- 學位論文
將SSEA4抗體作醣基改造以強化其在自然殺手細胞上的抗體依賴性細胞毒殺作用
Glycoengineering of anti-SSEA4 antibody for enhancement of natural killer (NK) cell-mediated antibody dependent cellular cytotoxicity (ADCC)
摘要
在先前的研究，顯示出Globo系列鞘醣脂與多種癌症的進展和腫瘤轉移有關。其中值得注意的是，階段特異性胚胎抗原(stage-specific embryonic antigen, SSEA)-4 在各種人類癌細胞株中，皆有廣泛的表現。因此，我們將SSEA-4 作為發展抗體療法的目標抗原。先利用醣基改造優化成兩種均相化的單株抗體(α2,6-SCT-, α2,6-(Fax)-SCT-chMC813-70)，再分析優化後的均相化抗體對胰臟癌和乳癌細胞的抗體依賴性細胞毒殺(antibody-dependent cellular cytotoxicity, ADCC)作用的效果。結果顯示，優化後的均相化抗體相對於非均相抗體，有較好的效果。接著，我們將均相化抗體應用於篩選初代人類自然殺手細胞，最後透過自然殺手細胞毒性實驗，針對篩選前後的自然殺手細胞，作了其細胞毒殺效果的分析。比較結果顯示，篩選後的自然殺手細胞，對於胰臟癌和乳癌細胞皆有較強的細胞毒殺能力。此結果顯示，醣基均相化的抗體，對於發展抗體療法與自然殺手細胞相關的免疫療法，具有相當的潛力。
並列摘要
According to previous studies, the globo-series glycosphingolipids (GSLs), namely stage-specific embryonic antigen-3 (SSEA-3), SSEA-4 and Globo H are specifically expressed on various cancers and associated with cancer progression and metastasis, and of these three GSLs, SSEA-4 is generally more expressed. Therefore, SSEA-4 is considered to be a better target for developing antibody therapy against GSL-bearing cancers. In an effort to develop therapeutic antibodies to target SSEA4 on cancers, a glycoengineering approach was used to optimize the anti-SSEA4 antibody chMC813-70 to a homogeneous glycoform (α2,6-SCT-chMC813-70 or α2,6-FaxSCT-chMC813-70) with enhanced affinity to FcγRIIIa which is responsible for antibody-dependent cellular cytotoxicity (ADCC). Then, the ADCC effector function of homogeneous anti-SSEA 4 antibody against pancreatic and breast cancers was evaluated. The results showed that the activity of the homogeneous anti-SSEA4 antibodies in inducing ADCC is better than the original heterogeneous antibody. The homogeneous antibody was then used to isolate a subpopulation of primary human natural killer (NK) cells enriched with FcγRIIIa receptor, and the cytotoxicity of the NK cells with or without the selection by homogenous anti-SSEA4 antibody was evaluated. The results showed that the NK cells isolated by the homogenous antibody exhibited higher cytotoxicity against both pancreatic and breast cancer cells, suggesting that the homogeneous antibody is potentially useful for antibody or cell-based immunotherapy.