Guanidinium-Functionalized Flexible Azaproline Transporter for Efficient Intracellular Delivery of Proapoptotic Peptide and PDL1 Antisense Morpholino Oligo in Human Carcinoma Cells <i>In Vitro</i>
作者:Abhishek Gupta、Shalini Gupta、Ujjal Das、Surajit Sinha
DOI:10.1021/acs.bioconjchem.2c00129
日期:2022.5.18
Cell-penetrating peptides (CPPs) are structurally diverse sophisticated tools endowed with high arginine content, amphipathicity, and well-adopted suitable secondary structures. Despite its capability of breaching the lipid barriers, CPP has major limitations such as in vivo metabolic instability, poor bioavailability, and reduced endosomal escape tendency, which are yet to be improved. In this context, we first have introduced a new class of cellular transporter having a guanidinium-functionalized δ-azaproline (δ-azp)-containing peptide where the δ-azp structurally resembles the “proline” amino acid having an additional “N” at the δ-position. This non-natural peptidic backbone was found to impart proteolytic stability, as reported earlier by our group. Herein, we report the synthesis of a flexible azaproline-tetraguanidinium transporter named FAT along with a revised scalable methodology for δ-azp compared to our previously reported procedure. FAT shows a random-coil-like structure as determined by CD spectroscopy, and is hence structurally different from the polyproline PPII helix. Direct translocation is predicted to be the possible mode of the cellular entrance of FAT into CHO cells when the “Bodipy” fluorophore is covalently attached as the cargo. Simultaneously, two other macromolecular therapeutics, e.g., proapoptotic domain peptide (PAD, a 14-mer peptide) and programmed death ligand 1 (PDL1) morpholino (a 25-mer antisense oligo), were successfully conjugated with FAT and delivered into human carcinoma cells, and their efficacy was analyzed by MTT assay and western blot technique, respectively. Having obtained promising results in internalizing different types of cargos, FAT could be envisaged as a potential drug delivery agent as an alternative to natural CPPs for future application.
细胞渗透肽(CPP)是一种结构多样、功能复杂的工具,具有高精氨酸含量、两亲性和良好的次级结构。尽管CPP能够突破脂质屏障,但它存在一些重大局限性,例如体内代谢不稳定、生物利用度低和内体逃逸倾向降低,这些还有待改进。在这种情况下,我们首先引入了一种新型细胞转运蛋白,它具有一个含胍基的δ-氮杂脯氨酸(δ-azp)肽,其中δ-azp在结构上类似于“脯氨酸”氨基酸,在δ位上有一个额外的“N”。正如我们小组之前报道的那样,这种非天然肽基质具有蛋白水解稳定性。在此,我们报道了一种名为FAT的柔性氮杂脯氨酸-四胍转运蛋白的合成,以及与之前报道的方法相比,一种经过修订的δ-azp可扩展方法。通过CD光谱测定,FAT显示出随机卷曲状结构,因此与聚脯氨酸PPII螺旋结构不同。当“Bodipy”荧光团作为货物共价结合时,预计直接转运是FAT进入CHO细胞的可能模式。同时,其他两种大分子治疗剂,例如促凋亡域肽(PAD,一种14肽)和程序性死亡配体1(PDL1)吗啉(一种25