RESUMO
Kindlin-3 (K3)-mediated integrin adhesion controls homing and bone marrow (BM) retention of normal hematopoietic cells. However, the role of K3 in leukemic stem cell (LSC) retention and growth in the remodeled tumor-promoting BM is unclear. We report that loss of K3 in a mouse model of chronic myeloid leukemia (CML) triggers the release of LSCs from the BM into the circulation and impairs their retention, proliferation, and survival in secondary organs, which curbs CML development, progression, and metastatic dissemination. We found de novo expression of cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) on CML-LSCs but not normal hematopoietic stem cells and this enabled us to specifically deplete K3 with a CTLA-4-binding RNA aptamer linked to a K3-siRNA (small interfering RNA) in CTLA-4+ LSCs in vivo, which mobilized LSCs in the BM, induced disease remission, and prolonged survival of mice with CML. Thus, disrupting interactions of LSCs with the BM environment is a promising strategy to halt the disease-inducing and relapse potential of LSCs.
Assuntos
Medula Óssea/metabolismo , Proteínas do Citoesqueleto/deficiência , Leucemia Mieloide/metabolismo , Células-Tronco Neoplásicas/metabolismo , Animais , Antígeno CTLA-4/genética , Antígeno CTLA-4/metabolismo , Movimento Celular , Proteínas do Citoesqueleto/genética , Proteínas de Fusão bcr-abl/genética , Proteínas de Fusão bcr-abl/metabolismo , Células-Tronco Hematopoéticas/citologia , Células-Tronco Hematopoéticas/metabolismo , Humanos , Leucemia Mieloide/genética , Leucemia Mieloide/fisiopatologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Células-Tronco Neoplásicas/citologia , Nicho de Células-Tronco , Microambiente TumoralRESUMO
Anaplastic large cell lymphoma (ALCL) is a rare, aggressive, non-Hodgkin's lymphoma that is characterized by CD30 expression and disease onset in young patients. About half of ALCL patients bear the t(2;5)(p23;q35) translocation, which results in the formation of the nucleophosmin-anaplastic lymphoma tyrosine kinase (NPM-ALK) fusion protein (ALCL ALK(+)). However, little is known about the molecular features and tumour drivers in ALK-negative ALCL (ALCL ALK(-)), which is characterized by a worse prognosis. We found that ALCL ALK(-), in contrast to ALCL ALK(+), lymphomas display high miR-155 expression. Consistent with this, we observed an inverse correlation between miR-155 promoter methylation and miR-155 expression in ALCL. However, no direct effect of the ALK kinase on miR-155 levels was observed. Ago2 immunoprecipitation revealed miR-155 as the most abundant miRNA, and enrichment of target mRNAs C/EBPß and SOCS1. To investigate its function, we over-expressed miR-155 in ALCL ALK(+) cell lines and demonstrated reduced levels of C/EBPß and SOCS1. In murine engraftment models of ALCL ALK(-), we showed that anti-miR-155 mimics are able to reduce tumour growth. This goes hand-in-hand with increased levels of cleaved caspase-3 and high SOCS1 in these tumours, which leads to suppression of STAT3 signalling. Moreover, miR-155 induces IL-22 expression and suppresses the C/EBPß target IL-8. These data suggest that miR-155 can act as a tumour driver in ALCL ALK(-) and blocking miR-155 could be therapeutically relevant. Original miRNA array data are to be found in the supplementary material (Table S1).
Assuntos
Cromossomos Humanos Par 2 , Cromossomos Humanos Par 5 , Linfoma Anaplásico de Células Grandes/genética , MicroRNAs/genética , Translocação Genética , Quinase do Linfoma Anaplásico , Animais , Proteínas Argonautas/genética , Proteínas Argonautas/metabolismo , Proteína beta Intensificadora de Ligação a CCAAT/genética , Proteína beta Intensificadora de Ligação a CCAAT/metabolismo , Estudos de Casos e Controles , Caspase 3/metabolismo , Linhagem Celular Tumoral , Metilação de DNA , Regulação Neoplásica da Expressão Gênica , Terapia Genética/métodos , Humanos , Linfoma Anaplásico de Células Grandes/metabolismo , Linfoma Anaplásico de Células Grandes/patologia , Linfoma Anaplásico de Células Grandes/terapia , Camundongos Endogâmicos NOD , Camundongos SCID , MicroRNAs/metabolismo , Regiões Promotoras Genéticas , Receptores Proteína Tirosina Quinases/deficiência , Receptores Proteína Tirosina Quinases/genética , Fator de Transcrição STAT3/metabolismo , Transdução de Sinais , Proteína 1 Supressora da Sinalização de Citocina , Proteínas Supressoras da Sinalização de Citocina/genética , Proteínas Supressoras da Sinalização de Citocina/metabolismo , Transfecção , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Homing to distinct lymphoid organs enables chronic lymphocytic leukemia (CLL) cells to receive pro-survival and proliferative signals. Cytogenetic aberrations can significantly affect CLL cell compartmentalization. Trisomy 12 (tri12) defines a CLL subgroup with specific clinical features and increased levels of the negative prognostic marker CD49d, the α4-subunit of the integrin VLA-4, which is a key regulator of CLL cell homing to bone marrow (BM). Chemokine-induced inside-out VLA-4 activation, particularly via the CXCL12-CXCR4 axis, increases the arrest of various cell types on VCAM-1 presenting endothelium. Here, we demonstrate that high CD49d expression in tri12 CLL is accompanied by decreased CXCR4 expression. Dissecting functional consequences of these alterations, we observed that tri12 CLL cell homing to murine BM is not affected by CXCR4-CXCL12 blockage using AMD3100 or olaptesed pegol/NOX-A12. In line, CCL21-CCR7 rather than CXCL12-CXCR4 interactions triggered VLA-4-mediated arrests of tri12 CLL cells to VCAM-1 under blood flow conditions. Concordantly, in real-time kinetic analyses we found CCL21 but not CXCL12 being capable to induce inside-out VLA-4 conformational changes in this CLL subgroup. Our results provide novel insights into the peculiar clinico-biological behaviour of tri12 CLL and emphasize its specific chemokine and integrin utilization during pathophysiologically and therapeutically relevant interactions with the microenvironment.