Warren Tiana D, Patel Krishna, Eshleman James R, Ostermeier Marc
Department of Chemical and Biomolecular Engineering , Johns Hopkins University , 3400 N. Charles Street , Baltimore , Maryland 21218 , United States.
ACS Synth Biol. 2019 May 17;8(5):948-954. doi: 10.1021/acssynbio.9b00036. Epub 2019 Apr 23.
One limitation of gene-directed enzyme prodrug therapy (GDEPT) is the difficulty in selectively and efficiently transducing cancer cells with the gene encoding a prodrug-converting enzyme. To circumvent this issue, we sought to move the selectivity from the gene delivery level to the protein level. We developed fusion proteins of the prodrug-activating enzyme yeast cytosine deaminase (yCD) and the oxygen-dependent degradation domain (ODDD) of HIF-1α, a domain that regulates the accumulation of HIF-1α in an oxygen-dependent manner. We called these HOPE fusions for HIF1-α Oxygen-dependent degradation domain/Prodrug-converting Enzyme. The HOPE fusions were designed to selectively accumulate in cells experiencing hypoxia and thus selectively cause conversion of the prodrug 5-fluorocytosine (5-FC) to the chemotherapeutic 5-fluorouracil (5-FU) where oxygen levels are low (e.g., at the center of a tumor). Consistent with our hypothesis, HT1080 fibrosarcoma cells transduced with HOPE fusion genes exhibited increased fusion protein accumulation and increased sensitization to 5-FC in mock-hypoxia.
基因导向酶前药疗法（GDEPT）的一个局限性在于，难以用编码前药转化酶的基因选择性且高效地转导癌细胞。为规避这一问题，我们试图将选择性从基因递送层面转移至蛋白质层面。我们构建了前药激活酶酵母胞嘧啶脱氨酶（yCD）与缺氧诱导因子1α（HIF-1α）的氧依赖性降解结构域（ODDD）的融合蛋白，该结构域以氧依赖性方式调节HIF-1α的积累。我们将这些融合蛋白称为HOPE融合蛋白，即HIF1-α氧依赖性降解结构域/前药转化酶。HOPE融合蛋白旨在选择性地在缺氧细胞中积累，从而在氧含量低的地方（如肿瘤中心）选择性地将前药5-氟胞嘧啶（5-FC）转化为化疗药物5-氟尿嘧啶（5-FU）。与我们的假设一致，用HOPE融合基因转导的HT1080纤维肉瘤细胞在模拟缺氧条件下表现出融合蛋白积累增加以及对5-FC的敏感性增强。
