolpyruvate in glycolysis. Enolase αand c-myc binding protein originate from a single gene through alternative use of translational starting site. We previously demonstrated that Tamoxifen induces ENO1 expression in MCF-7 cell line. In this report, we found Tamoxifen induces ENO1、ERα、ERα p118、NFκB protein expression. In the database (TFSEARCH: Searching Transcription Factor Binding Sites),we found NFκB binding site in ENO1 promoter. Nuclear extraction suggested that Tamoxifen inducing NFκB translocation into nuclear. We use PDTC, a NFκB inhibitor, blocks NFκB tronslocation into nucleus. PDTC inhibitor was down-regulated ENO1 protein expression. We investigated NFκB regulation ENO1 expression by binding on ENO1 promoter.Quantitative assays of the mRNA levels of the ENO1 was measured by Real-time PCR analysis technique and revealed that expression of the ENO1 was higher in tumor tissue when compared to normal tissue which dissected form the tumor margin. Tissue section from patients with breast caner were examined Immunohistochemically. We found ENO1 overexpression in breast ductal carcinoma.

並列關鍵字

ENO1 ； α enolase ； breast cancer

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