Bone marrow stromal cells and the upregulation of interleukin-8 production in human T-cell acute lymphoblastic leukemia through the CXCL12/CXCR4 axis and the NF-kappaB and JNK/AP-1 pathways.
BACKGROUND
Cytokines released in the bone marrow and thymic microenvironments play a key role in the growth of T-cell acute lymphoblastic leukemia. Among such cytokines, interleukin-8 is highly expressed in T-cell acute lymphoblastic leukemia cells refractory to chemotherapy. In this study we explored whether bone marrow stromal cells can regulate IL-8 expression in T-cell acute lymphoblastic leukemia and investigated the role of the stromal CXCL12 chemokine in this event. We also investigated the roles of the nuclear factor-kappaB and Jun-N-terminal kinase (JNK)/activating protein (AP)-1 signaling pathways, which contribute to regulate interleukin-8 production in some cells.


METHODS
We analyzed the expression of interleukin-8 in primary cells from ten adult patients with T-cell acute lymphoblastic leukemia when these cells were cultured with bone marrow stromal cells or stimulated with exogenous CXCL12. Interleukin-8 mRNA was analyzed by a colorimetric assay. Cytokine production was assayed by cytometric antibody array and flow cytometry. Nuclear factor-kappaB and JNK/AP-1 activation was investigated by using specific inhibitors of these pathways, immunoblotting, electrophoretic mobility-shift assay and cell transfection assays.


RESULTS
Bone marrow stromal cells upregulated interleukin-8 mRNA in T-cell acute lymphoblastic leukemia cells through the activity of CXCR4, the CXCL12 receptor, as assessed by the use of neutralizing antibodies. Exogenous CXCL12 induced a significant increase in the production of IL-8 mRNA and protein in all T-cell acute lymphoblastic leukemia cases. We showed that CXCL12 activates the nuclear factor-kappaB and JNK/AP-1 pathways, and that these events are required for increased expression of interleukin-8. Furthermore, the nuclear factor-kappaB and AP-1 elements of the interleukin-8 promoter are necessary for both constitutive and CXCL12-induced interleukin-8 expression.


CONCLUSIONS
Interleukin-8 is physiologically regulated by the CXCL12/CXCR4 axis and the nuclear factor-kappaB and JNK/AP-1 pathways are required for interleukin-8 expression in T-cell acute lymphoblastic leukemia. We propose that, by upregulating interleukin-8, the bone marrow microenvironment and the CXCL12/CXCR4 axis may play a role in the pathogenesis of T-cell acute lymphoblastic leukemia.
Scupoli
Maria T
MT
Laboratorio Universitario di Ricerca, Medica (LURM), Policlinico, G.B. Rossi, piazzale L. Scuro 10, 37134 Verona, Italy. mariateresa.scupoli@univr.it
Donadelli
Massimo
M
Cioffi
Federica
F
Rossi
Maria
M
Perbellini
Omar
O
Malpeli
Giorgio
G
Corbioli
Silvia
S
Vinante
Fabrizio
F
Krampera
Mauro
M
Palmieri
Marta
M
Scarpa
Aldo
A
Ariola
Cristina
C
Foà
Robin
R
Pizzolo
Giovanni
G
D000328:Adult; D001854:Bone Marrow Cells / Q000378:metabolism*; D054377:Chemokine CXCL12 / Q000494:pharmacology / Q000502:physiology*; D002986:Clinical Trials as Topic / Q000706:statistics & numerical data; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology; D048031:JNK Mitogen-Activated Protein Kinases / Q000502:physiology*; D019169:Jurkat Cells / Q000187:drug effects / Q000378:metabolism; D015459:Leukemia-Lymphoma, Adult T-Cell / Q000235:genetics / Q000378:metabolism*; D015337:Multicenter Studies as Topic / Q000706:statistics & numerical data; D016328:NF-kappa B / Q000502:physiology*; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D012333:RNA, Messenger / Q000096:biosynthesis; D012334:RNA, Neoplasm / Q000096:biosynthesis; D019718:Receptors, CXCR4 / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000502:physiology; D017154:Stromal Cells / Q000378:metabolism*; D018808:Transcription Factor AP-1 / Q000502:physiology*; D014162:Transfection; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology*
C515255:CXCL12 protein, human; C527276:CXCR4 protein, human; D054377:Chemokine CXCL12; D016209:Interleukin-8; D016328:NF-kappa B; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D019718:Receptors, CXCR4; D011993:Recombinant Fusion Proteins; D018808:Transcription Factor AP-1; D048031:JNK Mitogen-Activated Protein Kinases