- 學位論文
RECK與Jab1為HER-2/neu引發腫瘤生成之關鍵調控因子
RECK and Jab1 are key mediators of HER-2/neu-induced tumorigenesis
摘要
Her-2/neu (亦稱為c-erbB-2) 屬於表皮生長因子接受器(epidermal growth factor receptor family)的一個成員，正常情況下當Her-2/neu活化後會調控細胞生長;但若Her-2/neu過度表現則會造成細胞過度增生及增加細胞侵犯轉移之能力。Her-2/neu 的基因擴增或過度表現常常被發現於癌症細胞，包括乳癌、卵巢癌、肺癌、胃癌、結腸癌等;目前認為Her-2/neu 的基因擴增或過度表現會影響腫瘤生長能力，使腫瘤更具侵襲性，增加腫瘤轉移的能力及血管新生。 Her-2/neu 是一個原致癌基因，當它活化之後會經由下游不同的訊息傳遞途徑，調控細胞內許多基因的表現。Her-2/neu參與多種細胞功能的調控，例如影響細胞週期的進行、細胞生長、癌細胞的轉移及血管新生等;我們的實驗結果新發現兩個Her-2/neu調控之下游基因─RECK與Jab1，並深入探討Her-2/neu如何調控腫瘤抑制基因RECK與致癌基因Jab1表現之機轉。第I部份研究發現Her-2/neu經由ERK訊息路徑與Sp 轉錄因子抑制腫瘤轉移抑制基因RECK的表現，促進腫瘤細胞侵犯性。第Ⅱ部份研究顯示在Her-2/neu 促進p27蛋白質分解及細胞增生過程中Jab1扮演一個關鍵因子。 第I部份探討Her-2/neu如何調控RECK基因的表現，這部份的研究結果發現Her-2/neu會經由活化ERK訊息傳遞路徑，造成轉錄因子Sp1的兩個胺基酸Thr453與Thr739磷酸化，增加Sp1與RECK啟動子上Sp1結合位置之結合能力，進一步與HDAC1形成複合物，抑制RECK基因轉錄活性，減少細胞表面RECK的表現量，因此增加MMPs的活性及其之釋放，造成細胞侵犯能力的增加。 在第Ⅱ部份，我們的研究發現Her-2/neu會經由PI3K/AKT訊息傳遞途徑促使TCF-4/β-catenin轉錄因子複合體結合到Jab1基因啟動子上的TCF-4結合位，造成Jab1表現增加進一步將p27從細胞核運送到細胞質並且進行蛋白質分解，致使p27無法在細胞核中發揮其抑制細胞週期進行的功能，最後造成細胞增生。相反的，若利用siRNA去干擾Jab1 mRNA 表現，讓Jab1表現量減少，反而會造成細胞核中p27 蛋白質表現量增加，並且抑制細胞生長。另外病理組織染色結果發現66個乳癌病人的腫瘤組織中有53個檢體(80.3%)其Jab1為過度表現並且統計結果顯示Her-2/neu與Jab1的表現具有明顯相關性(p=0.0318)。此外研究結果也發現在Her-2/neu過度表現的人類乳癌細胞MDA-MB-453中Jab1表現較MCF-7人類乳癌細胞高，並且證實Jab1為Her-2/neu下游之調控基因。
並列摘要
Her-2/neu ( known as c-erbB2) belongs to epidermal growth factor receptor gene family. After Her-2/neu is activated, it will induce cell proliferation. Overexpression of Her-2/neu promotes cell over-proliferation and enhances metastatic potential. Overexpression or gene amplification of HER-2/neu has been reported frequently in many types of human cancer, including breast, ovary, lung, stomach and colon cancer. Overexpression or gene amplification of HER-2/neu enhances tumor cell proliferation, metastatic potential and tumor angiogenesis. Her-2/neu is a pro-oncongene and may regulate expression of many target genes through different signaling pathways after activation. Her-2/neu regulates various biological functions of cells, such as cell cycle progression, proliferation, metastasis and angiogenesis via activation of these molecular effectors. In this study, I identify two target genes for Her-2/neu and study the mechanism of gene regulation and biological function. In part I, i identified the mechanism of Her-2/neu-induced repression of RECK gene. My study has shown that ERKs, a major downstream target of Her-2/neu signaling pathway, phosphorylated Thr453 and Thr739 of Sp1 protein to enhance its DNA binding activity and induced recruitment of HDAC1 which repressed transcription of RECK gene. The reduction of RECK increases enzyme activity and release of MMPs to promote tumor cell invasion. In part Ⅱ, my data have shown that Her-2/neu promoted TCF-4/β-catenin complex to bind to the TCF-4 binding site of Jab1 promoter via PI3K/AKT signaling pathway. Her-2/neu induced Jab1 expression and subsequently led to the translocation of p27 from nucleus to cytoplasm where p27 was degraded through 26S proteasome pathway. The mislocation or degradation of p27 attenuated its ability to inhibit cell cycle progression and suppress cell proliferation. Conversely, knockdown of Jab1 by using siRNA increased p27 protein level which inhibited cell proliferation. In immunohistochemical study, we demonstrated that Jab1 is overexpressed in 53 (80.3%) of a series of 66 human breast tumor tissues and its expression is significantly correlated with HER-2/neu overexpression (p=0.0318). In addition, our study showed that HER-2/neu-overexpressing MDA-MB-453 human breast cancer cells exhibited higher expression of Jab1 than that of MCF-7 breast cancer cells and Jab1 is a downstream target for HER-2/neu in human breast cancer cells. Taken together, RECK and Jab1 are key mediators of HER-2/neu-induced tumorigenesis.
參考文獻
延伸閱讀
- Chou, S. F. (2015). 探討具雙重功能之ESCRT-0因子HGS影響B型肝炎病毒轉錄與核心蛋白顆粒釋放之能力 [doctoral dissertation, National Taiwan University]. Airiti Library. https://doi.org/10.6342/NTU.2015.10042
- 劉家豪（2014）。在傷害誘導的JA訊息傳遞過程中，WRKY26, WRKY38 和 MYC2是調控ORA47基因表現的上游轉錄因子〔碩士論文，國立臺灣大學〕。華藝線上圖書館。https://doi.org/10.6342/NTU.2014.02224
- 蔡宗霖（2004）。血清中腫瘤標記HER-2/neu及SCCA值與口腔鱗狀細胞癌關聯性的研究〔碩士論文，高雄醫學大學〕。華藝線上圖書館。https://www.airitilibrary.com/Article/Detail?DocID=U0011-2903200614000180
- Giampietri, C., Petrungaro, S., Conti, S., Facchiano, A., Filippini, A., & Ziparo, E. (2015). Cancer Microenvironment and Endoplasmic Reticulum Stress Response. Mediators of Inflammation, 2015(), 936-946-189. https://doi.org/10.1155/2015/417281
- Lyadova, I. V., & Panteleev, A. V. (2015). Th1 and Th17 Cells in Tuberculosis: Protection, Pathology, and Biomarkers. Mediators of Inflammation, 2015(), 563-575-452. https://doi.org/10.1155/2015/854507