因為台灣是B型肝炎 (Hepatitis virus B infection, HBV) 的盛行區域，所以肝癌 (Hepatocellular carcinoma, HCC) 在台灣的發生率很高。在台灣，惡性腫瘤數年來一直位處國人十大死因之榜首，而肝癌是惡性腫瘤中的第二位。因為期別是重要的預後因子，所以早期診斷可以改善肝癌的存活率。甲型胎兒蛋白 (alpha-fetoprotein, AFP) 是目前診斷及追蹤治療肝癌的最重要的腫瘤標誌。可是甲型胎兒蛋白對肝癌診斷的敏感性、特異性及陽性預測率卻不是令人很滿意。細胞週期抑制劑 p27kip1的表現量降低與肝癌的不好預後明顯相關，所以p27kip1已被證明為可能的肝癌的重要預後因子。而p27kip1的表現量降低是因為p27kip1經由ubiquiting-proteosome系統的降解增加所致。在許多的報導中曾證實Skp2 (S-phase kinase associated protein 2) 與其輔助因子Cks1 (Cyclin-dependent kinase subunit 1) 是p27kip1經由 ubiquiting-proteosome系統的降解反應中必要的ubiquitin接合酶。在很多人類惡性腫瘤中都可發現Skp2與Cks1的表現量增加。可是從來沒有研究曾經報導過p27kip1、Skp2與Cks1這三種蛋白質的表現量在肝癌中的關係及預後角色。在本研究中，我們就研究p27kip1、Skp2與Cks1這三種蛋白質的表現量在肝癌中的關係及預後角色。
我們使用75個肝癌病人手術後石蠟包埋的標本切片及高特異性抗體作免疫組織化學染色，來研究p27kip1、Skp2與Cks1這三種蛋白質在肝癌細胞中的表現量。同時我們也收集並分析所有病人的臨床資料，來研究p27kip1、Skp2與Cks1這三種蛋白質與臨床資料的相關性。
分化良好的肝癌傾向較高的p27kip1表現量 (55.6%)及較低的Skp2與Cks1表現量 (66.7%及77.8%)。分化不好的肝癌傾向較低的p27kip1表現量 (64.3%)。Cks1的表現量與Skp2的表現量有明顯的正相關性 (P = 0.000) 。相反地，在本研究中，我們沒有發現p27kip1的表現量與Cks1及Skp2的表現量有明顯的負相關性。p27kip1、Skp2與Cks1這三種蛋白質在肝癌細胞中的表現量與肝癌期別 (AICC TNM system及 CLIP scoring system )有明顯的相關性。此外，Skp2 和Cks1的表現量與存活率有明顯的相關性，也就是說較高Skp2與Cks1表現量的病人有較差的存活率。
本研究是第一個報告Cks1這個蛋白質在肝癌中的表現量及預測預後的角色。較高的Skp2與Cks1表現量與晚期肝癌及較差預後有明顯相關性。因此，Skp2與Cks1可以被視為可能的新的肝癌的重要預後因子及治療標靶。

The incidence of hepatocellular carcinoma (HCC) is high in Taiwan, because Taiwan is one of HBV-endemic areas. Moreover, HCCs are the 2nd most common cause of death caused by malignancies in Taiwan. Early detection of HCC can improve the survival rate because the stage is one of important prognostic factors. Alpha-fetoprotein (AFP) is the most important tumor marker for diagnosis of HCC and surveillance of treatment. However, the sensitivity, the specificity and positive predictive value of AFP are not very satisfactory. The cell cycle inhibitor p27kip1 is known as a potential prognostic marker for HCC. Decreased expression of cell cycle inhibitor p27kip1 is associated with poor prognosis in HCC. The decreased expression of p27kip1 results from increased ubiquitin-proteosome degradation. S-phase kinase associated protein (Skp2) and cyclin-dependent kinase subunit 1 (Cks1) are the subunits of the ubiquitin ligases responsible for the ubiquitin-proteosome degradation of p27kip1. The increased expression of Skp2 and Cks1 were found in many kinds of human cancers. However, there is no report about the relationship between Cks1, Skp2 and p27kip1 expression in hepatocellular carcinoma. In the present study, we investigated the expression of Cks1, Skp2 and p27kip1 and their prognostic roles in hepatocellular carcinoma.
We used highly specific antibodies in immunohistochemistry to examine the expressions of Cks1, Skp2, and p27kip1 on paraffin-embedded tissue section from 75 patients with hepatocellular carcinoma. Meanwhile, we also analyzed the clinical significance of these three proteins with the various clinicopathological factors and follow-up data.
Well-differentiated HCCs tended to express higher level of p27kip1 (55.6%), and lower levels of Skp2 (66.7%) and Cks1 (77.8%). Poorly differentiated HCCs tended to express lower level of p27kip1 (64.3%). The expression of Cks1 was significantly associated with the expression of Skp2 (P=0.000). In contrast, there were no inverse relationships between the expression of p27kip1 and the expressions of Skp2 and Cks1 in the present study. The expressions of p27kip1, Skp2, and Cks1 were significantly associated with disease stage (AJCC TNM stage system and CLIP scoring system). Moreover, there were significant associations between overall survival rates and the expressions of Skp2 and Cks1 (P = 0.036 and 0.015, respectively). Patients with higher expression of Skp2 and Cks1 had worse survival rates.
This is the first report of the expression and prognostic role of Cks1 in HCC. Higher expression of Skp2 and Cks1 were significantly associated with advanced stage and poor prognosis. Thus, both Skp2 and Cks1 may be considered as potential novel prognostic markers providing more accurate prediction of prognosis combined with AFP and therapeutic targets in HCCs.

Abstract
Chinese 3
English 5
Abbreviations 7
Introduction 8
Materials and Methods 16
Results 19
Discussion 25
References 28
Tables 43
Figures 49
Appendices 67

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