State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China.
Sci China Life Sci. 2011 Feb;54(2):128-38. doi: 10.1007/s11427-010-4124-z. Epub 2011 Feb 14.
To improve the pharmacological profile of tumor necrosis factor alpha (TNF-α), we have synthesized a new PEGylated prodrug, PEG-vcTNF-α, using a cathepsin B-sensitive dipeptide (valine-citrulline, vc) to link branched PEG and TNF-α. PEG-modified TNF-α without the dipeptide linker (PEG-TNF-α) and unconjugated TNF-α were also tested as controls. It was found for the first time that TNF-α released from PEG-vcTNF-α was specifically dependent on the presence of cathepsin B. PEG-vcTNF-α induced higher cytotoxicity and greater apoptosis against L929 murine fibrosarcoma cells than PEG-TNF-α. Reversal of these effects by a cathepsin-B inhibitor confirmed that these effects were mediated by cathepsin B-specific release of TNF-α. In vivo pharmacokinetics studies demonstrated that the plasma stability of PEG-vcTNF-α was significantly increased compared to TNF-α. Finally, the improved anticancer efficacy of PEG-vcTNF-α and the distinct activities among the three formulations confirmed the positive contribution of both PEGylation and the dipeptide linkage to the improved drug-like properties of PEG-vcTNF-α. The results here indicate that linking proteins and PEG via the cathepsin B-sensitive dipeptide may be a promising strategy for developing protein therapeutics.
为了改善肿瘤坏死因子 α（TNF-α）的药理学特性，我们合成了一种新的聚乙二醇化前药 PEG-vcTNF-α，使用组织蛋白酶 B 敏感的二肽（缬氨酸-瓜氨酸，vc）将支化的聚乙二醇和 TNF-α连接起来。还测试了没有二肽接头的聚乙二醇化 TNF-α（PEG-TNF-α）和未缀合的 TNF-α作为对照。这是第一次发现从 PEG-vcTNF-α释放的 TNF-α特异性地依赖于组织蛋白酶 B 的存在。PEG-vcTNF-α对 L929 小鼠纤维肉瘤细胞的细胞毒性和凋亡作用均高于 PEG-TNF-α。组织蛋白酶 B 抑制剂的逆转证实了这些作用是通过组织蛋白酶 B 特异性释放 TNF-α介导的。体内药代动力学研究表明，与 TNF-α相比，PEG-vcTNF-α 的血浆稳定性显著增加。最后，PEG-vcTNF-α 的抗肿瘤功效得到了改善，三种制剂之间的活性明显不同，这证实了聚乙二醇化和二肽连接对 PEG-vcTNF-α改善药物特性的积极贡献。结果表明，通过组织蛋白酶 B 敏感的二肽将蛋白质和聚乙二醇连接起来可能是开发蛋白质治疗药物的一种有前途的策略。
