Sujet(s)
Résistance aux médicaments antinéoplasiques , Leucémie myéloïde/génétique , microARN/génétique , Antimétabolites antinéoplasiques/pharmacologie , Antimétabolites antinéoplasiques/usage thérapeutique , Azacitidine/pharmacologie , Azacitidine/usage thérapeutique , Lignée cellulaire tumorale , Décitabine/pharmacologie , Décitabine/usage thérapeutique , Régulation de l'expression des gènes dans la leucémie/effets des médicaments et des substances chimiques , Humains , Leucémie myéloïde/traitement médicamenteux , Cellules THP-1Sujet(s)
Protéine-2 homologue de l'activateur de Zeste/génétique , Leucémie myélomonocytaire chronique/traitement médicamenteux , Leucémie myélomonocytaire chronique/génétique , Mitogen-Activated Protein Kinase Kinases/génétique , Inhibiteurs de protéines kinases/pharmacologie , Transduction du signal/génétique , Protéines G ras/génétique , Carcinogenèse/génétique , Lignée cellulaire tumorale , Cellules HL-60 , Humains , Cellules myéloïdes/effets des médicaments et des substances chimiquesRÉSUMÉ
BACKGROUND: Chronic myelomonocytic leukemia (CMML) is an aggressive hematopoietic malignancy that arises from hematopoietic stem and progenitor cells (HSPCs). Patients with CMML are frequently treated with epigenetic therapeutic approaches, in particular the hypomethylating agents (HMAs), azacitidine (Aza) and decitabine (Dec). Although HMAs are believed to mediate their efficacy via re-expression of hypermethylated tumor suppressors, knowledge about relevant HMA targets is scarce. As silencing of tumor-suppressive micro-RNAs (miRs) by promoter hypermethylation is a crucial step in malignant transformation, we asked for a role of miRs in HMA efficacy in CMML. RESULTS: Initially, we performed genome-wide miR-expression profiling in a KrasG12D-induced CMML mouse model. Selected candidates with prominently decreased expression were validated by qPCR in CMML mice and human CMML patients. These experiments revealed the consistent decrease in miR-125a, a miR with previously described tumor-suppressive function in myeloid neoplasias. Furthermore, we show that miR-125a downregulation is caused by hypermethylation of its upstream region and can be reversed by HMA treatment. By employing both lentiviral and CRISPR/Cas9-based miR-125a modification, we demonstrate that HMA-induced miR-125a upregulation indeed contributes to mediating the anti-leukemic effects of these drugs. These data were validated in a clinical context, as miR-125a expression increased after HMA treatment in CMML patients, a phenomenon that was particularly pronounced in cases showing clinical response to these drugs. CONCLUSIONS: Taken together, we report decreased expression of miR-125a in CMML and delineate its relevance as mediator of HMA efficacy within this neoplasia.
Sujet(s)
Antimétabolites antinéoplasiques/usage thérapeutique , Azacitidine/usage thérapeutique , Méthylation de l'ADN/effets des médicaments et des substances chimiques , Décitabine/usage thérapeutique , Régulation de l'expression des gènes/effets des médicaments et des substances chimiques , Leucémie myélomonocytaire chronique/traitement médicamenteux , Leucémie myélomonocytaire chronique/génétique , ARN messager , Animaux , Modèles animaux de maladie humaine , Étude d'association pangénomique , Humains , SourisRÉSUMÉ
Resistance to chemotherapy is one of the primary obstacles in acute myeloid leukemia (AML) therapy. Micro-RNA-23a (miR-23a) is frequently deregulated in AML and has been linked to chemoresistance in solid cancers. We, therefore, studied its role in chemoresistance to cytarabine (AraC), which forms the backbone of all cytostatic AML treatments. Initially, we assessed AraC sensitivity in three AML cell lines following miR-23a overexpression/knockdown using MTT-cell viability and soft-agar colony-formation assays. Overexpression of miR-23a decreased the sensitivity to AraC, whereas its knockdown had the opposite effect. Analysis of clinical data revealed that high miR-23a expression correlated with relapsed/refractory (R/R) AML disease stages, the leukemic stem cell compartment, as well as with inferior overall survival (OS) and event-free survival (EFS) in AraC-treated patients. Mechanistically, we demonstrate that miR-23a targets and downregulates topoisomerase-2-beta (TOP2B), and that TOP2B knockdown mediates AraC chemoresistance as well. Likewise, low TOP2B expression also correlated with R/R-AML disease stages and inferior EFS/OS. In conclusion, we show that increased expression of miR-23a mediates chemoresistance to AraC in AML and that it correlates with an inferior outcome in AraC-treated AML patients. We further demonstrate that miR-23a causes the downregulation of TOP2B, which is likely to mediate its effects on AraC sensitivity.
RÉSUMÉ
RAS-signaling mutations induce the myelomonocytic differentiation and proliferation of hematopoietic stem and progenitor cells. Moreover, they are important players in the development of myeloid neoplasias. RAF kinase inhibitor protein (RKIP) is a negative regulator of RAS-signaling. As RKIP loss has recently been described in RAS-mutated myelomonocytic acute myeloid leukemia, we now aimed to analyze its role in myelomonocytic differentiation and RAS-driven leukemogenesis. Therefore, we initially analyzed RKIP expression during human and murine hematopoietic differentiation and observed that it is high in hematopoietic stem and progenitor cells and lymphoid cells but decreases in cells belonging to the myeloid lineage. By employing short hairpin RNA knockdown experiments in CD34+ umbilical cord blood cells and the undifferentiated acute myeloid leukemia cell line HL-60, we show that RKIP loss is indeed functionally involved in myelomonocytic lineage commitment and drives the myelomonocytic differentiation of hematopoietic stem and progenitor cells. These results could be confirmed in vivo, where Rkip deletion induced a myelomonocytic differentiation bias in mice by amplifying the effects of granulocyte macrophage-colony-stimulating factor. We further show that RKIP is of relevance for RAS-driven myelomonocytic leukemogenesis by demonstrating that Rkip deletion aggravates the development of a myeloproliferative disease in NrasG12D -mutated mice. Mechanistically, we demonstrate that RKIP loss increases the activity of the RAS-MAPK/ERK signaling module. Finally, we prove the clinical relevance of these findings by showing that RKIP loss is a frequent event in chronic myelomonocytic leukemia, and that it co-occurs with RAS-signaling mutations. Taken together, these data establish RKIP as novel player in RAS-driven myeloid leukemogenesis.