Acute myeloid leukemia (AML) cells express and produce C-X-C chemokine receptor 7 (CXCR7). (A) Semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis in AML cell lines. (B) Western blot analysis in AML cell lines. (C) Flow cytometric analysis for CXCR7 in AML cell lines. (D) Flow cytometric analysis after dual staining of CXCR4 and CXCR7 in AML cell lines. (E) Flow cytometric analysis for CXCR7 in CD34⁺ cells obtained from the bone marrow of 5 patients with AML. (F) Immunofluorescence staining after permeabilization for CXCR4 and CXCR7 in U937 cells.

Abbreviations: CXCL12, C-X-C motif ligand 12; GAPDH, glyceraldehyde-3-phosphate dehydrogenase.

C-X-C motif ligand 12 (CXCL12) induces internalization of cell surface C-X-C chemokine receptor 7 (CXCR7) in acute myeloid leukemia (AML) cells. Flow cytometric analysis for cell surface CXCR7 in U937 cells before and after a 2-hr incubation with CXCL12 (200 ng/mL).

Cytokines and hypoxia do not alter C-X-C chemokine receptor 7 (CXCR7) expression in acute myeloid leukemia (AML) cells. (A) AML cell lines were treated with cytokines at various concentrations for up to 72 hr and then subjected to flow cytometric analysis. Representative results (upper panel) and fold-increase of mean fluorescence intensity (MFI) of the experimental cells from that in the controls (no cytokine treatment) (lower panel) from 3 independent experiments, in which U937 cells were treated with 10 µg of each cytokine for 24 hr, are shown. Cells were incubated with 5% CO₂ and 1% O₂, balanced with N₂ gas, at 37℃ for up to 12 hr, and then subjected to flow cytometric analysis (B) and western blot analysis (C).

Abbreviations: IL-6, interleukin 6; GM-SCF, granulocyte-macrophage colony-stimulating factor; TGF-β, tumor growth factor-β; INF-γ, interferon-γ; TNF-α, tumor necrosis factor-α; G-CSF, granulocyte colony-stimulating factor; SCF, stem cell factor; TPO, thrombopoietin; Con, control.

C-X-C chemokine receptor 7 (CXCR7) does not affect migration, serum-deprivation-induced apoptosis, or spontaneous proliferation of acute myeloid leukemia (AML) cells. Using small interfering RNA (siRNA) technology, CXCR4 and CXCR7 were knocked down in MO7e and U937 cells and subsequent biological alterations occurring in the cells were evaluated. (A, B) Transmembrane migration of the cells. Data are expressed as mean±SD of the percentages of migrated cells. (C, D) Data are expressed as mean±SD of the Annexin V-positive apoptotic cells analyzed using flow cytometry. (E, F) Data are expressed as mean±SD of the relative proliferation index at indicated time. All data are from 3 independent experiments.

Knock-down of C-X-C chemokine receptor 7 (CXCR7) upregulates C-X-C motif ligand 12 (CXCL12) expression in acute myeloid leukemia (AML) cells. Using small interfering RNA (siRNA) technology, CXCR4 and CXCR7 were knocked down in U937 cells and then subjected to quantitative reverse transcription polymerase chain reaction (RT-PCR) (A, B) and western blot analysis (C, D). Data are expressed as mean±SD of 3 independent experiments.