title: Intraclonal complexity in chronic lymphocytic leukemia: fractions enriched in recently born/divided and older/quiescent cells.
abstract: The failure of chemotherapeutic regimens to eradicate cancers often results from the outgrowth of minor subclones with more dangerous genomic abnormalities or with self-renewing capacity. To explore such intratumor complexities in B-cell chronic lymphocytic leukemia (CLL), we measured B-cell kinetics in vivo by quantifying deuterium ((2)H)-labeled cells as an indicator of a cell that had divided. Separating CLL clones on the basis of reciprocal densities of chemokine (C-X-C motif) receptor 4 (CXCR4) and cluster designation 5 (CD5) revealed that the CXCR4(dim)CD5(bright) (proliferative) fraction contained more (2)H-labeled DNA and hence divided cells than the CXCR4(bright)CD5(dim) (resting) fraction. This enrichment was confirmed by the relative expression of two cell cycle-associated molecules in the same fractions, Ki-67 and minichromosome maintenance protein 6 (MCM6). Comparisons of global gene expression between the CXCR4(dim)CD5(bright) and CXCR4(bright)CD5(dim) fractions indicated higher levels of pro-proliferation and antiapoptotic genes and genes involved in oxidative injury in the proliferative fraction. An extended immunophenotype was also defined, providing a wider range of surface molecules characteristic of each fraction. These intraclonal analyses suggest a model of CLL cell biology in which the leukemic clone contains a spectrum of cells from the proliferative fraction, enriched in recently divided robust cells that are lymphoid tissue emigrants, to the resting fraction enriched in older, less vital cells that need to immigrate to lymphoid tissue or die. The model also suggests several targets preferentially expressed in the two populations amenable for therapeutic attack. Finally, the study lays the groundwork for future analyses that might provide a more robust understanding of the development and clonal evolution of this currently incurable disease.
authors.affiliation: The Feinstein Institute for Medical Research, North Shore-LIJ Health System, Manhasset, New York, United States of America.
authors.forename: Carlo
authors.initials: C
authors.lastname: Calissano
authors.forename: Rajendra N
authors.initials: RN
authors.lastname: Damle
authors.forename: Sonia
authors.initials: S
authors.lastname: Marsilio
authors.forename: Xiao-Jie
authors.initials: XJ
authors.lastname: Yan
authors.forename: Sophia
authors.initials: S
authors.lastname: Yancopoulos
authors.forename: Gregory
authors.initials: G
authors.lastname: Hayes
authors.forename: Claire
authors.initials: C
authors.lastname: Emson
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: Murphy
authors.forename: Marc K
authors.initials: MK
authors.lastname: Hellerstein
authors.forename: Cristina
authors.initials: C
authors.lastname: Sison
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Kaufman
authors.forename: Jonathan E
authors.initials: JE
authors.lastname: Kolitz
authors.forename: Steven L
authors.initials: SL
authors.lastname: Allen
authors.forename: Kanti R
authors.initials: KR
authors.lastname: Rai
authors.forename: Ivana
authors.initials: I
authors.lastname: Ivanovic
authors.forename: Igor M
authors.initials: IM
authors.lastname: Dozmorov
authors.forename: Sergio
authors.initials: S
authors.lastname: Roa
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Scharff
authors.forename: Wentian
authors.initials: W
authors.lastname: Li
authors.forename: Nicholas
authors.initials: N
authors.lastname: Chiorazzi
mesh_terms: D018956:CD5 Antigens / Q000378:metabolism; D002451:Cell Compartmentation; D002455:Cell Division; D049109:Cell Proliferation; D016922:Cellular Senescence; D002999:Clone Cells; D020869:Gene Expression Profiling; D015973:Gene Expression Regulation, Leukemic; D052138:Genes, Neoplasm / Q000235:genetics; D006801:Humans; D016130:Immunophenotyping; D007700:Kinetics; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000235:genetics / Q000473:pathology*; D008954:Models, Biological; D060888:Real-Time Polymerase Chain Reaction; D019718:Receptors, CXCR4 / Q000378:metabolism; D015203:Reproducibility of Results; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D018956:CD5 Antigens; C527276:CXCR4 protein, human; D019718:Receptors, CXCR4