探討在台灣地區白血病人中基因以及異基因的改變模式

Studying of the genetic and epigenetic alteration in leukemia in Taiwan

蔡靜怡(Ching-Yi Tsai)

指導教授 ： 許立松

中山醫學大學/醫學院/生化暨生物科技研究所/碩士(2006年)

摘要

前致癌基因的改變參與在許多的癌症的形成，在這些前致癌基因中ras基因已被證實在白血病病患中有突變情形，另外一個多功能的基因β-catenin常在大腸直腸癌產生突變的現象。除了基因的改變外，異基因的改變如DNA的甲基化在癌症形成也扮演一個重要角色。例如：EDNRB基因(endothelin receptor B)在許多的癌症中發現其啟動子(promoter)處會發生不正常的甲基化，但是在白血病人中則較少被討論；p16INK4a會對細胞週期進行抑制性的調節，研究顯示，p16INK4a的啟動子(promoter)區域呈現CpG island高度甲基化，促成癌症的生成，也被認為會影響白血病的形成。本篇研究利用DNA作序列分析32位白血病病患中ras及β-catenin基因突變情形，結果顯示在白血病人中，其中6%(2/32)的病人 N-ras產生突變，而有31%(10/32)的病人其K-ras發生突變，另外13%(4/32)的白血病人其β-catenin基因有產生突變的現象。除此以外，本篇研究，利用甲基化專一性聚合酶連鎖反應(methylation-specific PCR)分析白血病人中EDNRB及p16INK4a其啟動子(promoter)區域甲基化的狀態，實驗結果顯示，有72%(23/32)白血病人其EDNRB基因啟動子(promoter)的CpG island發生異常甲基化，有63%(20/32)的白血病人其p16INK4a基因啟動子(promoter)的CpG island有甲基化的現象，結果也同時觀察到EDNRB及p16INK4a其啟動子(promoter)區域甲基化並未與年齡、性別以及疾病類別有任何的相關性。

關鍵字

基因性 ； 異基因性 ； 甲基化 ； 白血病

並列摘要

The genetic alteration of proto-oncogenes has been proposed to be involved in carcinogenesis in different cancers. The mutation of one of these oncogenes, ras, was frequently observed in leukemia patients. The mutation of another multiple functional signaling molecule,β-catenin was also observed in some cancers such as colorectal cancer. Besides the genetic alteration, epigenetic alteration such as DNA methylation also may be contributed to cancer development. For example, methylation of the promoter of EDNRB (endothelin receptor B) gene was observed in many different cancers, though little is known about its role in leukemia. p16INK4a can inhibit the cell cycle progression, and some studies suggest the promoter methylation of p16INK4a may be involved in the development of different cancer, including the leukemia. In this study, we collected blood specimens from thirty-two leukemia patients and determined the mutation stautus of ras and β-catenin. Our results revealed the N-ras, K-ras and β-catenin mutation was observed in 6%(3/32), 31%(10/32) and 13%(4/32) leukemia patients respectively. In addition, we have analyzed the promoter methylation status of EDNRB and p16INK4a genes by methylation-specific PCR. Our results showed the promoter DNA methylation of EDNRB and p16INK4a genes was observed in 72%(23/32) and 63%(20/32) leukemia patients respectively. These DNA methylations were not associated patients’ age, gender, and leukemia classification.

並列關鍵字

genetic ； epigenetic ； methylation ； leukemia ； EDNRB ； p16INK4a ； ras ； β-catenin

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