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標題: | 第二型去乙醯化蛋白質在口腔致癌機轉中扮演的角色 The Roles of Histone Deacetylase 2 in Tumorigenesis of Oral Cancer |
作者: | Tsung-Han Hsieh 謝宗翰 |
指導教授: | 郭彥彬(Mark Yen-Ping Kuo) |
關鍵字: | 口腔癌,第二型去乙醯化蛋白質,第一型缺氧誘導因子,惡性轉移, oral cancer,metastasis,HDAC2,HIF-1α,ANGPTL4, |
出版年 : | 2009 |
學位: | 碩士 |
摘要: | 口腔癌為世界十大癌症之一,每年有超過五十萬的的病例被報導出來,釐清口腔癌的致病機轉為目前刻不容緩的課題。先前實驗室在口腔癌臨床病人的檢體中發現第二型組蛋白去乙醯化酶(Histone deacetylase 2, HDAC2)的表現與腫瘤組織的惡性度成正相關,因此本研究擬了解HDAC2在口腔癌癌化過程所扮演的角色及機轉。初步分析六株口腔癌細胞株,發現SAS細胞株的HDAC2有過量表現;HSC3細胞株表現量為最低。利用RNA干擾SAS細胞株HDAC2表現或於HSC3細胞株過量表現HDAC2的方法改變其表現量,並進行接下來的分析。 結果發現,SAS細胞的HDAC2被抑制以後,其生長速率下降、株落形成能力減弱、細胞週期發生G1停滯的現象,且其移行及侵犯組織的能力也明顯減弱; 然而,於HSC3細胞過量表現HDAC2後,其生長速率增加、株落形成能力增強,且其移行及侵犯能力更是明顯提升。 為了深入探討HDAC2於癌化的分子機轉中扮演的角色,利用人類基因晶片進行全面性的分析,發現有大量的缺氧型誘導基因同時被HDAC2調控。由進一步實驗結果得知,HDAC2會與HIF-1α結合,並利用去乙醯化的方式切掉K532上的乙醯基,避免其被透過VHL和ubiquitin調節機制標定而水解,進而維持HIF-1α在細胞中的穩定性。 大量累積在細胞質中的HIF-1α,會進行核轉移並活化缺氧誘導基因的轉錄,這些基因參與了腫瘤細胞的生存及轉移,包括: MMPs, Collagenases, CCLs, and ANGPTL4等。 其中,研究證實ANGPTL4的表現量確實經由HDAC2-HIF-1α的轉錄活化路徑所調控,且ANGPTL4也參與了口腔癌細胞的移行與侵犯。 原位(buccal mucosa)接種腫瘤細胞的動物模式中,抑制HDAC2的腫瘤生長速率較慢且淋巴結轉移的發生率較低; 然而,HDAC2過量表現的腫瘤生長速率較快,且發生嚴重的惡性淋巴結轉移。 本研究初步釐清了HDAC2在腫瘤組織發展中所扮演的角色,並期待研發出專一性HDAC2與HIF-1α的口腔癌治療策略。 Oral squamous-cell carcinoma (OSCC) is one of the 10 most frequent cancers worldwide with more than half a million patients being diagnosed each year. Based on our previous study, over 70 % OSCC patients with HDAC2 over-expression were founded. Therefore, the roles of HDAC2 in tumorigenesis were elucidated in this study. We first screened six oral cancer cell lines and found that SAS cells with high expression of HDAC2 but HSC3 cells with low expression. Accordingly, HDAC2 knockdown stable line in SAS and HDAC over-expression stable line in HSC3 were established. SAS cells with HDAC2 knockdown showed slow growth rate, weak colony forming ability, and low metastatic potential in vitro. In contrast, HSC3 cells with HDAC2 over-expression presented fast growth rate, strong colony forming ability, and high metastatic potential in vitro. To illuminate the molecular mechanisms of HDAC2, we performed the whole human genome microarray which displayed that abundant hypoxia-associated genes were regulated by HDAC2. An important molecular regulation was revealed: HDAC2 stabilized HIF-1α protein through deacetylaton of the acetyl group on lysine 532 residue at normoxia and then the deacetylated HIF-1α protein would evade the VHL-ubiquitin-mediated degradation pathway. Considerable HIF-1α proteins accumulated in cytoplasm and also translocated into nucleus for transcriptional activation of hypoxia-induced genes, including MMPs, Collagenases, CCLs, and ANGPTL4. These pro-metastatic proteins facilitated cell survival, migration, invasion, intrvasation, and extravasation have been studied. We further investigated that ANGPTL4 protein involved in tumor migration and invasion in vitro and also confirm that the transcriptional activation of ANGPTL4 was regulated through HDAC2-HIF-1α-mediated pathway. In orthptopic (buccal mucosa injection) animal model, SAS cells with HDAC2 knockdown were low tumorigenesis and weak lymph node metastasis compared with vector controls in vivo, whereas HSC3 cells with HDAC2 over-expression were strong ability for tumorigenesis, growth and high lymph node metastasis compared with controls. Finally, we elucidated the multiple roles of HDAC2 in tumorigenesis and metastatic progression. Targeting of HDAC2 and HIF-1α are a novel strategy for oral cancer therapy. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/44293 |
全文授權: | 有償授權 |
顯示於系所單位: | 口腔生物科學研究所 |
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