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標題: | 第四型肝細胞核因子抑制肝癌細胞的增生和轉移 Hepatocyte nuclear factor 4α suppresses the proliferation and migration of hepatocellular carcinoma cells |
作者: | Ming-Te Peng 彭銘得 |
指導教授: | 林榮耀 |
關鍵字: | 第四型肝細胞核因子,肝癌,細胞增生,細胞移動與侵襲,細胞骨架,間質蛋白,細胞週期素與細胞週期蛋白依賴性激酶,抑制因子, HNF4α,HCC,migration,invasion,cytoskeletons,p21,CCND1,fibronectin,N-cadherin,Rac1,Cdc42, |
出版年 : | 2011 |
學位: | 碩士 |
摘要: | 肝癌是全世界最常發生的癌症之一,在台灣,肝癌自2004年列居癌症死亡病史第二位。雖然目前已有許多治療方式,但由於肝癌細胞易造成對鄰近組織與其他器官的高轉移性,使得肝癌患者的病情不甚樂觀。在普遍的癌細胞移動和侵襲過程中,通常地必須仰賴其細胞骨架的異常調控的機制作用以驅使細胞前進。
第四型肝細胞核因子(Hepatocyte nuclear factor 4α, HNF4α)是一種轉錄因子,調控許多參與細胞分化和正常肝細胞功能的基因表現,抑制細胞上皮-間質轉化(epithelial-mesenchymal transition, EMT)過程。近來研究亦認為HNF4α的表現量降低與肝癌細胞的演進過程有高度關聯性。為了深入探討HNF4α在癌細胞中調控的機制,我們利用基因重組的質體對低表現HNF4α的肝癌細胞株(SK-Hep1)增加HNF4α表現的影響,同時也使用核醣核酸(shRNA)專一性地對高表現HNF4α的肝癌細胞株(Huh6)抑制HNF4α的表現。研究發現HNF4α對細胞增生、週期、移動和侵襲的能力與細胞骨架之聚合方面皆表現了明顯抑制的作用。 在細胞生長方面,HNF4α可活化細胞週期蛋白依賴性激酶抑制因子(p21)的表現量,同時也抑制細胞週期素(Cyclin D1)和細胞週期蛋白依賴性激酶(Cdk1),使得細胞週期停止在G0/G1期,達到抑制細胞增生的效果。另一方面,HNF4α抑制間質蛋白(N-cadherin和Fibronectin)的表現量;由Fibronectin所活化的下游訊息傳遞分子FAK與Src,活性也因此降低。此外,HNF4α亦減低Cdc42的表現並造成Cofilin的活性上升,使得肌動蛋白纖維的聚合作用受到抑制;由雷射掃描共軛焦顯微鏡的觀察和肌動蛋白的分析結果顯示,表現HNF4α的細胞內,G-肌動蛋白單體比率提升,而纖維狀的F-肌動蛋白所佔比率則下降。 綜合上述,本研究結果顯示HNF4α表現的減少或喪失,將活化Fibronectin下游的訊息傳遞以促進細胞生長、移動與侵襲的能力和細胞骨架的聚合。因此,在肝癌細胞的增生/轉移過程中,HNF4α表現量的減少確實形成了重要的關鍵之一。 Liver cancer is one of the leading cause of cancer and the second highest incidence of cancer death in Taiwan. Hepatocellular carcinoma (HCC) is a primary malignancy of the liver with poor prognosis, caused by metastatic cancers relapse. Hepatocyte nuclear factor 4α (HNF4α) is a transcription factor which has been shown to be down regulated in HCC. In this study, to address the role of HNF4α during the progression of HCC, an HNF4α expression plasmid was generated to study its effects on hepatoma cell lines (SK-Hep1with low expression of HNF4α), whereas shRNA was used on hepatoma cells Huh6 with high expression of HNF4α. The results showed that the gene expression level of HNF4α is correlated with epithelial phenotype and inversely associated with cell viability, cell cycle progression, organization of actin filament, migratory and invasive capacities of HCC cells. The suppressive effects of HNF4α on proliferation are achieved by up-regulating the expression of p21 and down-regulating the expression of cyclin D1 and cyclin dependent kinase 1 (Cdk1). Additionally, the expression of N-cadherin and fibronectin was down-regulated by HNF4α in HCC cells. We further examined the effects of HNF4α on focal adhesion kinase (FAK) and Src, and the results showed that knock-down of HNF4α expression had a significant activation effect on FAK and Src in HCC cells. Moreover, HNF4α also displayed significant suppressive effects on cell mobility by down regulation of Cdc42 expression and Rac1 activity to inhibit the formation of actin stress fiber. Down-regulation of cytoskeletons has been strongly implicated in HCC progression, particularly in cell migration and cell invasion. Taken together, the results indicate that HNF4α functions as an tumor suppressor gene and plays a role in proliferation, actin cytoskeletons, cell migration and invasion, in part via down regulating CCND1, Cdk1, fibronectin, p-FAK, p-Src, Rac1, N-cadherin and Cdc42. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/48495 |
全文授權: | 有償授權 |
顯示於系所單位: | 生物化學暨分子生物學科研究所 |
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