肝細胞癌組織中plectin缺乏對細胞角質18穩定性的影響

The Influence of Plectin Deficiency on Stability of Cytokeratin18 in Hepatocellular Carcinoma

鄭瓊姬(Chiung-Chi Cheng)

指導教授 ： 賴義雄

中山醫學大學/醫學院/醫學研究所/博士(2008年)

https://doi.org/10.6834/CSMU.2008.00058

摘要

細胞骨架於細胞的功能上擔任重要的角色，暗示著在許多人類的肝病包括惡性腫瘤的致病機轉中扮演重要的任務。我們之前研究探討過有關人類肝細胞癌中腫瘤轉變時細胞角質的安定性，結果顯示人類肝細胞癌中細胞角質已被調整。中間絲(在肝細胞的組成是細胞角質8和18)已被認為與許多細胞的成分交互作用。這些交互作用可以經由橫向連結蛋白質，例如plectin。Plectin是數種中間絲相關蛋白質的一種，是一種應用自如的細胞質的交互連結者，連結中間絲和微小管，微細絲和細胞膜黏著點，可以將細胞骨架組合成ㄧ安定的網狀結構支撐及維持細胞的大小和形狀。根據肝細胞癌的細胞形態與正常肝細胞不同，於是我們提出一個假說，plectin表現降低(down regulation)與細胞角質18被調整有關聯，進而導致細胞骨架瓦解。也就是說，經由影響細胞骨架的架構，plectin在肝細胞癌的腫瘤成因上也許是一個重要的關鍵。本論文以二個研究主題探討人類肝細胞癌中橫向連結蛋白質plectin和中間絲主成分細胞角質18之間的關聯性。首先，研究-A探討：肝細胞癌組織中plectin的降解對細胞角質18穩定性的影響。利用人類肝細胞株Chang cells進行plectin siRNA轉染，降低細胞中plectin蛋白質的合成，藉由西方點墨法及免疫螢光染色法觀察細胞角質18的穩定性是否受到影響。研究-B探討：利用staurosporine藥物處理模擬細胞內部引發細胞凋亡產生，藉由西方點墨法及免疫螢光染色法觀察觀察plectin和細胞角質18之間相互作用的影響。結果顯示在肝細胞癌中plectin發生缺乏後使細胞角質18被調整，並且在細胞凋亡過程中plectin被切割進一步影響細胞角質18。結論是一旦plectin發生缺乏或是降解時，就會影響細胞角質18的穩定性。因此，我們推測plectin在肝細胞癌癌化過程中扮演著關鍵性角色。

關鍵字

細胞角質18 ； Plectin ； 中間絲 ； 肝細胞癌 ； 細胞骨架

並列摘要

The cytoskeletons play important roles in cell function and therefore are implicated in the pathogenesis of many human liver diseases, including malignant tumors. Previously, we studied the stability of cytokeratin during tumor transformation in human hepatocellular carcinoma, the results demonstrated that cytokeratin18 was modulated in human hepatocellular carcinomas. Intermediate filaments (in liver cells, they are mainly cytokeratin 8 and 18) have been proposed to interact with many cell components, these interactions may be via cross-linking proteins such as Plectin. Plectin is one of several intermediate filaments associated proteins and it is proposed to be a versatile cytoplasmic cross-linker connecting intermediate filaments to microtubules, microfilaments and membrane adhesion sites. It might organize the cytoskeleton into a stable meshwork, which can maintain the uniform size and shape of hepatocyte. According to the morphological difference between hepatoma cells and normal liver cells, we raised a hypothesis that the down-regulation of Plectin might relat to CK18 modulation and could cause disorganization of cytoskeleton, which resulted in pleomorphism of hepatoma cells. That is, via affecting the organization of cytoskeleton, Plectin might be an important issue in tumorigenesis of hepatocellular carcinoma. In here, we raised two objects to explore the expression of cross-linking proteins, Plectin, and intermediate filament elements, cytokeratin, in human hepatocellular carcinoma. First, the purpose of object one was “The influence of Plectin deficiency on stability of cytokeratin18 in hepatocellular carcinoma”. We performed knockdown Plectin mRNA by Plectin siRNA transfection in Chang cells to understand the expression changes of CK18 during Plectin deficiency. The purpose of second object was the “Degradation of Plectin with modulation of cytokeratin18 in human liver cells during Staurosporine induced apoptosis”. Mainly to observe the degradation of Plectin might affect the relationship with CK18 when Plectin mRNA was deficient. The results revealed that plectin was deficient and cytokeratin18 was modulated in hepatocellular carcinoma. Plectin was cleaved in the liver cells during apoptosis and CK18 was modulated. In conclusion, the Plectin deficiency could affect CK18 stability and disrupt the organization of intermediate filament meshwork and further result in morphological changes of cancer cells. That is, the Plectin might play an important role in tumorigenesis of hepatocellular carcinoma.

並列關鍵字

Cytokeratin ； Plectin ； Intermediate filament ； Hepatocellular carcinoma ； Cytoskeleton

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