探討MAGE A4 自體抗體作為腫瘤標記之可行性

- 學位論文 子宮頸癌、卵巢癌一直名列女性癌症死亡十大原因，但在婦科疾病中以子宫肌瘤、子宫肌腺症、子宮內膜異位症最為常見，這些病復發率甚高。臨床上，如果能以血清學的方式檢查，早期診斷出疾病，早期治療，可避免症狀惡化。 SEREX (Serological identification of antigen by recombinant expression cloning)的實驗方法，檢測癌症患者血清中的自體抗體可辨識腫瘤相關抗原(Tumor associated antigen, TAA)，來協助診斷癌症的變化或癒後追蹤的工具。有文獻指出，在癌症形成早期，就可從血清中偵測到高效價的自體抗體。過去本實驗室已製備了數個腫瘤相關抗原，其中p53在105位婦科患者的陽性率達23.81%，而IMP1在55位子宮相關疾病患者中陽性率14.29%。因此，藉由cancer Immunome Database 搜尋與卵巢相關的腫瘤抗原，選擇製備MAGE A4第75至201的胺基酸所表達的蛋白片段，以酵素免疫法偵測90位正常人血清中之自體抗體，發現表現量都很高，再以西方墨點法分析證實血清中有對抗MAGE A4的抗體存在。另外，再選擇在前段第1至74的胺基酸及後段第202至317的胺基酸製備重組蛋白，同樣可偵測到正常人血清含有MAGE A4抗體，顯示MAGE A4 不適合作為腫瘤標記。 Cervical cancer and ovary cancer are the leading cause of death from female cancer in Taiwan. The majority of gynecological diseases, including adenomyosis, myoma, leiomyoma, endometriosis and endometrioma, are always with high recurrences .There is great need to have a Serologic test to detect those of gynecological diseases and use for routine. SEREX method involves the identification of TAAs by screening patient sera, because of autoantibody against TAAs found in patient serum. At early stage of tumorigenesis, high titer of autoantibodies can be detected in patients’ serum. Previously, many recombinant TAAs have been prepared in study of gynecological disease. Autoantibody to p53 was positive rate with 23.81% and IMP1 autoantibody was 14.29%. We select another TAA, MAGE A4, which associated with ovary tumor searching from Cancer immunome database to improve our diagnosis. Autoantibody to MAGE A4 show high level in normal individual with ELISA assay, followed by western blotting, confirmed that autoantibody was in normal individual. Further study, we cloned two recombinant proteins with different location at MAGE A4. Finally, by Western Blotting, autoantibody to MAGE A4 was detected in normal individual. This result suggests that MAGE A4 can not be used as tumor marker in diagnosis. Amanda K. Miles, Balwir Matharoo-Ball, Geng Li Murrium Ahmad, Robert C. Rees (2006). The identification of human tumor antigens: current status and future development. Cancer Immunol Immunother 55, 996-1003. Carlos A. Casiano, Melanie Mediavilla-Varela, and Eng M. Tan (2006). Tumor-associated antigen arrays for the serological diagnosis of cancer. Molecular & Cellular Proteomics 5, 1745-1759. associated with antibodies against the tumor-associated antigen MUC1 and their relationship to risk for ovarian cancer. Cancer Epidemiol Biomarkers Prev 14:1125–1131 Eng M. Tan and Jianying Zhang (2008) Autoantibodies to tumor-associated antigens: reporters from the immune system Immunol Rev. 222: 328–340.