Antisense oligonucleotide therapies are important cancer treatments, which can suppress genes in cancer cells that are critical for cell survival. SF3B1 has recently emerged as a promising gene target that encodes a key splicing factor in the SF3B protein complex. Over 10% of cancers have lost one or more copies of the SF3B1 gene, rendering these cancers vulnerable after further suppression. SF3B1 is just one example of a CYCLOPS (Copy-number alterations Yielding Cancer Liabilities Owing to Partial losS) gene, but over 120 additional candidate CYCLOPS genes are known. Antisense oligonucleotide therapies for cancer offer the promise of effective suppression for CYCLOPS genes, but developing these treatments is difficult due to their limited permeability into cells and poor cytosolic stability. Here, we develop an effective approach to suppress CYCLOPS genes by delivering antisense peptide nucleic acids (PNAs) into the cytosol of cancer cells. We achieve efficient cytosolic PNA delivery with the two main nontoxic components of the anthrax toxin: protective antigen (PA) and the 263-residue N-terminal domain of lethal factor (LF_N). Sortase-mediated ligation readily enables the conjugation of PNAs to the C terminus of the LF_N protein. LF_N and PA work together in concert to translocate PNAs into the cytosol of mammalian cells. Antisense SF3B1 PNAs delivered with the LF_N/PA system suppress the SF3B1 gene and decrease cell viability, particularly of cancer cells with partial copy-number loss of SF3B1. Moreover, antisense SF3B1 PNAs delivered with a HER2-binding PA variant selectively target cancer cells that overexpress the HER2 cell receptor, demonstrating receptor-specific targeting of cancer cells. Taken together, our efforts illustrate how PA-mediated delivery of PNAs provides an effective and general approach for delivering antisense PNA therapeutics and for targeting gene dependencies in cancer.

中文翻译：

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通过炭疽介导的肽核酸递送来靶向癌症基因依赖性。

反义寡核苷酸疗法是重要的癌症治疗方法，它可以抑制癌细胞中对细胞生存至关重要的基因。SF3B1最近成为一个有前途的基因靶标，它编码 SF3B 蛋白复合物中的关键剪接因子。超过 10% 的癌症丢失了SF3B1基因的一个或多个拷贝，使得这些癌症在进一步抑制后变得脆弱。SF3B1只是 CYCLOPS（由于部分丢失导致的拷贝数改变导致癌症可能性）基因的一个例子，但已知还有超过 120 个其他候选 CYCLOPS 基因。用于癌症的反义寡核苷酸疗法有望有效抑制 CYCLOPS 基因，但由于它们对细胞的渗透性有限且胞质稳定性差，开发这些疗法很困难。在这里，我们开发了一种通过将反义肽核酸（PNA）递送到癌细胞的细胞质中来抑制 CYCLOPS 基因的有效方法。我们利用炭疽毒素的两种主要无毒成分实现了有效的胞质 PNA 递送：保护性抗原 (PA) 和致死因子的 263 个残基N端结构域 (LF _N )。分选酶介导的连接可以轻松地将 PNA 缀合至 LF _N蛋白的 C 末端。LF _N和 PA 协同工作，将 PNA 易位到哺乳动物细胞的细胞质中。用 LF _N /PA 系统递送的反义SF3B1 PNA抑制SF3B1基因并降低细胞活力，特别是SF3B1部分拷贝数丢失的癌细胞。此外，与 HER2 结合 PA 变体一起递送的反义SF3B1 PNA 选择性靶向过度表达 HER2 细胞受体的癌细胞，证明了癌细胞的受体特异性靶向。总而言之，我们的努力说明了 PA 介导的 PNA 递送如何为递送反义 PNA 疗法和针对癌症中的基因依赖性提供有效且通用的方法。