國立臺灣大學醫學院外科李章銘2006-07-262018-07-112006-07-262018-07-112004-07-31http://ntur.lib.ntu.edu.tw//handle/246246/24520食道癌的發生與環境和遺傳因子有密切的關係。在我們過去的研究中發現，吸煙、喝洒、 嚼檳榔在台灣可增加食道癌的致癌危險性，這三種環境因子，彼此間有明顯的加成作用。另一 方面，個體在先天的遺傳變異，也可左右食道癌發生的風險，各種解毒酵素，如GSTP1、P53 腫瘤抑制基因，基因修輔酵素如XRCC1、hOGG1 等遺傳因子之基因多型式，亦可決定個體對 食道癌的易感受性。由於各種環境毒物，大部份都是透過對基因的損傷而促成癌化的作用，因 此基因修補酵素的正常功能可能在癌化的預防的過程中，扮演著重要的角色，因此本研究將進 一步探討hOGG1 在食道癌癌化與腫瘤行為的角色。我們假設hOGG1 的功能變異，包括遺傳 子喪失、基因多型式、蛋白質表現可影響食道組織基因修補能力，而導致食道癌癌化、機轉之 啟動。 在過去兩年中，我們完成了hOGG1 基因多型性的基因檢定，我們發現hOGG1 具有cys 遺傳子者，分別在沒有嚼食檳榔、沒有飲酒及沒有抽煙習慣的個體中，可增加其罹患食道癌的 危險性。其OR（95﹪信賴區間）分別為：1.86（1.08-5.31）及3.09（1.22-7.81）。我們也在病 患腫瘤檢體中，測定了hOGG1 於Exon 7 及intron 4 等遺傳位置之遺傳子喪失的情形，我們發 現食道癌在這些區域，有極高的比例有遺傳子喪失的情形，其比例分別為55.66﹪（Exon 7） 及62.22﹪（intron 4）。在免疫螢光染色中，我們也發現了將近82﹪的腫瘤不表現hOGG1 腫 瘤蛋白。我們的研究顯示hOGG1 基因功能改變或是喪失在食道癌發展的過程中扮演著重要角 色。而hOGG1 遺傳位置基因體的喪失，可影響食道癌病患治療的療效，在hOGG1 Exon 有基 因體喪失(LOH)病患在治療後，有較好的療效，另一方面在Intron 4 產生deletion，則病患治療 的癒後則較不理想。在exon 7 hOGG1 LOH 的作用，以抽煙、喝酒族群的病患，作用較明顯， 而Intron 4 作用則是於非抽煙、喝酒、嚼檳榔的病患較明顯。本研究顯示hOGG1 的功能不只 影響健康者，產生食道癌的危險性，且進一步能影響腫瘤的細胞行為，而決定病患的癒後。 爲了探討hOGG1 的細胞生理學意義，以便解釋其對食道癌治療後之存活率的影響，我們 使用了CE81T/VGH 及CE48T/VGH 兩株食道癌細胞，檢測抑制hOGG1 的表達之後，對細胞 存活與增生的影響。我們先確定hOGG1 基因在此二細胞株的表達之後，再以siRNA 抑制 hOGG1 於此二細胞株的表達，我們發現經siRNA 抑制hOGG1 表達之後，可增加H2O2 在食道 癌細胞株的細胞毒殺作用，另一方面則可以抑制EGF 所引起的細胞增生反應。我們的體外實 驗顯示，hOGG1 的功能與食道癌的細胞存活與抑制細胞增生有關，藉由這些機轉可能進一步 影響患者治療的存活。The risk to develop esophageal cancer is associated with a variety of environmental and genetic factors. Previously, we have found that individual susceptibility to esophageal cancer in Taiwan was closely related to the consumption of tobacco, alcohol and areca. These factors exerted a synergistic effect on the risk for esophageal cancer. On the other hand, the genetic variation was also found important in determining the individual susceptibility to esophageal cancer. Genetic polymorphisms of the xenobiotic metabolizing enzymes, GSTP1, GSTT1, and CYP1A1, tumor suppressor gene, p53, or DNA repair enzymes, XRCC1 or hOGG1, can significantly influence the risk of esophageal cancer. Given that the DNA damage is the common form induced by the environmental carcinogens and the main contributor to esophageal carcinogenesis, the individual variation in the repairing capacity for damaged DNA would play a important role in determine the tendency for individual carcinogenesis of the esophagus. Therefore, the aim of this study was to investigate whether the genetic alteration of the DNA repair genes, hOGG1, and XRCC1 can modify the individual risk to esophageal cancer. Previously, we have developed the technique of laser capture microdissection (LCM) to obtain pure tumor DNA for analysis. Using this technique, we have alleotyping the hOGG1 on intron 4 and exon 7, where the genetic polymorphisms locates. We also genotyped the patients of esophageal cancer for the hOGG1 Ser 326 Cys genetic polymorphism on intron 7. The expression of the hOGG1 in tumor was also examined by immunohistochemical staining. Totally, we evaluated the status of LOH in tumor from 90 patients. Sixty-seven of them further received immunohistochemical staining for the hOGG1 expression. 204 patients and 266 normal control received genotyping for the hOGG1 polymorphisms. We found that, the risk for the esophageal cancer was enhanced by the presence of the hOGG1 326 Cys allele in the males who did not regularly consume tobacco, alcohol, or areca nut, with ORs(95% CI) being 3.09 (1.22-7.81) for the non-smokers, 2.40 (1.08-5.31) for the non-alcohol drinkers, and 1.86 (0.99-3.49) for the non-areca chewers. Using the technique of Laser Capture Microdissection, we have alleotyping the hOGG1 on intron 4 and exon 7, where the genetic polymorphisms locates. We also found the allelic loss in genetic locus of hOGG1 is a very common episode with 62.2% of cases on the intron 4 and 56.7% of cases on the exon 7. The expression of the hOGG1 in the tumor tissue were also reduced, with 82% of the patients having tumor without expressing or expressing only a very low level of hOGG1 (less than 10% of the tumor cells).The pattern of protein expression and allelic deletion of hOGG1 was not significantly affected by the individual exposure to tobacco, alcohol, or areca nut. However, the deletion status intron 4 and exon 7 of hOGG1 can influence the survival of esophageal cancer after treatment. Those patients who had LOH in the exon 7 of hogg1 have better prognosis than the patients without LOH (p=0.06). This effect looked to be more evident in the cigarette smokers (p<0.05), and alcohol drinkers (p<0.05). The status of lymphnode metastasis was also associated with the deletion of hOGG1 in exon 7 (OR: 2.76; 95% CI: 1.03-7.38). On the contrast, those patient without LOH in the intron 4 of hogg1 have better prognosis after surgery for esophageal cancer (p=0.08). This effect was more prominent in the patients did not smoke cigarette (p<0.05) or drink alcohol (p<0.05). This implies that repair of the oxidative damaged DNA, 8-oxoG, is not only an important mechanism for prevention of neoplasm in the esophagus but also a significant factor affecting the tumor behaviour of esophageal cancer which might act with the factor of environmental exposure.application/pdf163573 bytesapplication/pdfzh-TW國立臺灣大學醫學院外科食道癌基因多型性LOHhOGG1Esophageal cancerPolymorphism[SDGs]SDG3reporthttp://ntur.lib.ntu.edu.tw/bitstream/246246/24520/1/922314B002225.pdf