title: Single-cell analysis of K562 cells: an imatinib-resistant subpopulation is adherent and has upregulated expression of BCR-ABL mRNA and protein.
abstract: In chronic myeloid leukemia (CML) cells from different stages of maturation may have differential expression of BCR-ABL at both messenger RNA (mRNA) and protein level. However, the significance of such differential expression to clinical disease behavior is unknown. Using the CML-derived, BCR-ABL expressing cell line, K562, distinct plastic-adherent (K562/Adh) and nonadherent (K562/NonAdh) subpopulations were established and then analyzed both as single cells and as bulk cell populations. BCR-ABL mRNA was upregulated in K562/Adh compared with K562/NonAdh cells in both single cell and bulk population analyses (p < 0.0001). Similarly, phosphorylation of BCR protein was upregulated in K562/Adh, compared with K562/NonAdh cells (63.42% vs. 23.1%; p = 0.007), and these two K562 subpopulations were found to express significantly different microRNA species. Furthermore, treatment with the BCR-ABL tyrosine kinase inhibitor, imatinib, reduced cell viability more rapidly in K562/NonAdh compared with K562/Adh cells (p < 0.005) both at single and bulk cell levels. This discovery of an adherent subpopulation of K562 cells with increased BCR-ABL mRNA, increased phosphorylated BCR protein expression, differential microRNA expression, and increased imatinib resistance suggests that a similar subpopulation of cells can also mediate clinical resistance to imatinib during treatment of patients with CML.
authors.affiliation: Institute of Cancer Sciences, Faculty of Medical and Human Sciences, University of Manchester, and Manchester Academic Health Science Centre, Manchester, United Kingdom.
authors.forename: Ehsan Ghayoor
authors.initials: EG
authors.lastname: Karimiani
authors.affiliation: Institute of Cancer Sciences, Faculty of Medical and Human Sciences, University of Manchester, and Manchester Academic Health Science Centre, Manchester, United Kingdom.
authors.forename: Fiona
authors.initials: F
authors.lastname: Marriage
authors.affiliation: Department of Histopathology, Manchester Royal Infirmary, Central Manchester University Hospitals NHS Foundation Trust, Manchester, United Kingdom.
authors.forename: Anita J
authors.initials: AJ
authors.lastname: Merritt
authors.affiliation: Institute of Cancer Sciences, Faculty of Medical and Human Sciences, University of Manchester, and Manchester Academic Health Science Centre, Manchester, United Kingdom; Department of Hematology, Manchester Royal Infirmary, Central Manchester University Hospitals NHS Foundation Trust, Manchester, United Kingdom.
authors.forename: John
authors.initials: J
authors.lastname: Burthem
authors.affiliation: Institute of Cancer Sciences, Faculty of Medical and Human Sciences, University of Manchester, and Manchester Academic Health Science Centre, Manchester, United Kingdom; Department of Hematology, Manchester Royal Infirmary, Central Manchester University Hospitals NHS Foundation Trust, Manchester, United Kingdom. Electronic address: r.byers@manchester.ac.uk.
authors.forename: Richard John
authors.initials: RJ
authors.lastname: Byers
authors.affiliation: Quantitative Molecular Medicine Research Group, Faculty of Medical and Human Sciences, University of Manchester, Manchester, United Kingdom.
authors.forename: Philip J R
authors.initials: PJ
authors.lastname: Day
mesh_terms: D001549:Benzamides / Q000494:pharmacology*; D002448:Cell Adhesion / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D005434:Flow Cytometry; D016044:Fusion Proteins, bcr-abl / Q000235:genetics* / Q000378:metabolism; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D000068877:Imatinib Mesylate; D017404:In Situ Hybridization, Fluorescence; D020014:K562 Cells; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D035683:MicroRNAs / Q000235:genetics; D010766:Phosphorylation / Q000187:drug effects; D010879:Piperazines / Q000494:pharmacology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051562:Proto-Oncogene Proteins c-bcr / Q000235:genetics / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D059010:Single-Cell Analysis / Q000379:methods*; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D001549:Benzamides; D035683:MicroRNAs; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D012333:RNA, Messenger; D000068877:Imatinib Mesylate; D016044:Fusion Proteins, bcr-abl; C496613:BCR protein, human; D051562:Proto-Oncogene Proteins c-bcr