台灣健康人及肝癌病患對多種藥物抗藥性基因多型性變異之探討 Polymorphisms of multidrug resistance gene of healthy population and hepatocellular carcinoma patients in Taiwan
中文摘要
P-醣蛋白(P-glycoprotein)為一廣泛存在於各種組織之跨膜蛋白，其活性直接影響 到人體對多種不同藥(毒)物的感受性，如: digoxin、抗癌藥、人類後天免疫缺損病 毒之抑制劑、rhodamine 等。P-醣蛋白由 1280 個胺基酸所組成，乃為對多種藥物 抗藥性基因(Multidrug Resistant gene, MDR1)之產物。MDR1 基因位於體染色體 7q21，至今已知的多型性變異(polymorphism)至少有 28 個位置。在此 28 個多型 性變異中，具有臨床意義的有C3435T、C1236T、G2677T/A 以及 MDR1 基因驅 動區上游A-41G 及 C-145G 變異。目前的研究結果多集中於西方白人及非洲人。
有關於華人的研究則極其有限。
本研究乃以建立華人MDR1 基因之完整基本資料為目標。以 227 位成年健康台 灣人及169 位肝細胞癌病患為研究對象，利用酵素連鎖反應(Polymerase Chain Reaction; PCR)、限制片段長度多型性(Restriction Fragment Length Polymorphism;
RFLP)及核酸定序法探討 MDR1 基因多型性變異的情況，並與現有其他人種之 研究結果做比較。結果發現，在驅動區上游 -41 及 -145 位置之同合子突變型變 異頻率皆為0.00，與日本學者之研究報告相同。而台灣健康人與肝癌病患 MDR1 基因多型性變異並無明顯的差異，但是發現了台灣肝細胞癌病患C3435T 與 C1236T、G2677T/A 同合子突變型變異的變異連鎖性為 0.95、 0.91，明顯的高於 台灣健康人的0.73、0.70。另外，健康人及肝細胞癌病患同合子突變型 C3435T 變 異頻率分別為0.15 及 0.12，顯著小於已發表研究報告中之法國、沙烏地阿拉伯、
中國和英國人的變異頻率(0.20-0.28) 以及西南亞洲人之變異頻率(0.47)及美國白 人之變異頻率(0.62)。根據我們研究結果顯示，台灣人 MDR1 基因多型性變異的 分佈與其他人種確實有所差異。此外我們也發現了C1236T 無變異加上病毒感染 形成肝細胞癌的危險值是對照組的29.42 倍，而有變異加上病毒感染下卻又比 對照組高出68.74 倍之多，顯示之間具有強烈的關聯性。
英文摘要
P-glycoprotein is a ubiquitous transmembrane protein and exists in many tissues.
The activity of this protein affects the responsiveness of many drugs and toxic substances, such as digoxin, chemotherapeutic drugs, some suppressants for human acquired immunodeficiency virus and rhodamine. P-glycoprotein is a 170- kDa membrane protein, containing 1280 amino acids and it is produced by the multiple drug resistance (MDR1 or ABCB1) gene. The MDR1 gene is located on chromosome 7q21 and consists of 28 exons. To date, 28 single nucleotide polymorphisms (SNPs) in the promoter and exons of the MDR1 gene have been
reported, and it has been demonstrated that the C3435T, C1236T, G2677T/A, A- 41G and C-145G variations are associated with the development of diseases.
Current studies for MDR1 gene are concentrated on Caucasian and African, while those on Chinese are very rare.
The goal of this study is try to pile up some more data and to establish a complete MDR1 gene data base for Chinese. The 227 healthy adults and 169 hepatocellular carcinoma patients from local residents of Taiwan were registered as the study subjects. The methods of polymerase chain reaction, restriction fragment length polymorphism and DNA sequencing were utilized to investigate MDR1
polymorphisms. The results indicate that both frequencies of homozygous variation at -41 and -145 were 0.00, concordant with the results from the study from Japanese. There is no difference between healthy adults and hepatocellular carcinoma patients in the allele frequencies of MDR1 polymorphisms. However, in hepatocellular carcinoma patients, the degree of linkage disequilibrium between C3435T and C1236T and between C3435T and G2677T homozygous variations are higher than that in the healthy control group, (0.95 and 0.91 vs. 0.73 and 0.70, respectively). The frequency of homozygous variation at nucleotide 3435 in the healthy adults and the hepatocellular carcinoma patients is 0.15 and 0.12, respectively, which is lower than that reported for French, Saudi Arabia, China and British populations (with a range between 0.20 to 0.28), as well as lower than that in Southwestern Asians (0.47) and in American Caucasians (0.62). From these experimental results, we can conclude that MDR1 polymorphism distribution is different among ethnic groups. In addition, we found that the C1236T variation in the MDR1 gene is an additive risk factor for hepatocellular carcinoma in viral hepatitis B or C infected patients.
