探討肝癌基因之異常突變-針對HER基因家族之研究

Analysis of cytogenetic alterations in Hepatocellular Carcinoma - major focus on HER family genes

陳慧雯(Hui-Wen Chen)

指導教授 ： 翁文慧

國立臺北科技大學/工程學院/生物科技研究所/碩士(2010年)

https://doi.org/10.6841/NTUT.2010.00549

摘要

肝癌(hepatocellular carcinoma)為世界上常見的惡性腫瘤之一，其發生率排名在所有癌症中為第五名，目前估計大約有75%的肝癌好發於東南亞及撒哈拉以南的非洲國家。然而，肝癌在西方國家較不常見，這顯示開發中國家較工業國家之民眾較易罹患此重大疾病。人類表皮生長接受器家族(human epidermal growth factor receptor family, EGFR/HER family) 總共有四個成員，這四個成員分別是HER1、HER2、HER3已及HER4。研究已知，HER1及HER2這兩個HER家族基因在很多種類的癌症常有過度表達情形產生。當此兩個基因於癌症中呈現過度表達時可使正常細胞持續性增殖、分化進而演變成癌細胞並產生侵犯、轉移、抗細胞凋亡、及血管生成等癌化現象。因此，HER1及HER2為目前廣泛應用於臨床上癌症預測的指標。據研究文獻指出，HER3基因與其它三個HER家族基因成員功能截然不同， HER3蛋白因為缺乏intrinsic tyrosine kinase的活性，故須與其他HER家族成員結合，才可使下游路徑訊息傳遞功能被活化，進而產生反應。這些反應包括了使腫瘤細胞增殖、轉移、產生侵犯、抗細胞凋亡以及增加血管生成等。高表達的HER3曾在乳癌、卵巢癌、肺癌被報導過，其與肝癌的關係也經由科學家利用免疫染色法得到了進一步的證實，實驗的結果指出HER3蛋白質表現量的增加與否和腫瘤細胞增生的活性、腫瘤的大小、腫瘤細胞是否於肝內轉移、是否侵入肝門靜脈、以及腫瘤的分化等有一定程度上的相關性。藉此，我們推測不僅是HER1，HER3在肝癌中也扮演了重要的腳色。而為了應證這個推論我們利用螢光原位雜合技術 (Fluorescence in situ hybridization )分析了HER1及HER3基因於六株肝癌細胞株及二十個臨床腫瘤樣本中基因層次上數量及結構之改變。結果發現，HER1、HER3基因於六株細胞株中呈現了高表達的情形，其中以Tong細胞株最為明顯。除了基因數量的差異外，基因結構也出現了改變。另外，HER1及HER3基因於20個臨床樣本中所得到的結果與細胞株實驗結果剛好相反，在20個臨床樣本中有19個同時表現了基因HER1及HER3缺失的現象。我們推測，也許在肝癌中存在著不同的分子類型影響著病人的預後發展。

關鍵字

肝癌 ； 表皮生長因子接受器 ； 螢光原位雜合技術

並列摘要

Hepatocellular carcinoma (HCC) is the fifth most common cancer in the world. The incidence rate is much higher in developing countries than in industrialized countries. More than 75% of HCC cases occur in the Southeast Asia and sub-Saharan Africa.
There are four members belong to human epidermal growth factor receptor (EGFR; HER) family : EGFR( HER1)、HER2、HER3、HER4. Overexpression of HER1 and HER2 were found in so many types cancers including HCC. They lead the cells proliferation、differention、invasion、metastasis、antiapoptosis and angiogenesis of cancer cells. Therefore, HER1 and HER2 have been widely predicted as a biomarker in clinical purpose. To our knowledge, HER3 is different from other HER family
members. It requires heterodimerization with the other HER family members to trigger the signaling transduction. Further, the signal transction cascades involve in the tumor cell proliferation, migration, invasion, anti-apoptosis, and increased angiogenesis.The high level expression of HER3 has been observed in breast, ovarian, and lung cancer. Expression of HER3 protein in HCC using immunohistochemistry was further shown to be related to cell proliferation, intrahepatic metastasis, portal invasion and carcinoma differentiation. Accordingly, we hypothesized that not only HER1 but also HER3 may play an important role in HCC. By analyzing the gene expression level of HER1 and HER3 in six HCC cell lines and twenty paraffin tissue samples, we found that the expression level of two genes were correlated with gene structures and/or gene copy number alterations. Notably, HER3 presented either the different level of copy number changes or gene structure alterations in all six cell lines. In addition, HER1 and HER3 genes were highly expressed in Tong cell line when compared to other HCC cell lines. The FISH results showed the alteration of genes structure and increased copy number of HER1 and HER3 genes in all cell lines. While the study on the clinical HCC samples revealed that the gene structural aberrations were more common than gene copy number alterations. Most of the clinical samples presented one copy of HER1 and HER3 genes. However, further evidence from larger clinical samples is needed to clarify our current findings.

並列關鍵字

HER1 ； HER2 ； HER3 ； HER4 ； hepatocellular carcinoma ； Fluorescence in situ hybridization

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