title: CD22ΔE12 as a molecular target for corrective repair using RNA trans-splicing: anti-leukemic activity of a rationally designed RNA trans-splicing molecule.
abstract: 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.
authors.affiliation: 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. uckun@usc.edu fmuckun@chla.usc.edu.
authors.forename: Fatih M
authors.initials: FM
authors.lastname: Uckun
authors.forename: Sanjive
authors.initials: S
authors.lastname: Qazi
authors.forename: Hong
authors.initials: H
authors.lastname: Ma
authors.forename: Gregory H
authors.initials: GH
authors.lastname: Reaman
authors.forename: Lloyd G
authors.initials: LG
authors.lastname: Mitchell
mesh_terms: D000328:Adult; D000818:Animals; D001483:Base Sequence; D002648:Child; D005091:Exons; D020869:Gene Expression Profiling; D006801:Humans; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D008969:Molecular Sequence Data; D015452:Precursor B-Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics* / Q000378:metabolism / Q000628:therapy*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012334:RNA, Neoplasm / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D017384:Sequence Deletion; D051918:Sialic Acid Binding Ig-like Lectin 2 / Q000235:genetics*; D052416:Targeted Gene Repair / Q000379:methods*; D020040:Trans-Splicing; D014162:Transfection; D014407:Tumor Cells, Cultured; D014410:Tumor Stem Cell Assay; D023041:Xenograft Model Antitumor Assays
chemical_list: C497867:CD22 protein, human; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D051918:Sialic Acid Binding Ig-like Lectin 2