title: Transient or long-term silencing of BCR-ABL alone induces cell cycle and proliferation arrest, apoptosis and differentiation.
abstract: BCR-ABL fusion protein, a t(9;22) translocation product is indispensable for generation, maintenance and progression of chronic myeloid leukemia. RNA interference is an approach to silence gene at post-transcriptional level. We show that dsRNA targeted against the translocation region leads to more than 90% inhibition of BCR-ABL mRNA and protein expression levels using K562 as a model. Lack of BCR-ABL leads to cell cycle arrest in G1 phase as observed by decrease in cyclin D1 and increase in p21 and p27 cdk inhibitors mRNA. Apoptosis resistance imparted by BCR-ABL is lost in these cells in caspase-dependent or independent manner. Decrease in Bcl-XL is observed along with decrease in mitochondrial membrane integrity. Transient removal of BCR-ABL expression has a profound effect on proliferation and clonogenic capacity also confirmed by long-term silencing using lentiviral vectors. Interestingly, low level of BCR-ABL message leads to enhanced erythroid differentiation and reduced expression of megakaryocytic markers. Importantly, in six CML patient samples studied, silencing BCR-ABL in the lineage depleted enriched stem cell population leads to a decrease in colony-forming capacity. Thus, long-term silencing of BCR-ABL might prove to be a promising alternative approach in CML patients especially for those who do not respond to any other drug treatment.
authors.affiliation: Haematopoietic Stem Cell Laboratory, London Research Institute, Cancer Research UK, London, UK.
authors.forename: J
authors.initials: J
authors.lastname: Rangatia
authors.forename: D
authors.initials: D
authors.lastname: Bonnet
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D002453:Cell Cycle / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D016044:Fusion Proteins, bcr-abl / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D020868:Gene Silencing; D005822:Genetic Vectors / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D020014:K562 Cells; D007700:Kinetics; D016086:Lentivirus / Q000235:genetics; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000235:genetics*; D012330:RNA, Double-Stranded / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D014410:Tumor Stem Cell Assay / Q000379:methods
chemical_list: D012330:RNA, Double-Stranded; D012333:RNA, Messenger; C406060:abl-bcr fusion protein, human; D016044:Fusion Proteins, bcr-abl