Department of Chemistry, The Scripps Research Institute , La Jolla, California 92037, United States.
J Am Chem Soc. 2013 Sep 18;135(37):13885-91. doi: 10.1021/ja4059525. Epub 2013 Sep 5.
We describe here the development of site-specific antibody-polymer conjugates (APCs) for the selective delivery of small interference RNAs (siRNAs) to target cells. APCs were synthesized in good yields by conjugating an aminooxy-derivatized cationic block copolymer to an anti-HER2 Fab or full-length IgG by means of genetically encoded p-acetyl phenylalanine (pAcF). The APCs all showed binding affinity comparable to that of HER2 as their native counterparts and no significant cellular cytotoxicity. Mutant S202-pAcF Fab and Q389-pAcF IgG polymer conjugates specifically delivered siRNAs to HER2(+) cells and mediated potent gene silencing at both the mRNA and protein levels. However, a mutant A121-pAcF IgG polymer conjugate, despite its high binding affinity to HER2 antigen, did not induce a significant RNA interference response in HER2(+) cells, presumably due to steric interference with antigen binding and internalization. These results highlight the importance of conjugation site on the activity of antibody-polymer-based therapeutics and suggest that such chemically defined APCs may afford a useful targeted delivery platform for siRNAs or other nucleic acid-based therapies.
我们在这里描述了用于将小干扰 RNA（siRNA）选择性递送至靶细胞的靶向抗体-聚合物缀合物（APC）的开发。通过用遗传编码的对乙酰基苯丙氨酸（pAcF）将氨氧基衍生的阳离子嵌段共聚物缀合到抗 HER2 Fab 或全长 IgG 上来，以良好的产率合成了 APC。所有 APC 均表现出与天然抗体相当的结合亲和力，且没有明显的细胞毒性。突变体 S202-pAcF Fab 和 Q389-pAcF IgG 聚合物缀合物可特异性地将 siRNA 递送至 HER2(+)细胞，并在 mRNA 和蛋白质水平上均介导有效的基因沉默。然而，尽管突变体 A121-pAcF IgG 聚合物缀合物对 HER2 抗原具有高结合亲和力，但并未在 HER2(+)细胞中引起明显的 RNA 干扰反应，这可能是由于与抗原结合和内化的空间位阻干扰所致。这些结果强调了抗体-聚合物基治疗剂缀合部位对其活性的重要性，并表明这种化学定义的 APC 可能为 siRNA 或其他核酸基治疗提供有用的靶向递药平台。
