基因多型性與肺癌罹患敏感性及疾病 嚴重度之關聯

The Association of Genetic Polymorphisms with Susceptibility to Exposure and Severity of Lung Cancer in Taiwan

施純明(Chuen-Ming Shih)

指導教授 ： 林隆堯

中山醫學大學/醫學院/醫學研究所/博士(2006年)

https://doi.org/10.6834/CSMU.2006.00077

摘要

癌症一直是台灣地區的重要死亡原因；其中肺癌的死亡率在女性與男性分佔癌症死亡率的首位及第二位。肺癌的形成與環境中的污染物 (抽煙、砷中毒、放射線物質、甚至於感染)以及個體的基因 (主要是致癌與抑癌基因、修飾基因與尼古丁代謝基因)都有相關。雖然引起肺癌的直接成因，至今尚未十分確定，但學者研究分析指出，吸煙是引發肺癌的主要外在因素，而遺傳因素則被認為是內在的主要因素。
吸煙被認為是引發肺癌的主要因素，是由於在研究報告中可知，吸煙者得到肺癌的機率是不吸煙者的10至13倍，而且愈年輕開始抽煙、煙齡愈長及煙癮愈大的人，罹患肺癌的機率也隨之增加；而二手煙的吸入也是造成肺癌的一大因素；根據統計，吸煙會使配偶、家人的肺癌罹患率提高至30%以上。中國人習慣以高油溫炒菜或油炸食物，所產生的煙霧可能有致癌物，是導致國內女性罹患肺癌升高的主要因素之一。此外，暴露在污染的空氣中也可能與肺癌的形成有關，台灣的肺癌高死亡率地區集中在高雄、台北、基隆等大都市，這與大都市地區的工業、交通等因素所產生的空氣嚴重污染均有相關。而長期接觸致癌物的職業關係也可能與肺癌的形成有關，長期暴露在等高濃度致癌物如石棉、石油、瀝青、煤焦油、鉻、鎳、鈹、砷、氯乙烯、亞硝酸塩、苯胺染料、放射線和鈾的環境下工作，非常容易誘發肺癌。不當的高脂肪食物攝取也可能有關，意即偏好高脂肪食物的人，其罹患肺腺癌的機率是一般人的11倍。若曾罹患如肺結核、肺炎、慢性支氣管炎、肺氣腫、矽肺、肺部外傷等肺部疾病者，或缺乏維生素Ａ、免疫能力缺乏、內分泌失調、黃麴毒素、病毒感染等因素，都有可能誘發肺癌的形成。
從台灣的肺癌病患之吸煙習慣來分析，大約80%之男性肺癌可歸因於吸煙，但女性肺癌病人85%則無法只以吸煙來解釋。所以由台灣的肺癌流行病學情況而言，無法只以吸煙來說明。腫瘤發生的過程是經過多個階段性的模式發展，其中包括了致癌與抑癌基因出現具體的遺傳學上的缺陷。而這樣的過程可能受到輻射和致癌物環境因素的刺激，也可能是透過慢性炎症或者免疫抑制的影響。根據流行病學資料的證據顯示，慢性發炎可以促進癌症的形成。近年來，許多研究的證據發現，發炎與癌症的形成也有相關，而與發炎有關的細胞激素以其上游調控的基因多型性，越來越受到重視。本論文探討的是，兩個在發炎反應中非常重要的細胞激素，分別是介白質-10 (IL-10)和腫瘤壞死因子-alpha (TNF-alpha)；實驗目的在研究此二者細胞激素啟動子之基因多型性與肺癌病患之間的關聯性，並藉由基因多型性與患者的性別、年齡、癌症種類、癌症時期和存活率的分析，可以幫助瞭解細胞激素與癌症發生的重要性，而在未來的癌症敏感族群鑑定及治療策略上或許可以做不同的思維。

第一部份：介白質-10 (IL-10)基因多型性與肺癌
介白質-10 (IL-10)是一種主要的抗發炎細胞激素，它可經由正常與癌細胞製造與分泌。介白質-10和自體免疫、移植耐受性以及腫瘤的發生都有關連。不同個體之間其介白質-10的分泌濃度會有差異，造成此種差異可能是由於不同的介白質-10啟動子 (promoter)基因多型性的影響所導致。本研究的目的，在於探究介白質-10的基因多型性是否與非小細胞肺癌的罹患敏感性有關，以及是否它與非小細胞肺癌病患的疾病嚴重度及預後有關。我們一共收集了154個肺癌病患與205個正常成人當作對照組。病例組與對照組的IL-10基因多型性測定是以聚合酶連鎖反應與限制酶片段分析基因多型性方法來偵測，並以統計分析方法來判定兩組之間的差異性。
結果發現，肺癌與正常對照組的介白質-10-1082, -819,與-592基因多型性之間都有顯著的統計學上差異。皮耳森卡方分析發現，介白質-10-1082的G基因型，-819的C基因型，以及-592的C基因型在肺癌患者出現的比例較高 (勝算比分別為5.26、1.57與1.59；P值分別為P < 0.0001、P = 0.005與P = 0.005)

