Efficient delivery of oligonucleotides still remains a challenge in the field of oligonucleotide based therapy. Peptide nucleic acid (PNA), a DNA analogue that is typically synthesized by solid phase peptide chemistry, has been conjugated to a variety of cell penetrating peptides (CPP) as a means of improving its cellular uptake. These CPPs typically deliver their cargoes into cells by an endosomal-dependent mechanism resulting in lower bioavailability of the cargo. Herein, we designed and synthesized PNA–peptide conjugates as splice switching oligonucleotides (SSO) targeting the Mnk2 gene, a therapeutic target in cancer. In humans, the MKNK2 gene, is alternatively spliced, generating isoforms with opposite biological activities: Mnk2a and Mnk2b. It was found that the Mnk2a isoform is down-regulated in breast, lung, brain, and colon tumors and is a tumor suppressor, whereas MnK2b is oncogenic. We have designed and synthesized PNAs that were conjugated to either of the following peptides: a nuclear localization sequence (NLS) or a cytosol localizing internalization peptide (CLIP6). CLIP6-PNA demonstrates effective cellular uptake and exclusively employs a nonendosomal mechanism to cross the cellular membranes of glioblastoma cells (U87). Simple incubation of PNA–peptide conjugates in human glioblastoma cells up-regulates the Mnk2a isoform leading to cancer cell death.

中文翻译：

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CLIP6-PNA肽缀合物：剪接开关寡核苷酸的非内体传递。

在基于寡核苷酸的治疗领域中，有效递送寡核苷酸仍然是一个挑战。肽核酸（PNA）是一种通常通过固相肽化学合成的DNA类似物，已与多种细胞穿透肽（CPP）偶联，以改善其细胞吸收能力。这些CPP通常通过内体依赖性机制将其货物递送到细胞中，从而导致货物的生物利用度降低。在本文中，我们设计并合成了PNA-肽共轭物，将其作为靶向Mnk2基因（癌症的治疗靶标）的剪接转换寡核苷酸（SSO）。在人类中，MKNK2基因被选择性剪接，产生具有相反生物学活性的同工型：Mnk2a和Mnk2b。发现Mnk2a亚型在乳腺，肺，脑，和结肠肿瘤，并且是肿瘤抑制因子，而MnK2b具有致癌性。我们设计并合成了与以下任何一种肽缀合的PNA：核定位序列（NLS）或胞浆定位内化肽（CLIP6）。CLIP6-PNA证明有效的细胞摄取，并专门采用非内体机制穿越胶质母细胞瘤细胞（U87）的细胞膜。在人胶质母细胞瘤细胞中简单孵育PNA-肽结合物会上调Mnk2a亚型，导致癌细胞死亡。CLIP6-PNA证明有效的细胞摄取，并专门采用非内体机制穿越胶质母细胞瘤细胞（U87）的细胞膜。在人胶质母细胞瘤细胞中简单孵育PNA-肽结合物会上调Mnk2a亚型，导致癌细胞死亡。CLIP6-PNA证明有效的细胞摄取，并专门采用非内体机制穿越胶质母细胞瘤细胞（U87）的细胞膜。在人胶质母细胞瘤细胞中简单孵育PNA-肽结合物会上调Mnk2a亚型，导致癌细胞死亡。