Uckun Fatih M, Qazi Sanjive, Ma Hong, Reaman Gregory H, Mitchell Lloyd G
Children's Center for Cancer and Blood Diseases, Children's Hospital Los Angeles (CHLA), Mailstop 160, 4650 Sunset Boulevard, Smith Research Tower Suite 300-316, Los Angeles, CA 90027, USA.
Integr Biol (Camb). 2015 Feb;7(2):237-49. doi: 10.1039/c4ib00221k.
Our recent studies have demonstrated that the CD22 exon 12 deletion (CD22ΔE12) is a characteristic genetic defect of therapy-refractory clones in pediatric B-precursor acute lymphoblastic leukemia (BPL) and implicated the CD22ΔE12 genetic defect in the aggressive biology of relapsed or therapy-refractory pediatric BPL. The purpose of the present study was to further evaluate the biologic significance of the CD22ΔE12 molecular lesion and determine if it could serve as a molecular target for corrective repair using RNA trans-splicing therapy. We show that both pediatric and adult B-lineage lymphoid malignancies are characterized by a very high incidence of the CD22ΔE12 genetic defect. We provide experimental evidence that the correction of the CD22ΔE12 genetic defect in human CD22ΔE12(+) BPL cells using a rationally designed CD22 RNA trans-splicing molecule (RTM) caused a pronounced reduction of their clonogenicity. The RTM-mediated correction replaced the downstream mutation-rich segment of Intron 12 and remaining segments of the mutant CD22 pre-mRNA with wildtype CD22 exons 10-14, thereby preventing the generation of the cis-spliced aberrant CD22ΔE12 product. The anti-leukemic activity of this RTM against BPL xenograft clones derived from CD22ΔE12(+) leukemia patients provides the preclinical proof-of-concept that correcting the CD22ΔE12 defect with rationally designed CD22 RTMs may provide the foundation for therapeutic innovations that are needed for successful treatment of high-risk and relapsed BPL patients.
我们最近的研究表明，CD22外显子12缺失（CD22ΔE12）是儿童B前体急性淋巴细胞白血病（BPL）中治疗难治性克隆的特征性遗传缺陷，并提示CD22ΔE12遗传缺陷与复发或治疗难治性儿童BPL的侵袭性生物学行为有关。本研究的目的是进一步评估CD22ΔE12分子病变的生物学意义，并确定其是否可作为RNA反式剪接疗法进行纠正修复的分子靶点。我们发现，儿童和成人B系淋巴恶性肿瘤的特征均为CD22ΔE12遗传缺陷的高发生率。我们提供的实验证据表明，使用合理设计的CD22 RNA反式剪接分子（RTM）纠正人CD22ΔE12（+）BPL细胞中的CD22ΔE12遗传缺陷，可显著降低其克隆形成能力。RTM介导的纠正用野生型CD22外显子10-14取代了内含子12的下游富含突变的片段以及突变型CD22前体mRNA的其余片段，从而阻止了顺式剪接异常CD22ΔE12产物的产生。这种RTM对源自CD22ΔE12（+）白血病患者的BPL异种移植克隆的抗白血病活性提供了临床前概念验证，即使用合理设计的CD22 RTM纠正CD22ΔE12缺陷可能为成功治疗高危和复发BPL患者所需的治疗创新奠定基础。
