title: Reversion to an embryonic alternative splicing program enhances leukemia stem cell self-renewal.
abstract: Formative research suggests that a human embryonic stem cell-specific alternative splicing gene regulatory network, which is repressed by Muscleblind-like (MBNL) RNA binding proteins, is involved in cell reprogramming. In this study, RNA sequencing, splice isoform-specific quantitative RT-PCR, lentiviral transduction, and in vivo humanized mouse model studies demonstrated that malignant reprogramming of progenitors into self-renewing blast crisis chronic myeloid leukemia stem cells (BC LSCs) was partially driven by decreased MBNL3. Lentiviral knockdown of MBNL3 resulted in reversion to an embryonic alternative splice isoform program typified by overexpression of CD44 transcript variant 3, containing variant exons 8-10, and BC LSC proliferation. Although isoform-specific lentiviral CD44v3 overexpression enhanced chronic phase chronic myeloid leukemia (CML) progenitor replating capacity, lentiviral shRNA knockdown abrogated these effects. Combined treatment with a humanized pan-CD44 monoclonal antibody and a breakpoint cluster region - ABL proto-oncogene 1, nonreceptor tyrosine kinase (BCR-ABL1) antagonist inhibited LSC maintenance in a niche-dependent manner. In summary, MBNL3 down-regulation-related reversion to an embryonic alternative splicing program, typified by CD44v3 overexpression, represents a previously unidentified mechanism governing malignant progenitor reprogramming in malignant microenvironments and provides a pivotal opportunity for selective BC LSC detection and therapeutic elimination.
authors.affiliation: Division of Regenerative Medicine, Department of Medicine, Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093-0820;
authors.forename: Frida
authors.initials: F
authors.lastname: Holm
authors.affiliation: Division of Regenerative Medicine, Department of Medicine, Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093-0820;
authors.forename: Eva
authors.initials: E
authors.lastname: Hellqvist
authors.affiliation: Division of Regenerative Medicine, Department of Medicine, Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093-0820;
authors.forename: Cayla N
authors.initials: CN
authors.lastname: Mason
authors.affiliation: Division of Regenerative Medicine, Department of Medicine, Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093-0820;
authors.forename: Shawn A
authors.initials: SA
authors.lastname: Ali
authors.affiliation: Division of Regenerative Medicine, Department of Medicine, Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093-0820;
authors.forename: Nathaniel
authors.initials: N
authors.lastname: Delos-Santos
authors.affiliation: Institute of Genomic Medicine, Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093;
authors.forename: Christian L
authors.initials: CL
authors.lastname: Barrett
authors.affiliation: Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, British Columbia, V5Z 1L3, Canada;
authors.forename: Hye-Jung
authors.initials: HJ
authors.lastname: Chun
authors.affiliation: Division of Hematology, Princess Margaret Hospital, Toronto, Ontario, M5G 2M9, Canada;
authors.forename: Mark D
authors.initials: MD
authors.lastname: Minden
authors.affiliation: Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, British Columbia, V5Z 1L3, Canada;
authors.forename: Richard A
authors.initials: RA
authors.lastname: Moore
authors.affiliation: Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, British Columbia, V5Z 1L3, Canada;
authors.forename: Marco A
authors.initials: MA
authors.lastname: Marra
authors.affiliation: Roche Innovation Center Penzberg, Oncology Division, Roche Pharmaceutical Research and Early Development, 82377 Penzberg, Germany.
authors.forename: Valeria
authors.initials: V
authors.lastname: Runza
authors.affiliation: Institute of Genomic Medicine, Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093;
authors.forename: Kelly A
authors.initials: KA
authors.lastname: Frazer
authors.affiliation: Division of Regenerative Medicine, Department of Medicine, Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093-0820;
authors.forename: Anil
authors.initials: A
authors.lastname: Sadarangani
authors.affiliation: Division of Regenerative Medicine, Department of Medicine, Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093-0820; cjamieson@ucsd.edu.
authors.forename: Catriona H M
authors.initials: CH
authors.lastname: Jamieson
mesh_terms: D000328:Adult; D017398:Alternative Splicing / Q000235:genetics*; D000818:Animals; D017209:Apoptosis / Q000235:genetics; D001752:Blast Crisis / Q000235:genetics / Q000473:pathology; D001853:Bone Marrow / Q000473:pathology; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism; D049109:Cell Proliferation; D000066673:Cell Self Renewal / Q000235:genetics*; D002470:Cell Survival; D065150:Cellular Reprogramming / Q000235:genetics; D005260:Female; D016044:Fusion Proteins, bcr-abl / Q000378:metabolism; D015973:Gene Expression Regulation, Leukemic; D055785:Gene Knockdown Techniques; D006410:Hematopoiesis; D000066449:Human Embryonic Stem Cells / Q000378:metabolism*; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000235:genetics* / Q000473:pathology*; D008024:Ligands; D008297:Male; D051379:Mice; D008875:Middle Aged; D009368:Neoplasm Transplantation; D014411:Neoplastic Stem Cells / Q000378:metabolism / Q000473:pathology; D039904:Pluripotent Stem Cells / Q000166:cytology; D000090063:Proto-Oncogene Mas
chemical_list: D015815:Cell Adhesion Molecules; D018960:Hyaluronan Receptors; D008024:Ligands; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D016044:Fusion Proteins, bcr-abl
keywords: CD44v3; MBNL3; RNA splicing; adhesion molecules; self-renewal