Dihydrofolate Reductase-Mir-30 RNA based Interference for chimeric antibody expression in CHO cells

二氫葉酸還原脢之微型核糖核酸30干擾對CHO細胞表現嵌合型抗體之研究

鄭宏宇(Zheng, Hong Yu)

指導教授 ： 吳夙欽

國立清華大學/生命科學院/生物科技研究所/碩士(2009年)

摘要

中國倉鼠卵巢細胞(Chinese hamster ovary, CHO)與二氫葉酸還原脢(dihydrofolate reductase, dhfr)/Methotrexate (MTX)基因增幅選擇法所建立之穩定細胞株，已廣泛應用於高品質重組藥用蛋白質之產製，例如醫療性抗體。大部份的單株抗體藉由嵌合型或者是擬人化抗體降低免疫反應。本實驗中利用中國倉鼠卵巢細胞表現系統表現抗日本腦炎中和性嵌合型抗體IgG1-2H2和 IgG1-E3.3。干擾載體psd2，被證實可以在dhfr/MTX基因增幅選擇法的製程中，提高CHO/dhfr-（dhfr基因表現缺失的細胞）株穩定純系細胞株表現外源抗體蛋白。
Mir-30 RNA為基礎的sd2干擾載體與一個非專一性對於二氫葉酸還原脢基因干擾載體應用於改善提升穩定增幅細胞株生產的嵌合性抗體IgG1-2H2。結果顯示，在含有MTX的情況下穩定增幅細胞株具有干擾載體psd2和pMir-30 sd2產量約高於未具有干擾載體和非專一性對於二氫葉酸還原脢基因(pscramble) 干擾載體100%。此一方法成功地篩選出高穩定度與高產量的CHO/dhfr-細胞株。利用本研究所提出之RNA干擾載體於dhfr/MTX基因增幅選擇法，可篩選出高穩定性與高產量的穩定增幅細胞株，用以生產抗體或其他生技藥品，對生技製藥產業而言，極富應用性。

關鍵字

中國倉鼠卵巢細胞 ； 二氫葉酸還原脢 ； 嵌合型抗體

並列摘要

Chinese hamster ovary cells (CHO) and dihydrofolate reductase (dhfr)/methotrexate (MTX) gene amplification system are commonly used to generate stable high-producer CHO cell clones in biopharmaceutical industries, such as antibodies, at the present time. Most biopharmaceutical antibody-based products display favorable safety profiles such as chimeric or humanized antibodies. Simulation of bio-pharmaceutical industrial process for antibody production, the expression system using CHO/dhfr- cell as a host cell to express anti-Japanese encephalitis virus (JEV) neutralizing chimeric antibody IgG1-2H2 and IgG1-E3.3. The silencing shRNA vector psd2, which was previously demonstrated the most effective in silencing dhfr RNA transcripts, improved antibody production in dhfr-deficient CHO (CHO/dhfr-¬) cells through dhfr/MTX gene amplification.
Initially, a chimeric mouse-human antibody expression vector was used to express JEV neutralizing chimeric antibodies, IgG1-2H2 and IgG1-E3.3. Then, in addition to psd2, other silencing vectors that were mir-30 based sd2 silencing vector (pmir-30 sd2) and nonspecific of dhfr gene silencing vector (pscramble) were adopted to improve IgG1-2H2 expression in CHO/dhfr- cells. Compare to the average expression level of IgG1-2H2 of CHO/dhfr stable clones, the clones with the silencing vectors pMir-30 sd2 and psd2 were about 100% higher than that with pscramble silencing vector and without silencing vector. Higher level of IgG expression and more stable productivity in MTX-free medium was achieved in amplified stable clones containing psd2 or pMir30-sd2. The method proposed here can be applied to screen high producer cell clones for recombinant antibody or other biologics expression in CHO/dhfr- cells with efficient stable transfection. It can be beneficial for the production of recombinant protein therapeutics in bio-industry.

並列關鍵字

Chinese hamster ovary ； CHO ； dihydrofolate reductase ； dhfr ； chimeric antibody

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