第二部份：腫瘤壞死因子-alpha (TNF-alpha)基因多型性與肺癌
腫瘤壞死因子-alpha (TNF-alpha)受到上游啟動子基因多型性的調控與許多發炎和癌症的發生及預後有關連。我們針對調控TNF-alpha啟動子基因-308與-238位置來研究，探討其與非小細胞肺癌的罹患敏感性，與疾病嚴重度以及預後是否有關。我們一共收集了202個肺癌病患與205個正常的成人當作對照組。病例組與對照組的TNF-alpha基因多型性測定是以聚合酶連鎖反應與限制酶片段分析方法來偵測，並且以統計分析方法來判定兩組之間的差異性。
結果發現，肺癌與正常對照組的TNF-alpha-308與-238基因多型性之間都有顯著的統計學上差異 (P<0.0001)。邏輯斯回歸分析發現肺癌病患有比較高的TNF-alpha-308 AA/GA基因型，但在-238 AA/GA基因型的頻率則比較低 (勝算比分別為3.75與0.26；P值分別為P<0.0001與P<0.0001)。而且出現TNF-alpha-308 AA/GA基因型與-238 GG基因型的肺癌病患傾向於屬於較嚴重的病情。

關鍵字

非小細胞肺癌 ； 細胞激素介白質-10 ； 腫瘤壞死因子-alpha ； 基因多型性 ； 啟動子 ； 聚合酶連鎖反應-限制酶片段長度多型性分析 ； 癌症罹病敏感性 ； 預後

並列摘要

Part I: Interleukin-10 polymorphisms and lung cancer
Background
Interleukin-10 (IL-10) is mainly an anti-inflammatory cytokine produced by a number of cells including normal and neoplastic cells and has been implicated in autoimmunity, transplantation tolerance and tumorigenesis. Inter-individual variations in IL-10 production were genetically contributed to polymorphisms within IL-10 promoter region. The aim of this study was to determine whether polymorphisms in the IL-10 gene promoter were involved in predisposing an individual to non-small cell lung cancer (NSCLC).
Methods
A total of 154 patients with NSCLC were recruited into this study, together with 205 age- and gender- matched healthy smokers acting as control subjects. Polymorphisms of sites within the promoter region of IL-10 gene were analyzed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique on genomic DNA isolated from peripheral lymphocytes. The validity of this technique was proven by direct sequencing of PCR products. Statistical analyses were conducted to explore the contribution of polymorphism of IL-10 promoter to the susceptibility to NSCLC.
Results
The distribution frequencies of genotypes of IL-10-1082, -819 and -592 were significantly different between NSCLC patients and controls. Pearson X2 analysis showed that the frequency for IL-10-1082 G allele, IL-10-819 C allele and IL-10-592 C allele was independently higher in NSCLC patient group than that in the control group. Higher odds ratios (ORs) for NSCLC were seen for individuals with G allele of IL-10-1082 [OR = 5.26, 95% CI 2.65-10.4, P < 0.0001], C allele of IL-10-819 [OR = 1.57, 95% CI 1.15–2.16, P =0.005], C allele of IL-10-592 [OR = 1.59, 95% CI 1.15–2.19, P =0.005].
Conclusions
The polymorphisms of IL-10 genes were significantly associated with the occurrence of NSCLC.

Part II: Tumour necrosis factor-α polymorphisms and lung cancer
Background
Genetic polymorphisms in the promoter region of the tumour necrosis factor-α (TNF-α) gene are involved in the regulation of expression levels and have been associated with various inflammatory and malignant conditions. We have investigated two polymorphisms in the promoter region of the TNF-α gene (-308 G/A and -238 G/A) for their role in the susceptibility to and severity of NSCLC, by means of an allelic association study.
Methods
Using a case–control study design, lung cancer patients (n = 202) and appropriate age- and sex-matched controls recruited from the Health Check-Up Unit (n = 205) were subjected to genotype analysis for these polymorphisms, using a high-throughput allelic discrimination method.
Results
Genotype was analyzed using the PCR-RFLP technique with genomic DNA isolated from peripheral blood lymphocytes. Overall, the distribution of the genotype frequencies of TNF-α -308 A/G and -238 A/G were significantly different between the lung cancer patients and the healthy controls, and also different between patients with lung cancers of various stages (P < 0.0001). Logistic regression analysis revealed that higher odds ratios (ORs) for lung cancer were seen for individuals with TNF-α-308 AA/GA genotypes against GG genotype (an OR of 3.75, 95% CI 2.38-5.92, P < 0.0001), and lower ORs were seen for individuals with TNF-α-238 AA/GA genotypes against GG genotype (an OR of 0.26, 95% CI 0.13-0.50, P < 0.0001). The patients carrying a homologous GG or heterologous GA genotype at TNF-308 (P = 0.017), or a homologous AA genotype at TNF-238 (P = 0.001), had a tendency to advanced disease.
Conclusions
A significant association between the 308 G/A and 238 G/A polymorphisms in the promoter region of TNF-α and the susceptibility to lung cancer was demonstrated. Also, these two polymorphisms were associated with the severity of lung cancer. The -308 A allele has a promotive effect for lung cancer development and progression, whereas the -238 A allele has a protective function against lung cancers.

並列關鍵字

Non-small cell lung cancer ； Cytokine ； IL-10 ； TNF-alpha ； Genetic polymorphism ； Promoter ； PCR-RFLP ； Cancer susceptibility ； Prognosis

參考文獻

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