ETV6-RUNX1 and RUNX1 directly regulate RAG1 expression: one more step in the understanding of childhood B-cell acute lymphoblastic leukemia leukemogenesis.

Funder: Société Française de Biochimie et Biologie Moléculaire ; French Research MinistryFunder: Cancéropole Grand Ouest ; Région Bretagne ; Société Française d’HématologieFunder: Ligue Régionale contre le cancer ;ETV6-RUNX1 and RUNX1 directly promote RAG1 expression. ETV6-RUNX1 and RUNX1 preferentially bind to the −1200 bp enhancer of RAG1 and the −80 bp promoter of RAG1 gene respectively, and compete for these bindings. ETV6-RUNX1 and RUNX1 induce an excessive RAG recombinase activity. ETV6-RUNX1 participates directly in two events of the multi-hit ALL leukemogenesis: as an initiating event and as an activator of RAG1 expression

Reduction of RUNX1 transcription factor activity by a CBFA2T3-mimicking peptide: application to B cell precursor acute lymphoblastic leukemia.

Funder: FP7 People: Marie-Curie Actions; doi: http://dx.doi.org/10.13039/100011264; Grant(s): 291851BACKGROUND: B Cell Precursor Acute Lymphoblastic Leukemia (BCP-ALL) is the most common pediatric cancer. Identifying key players involved in proliferation of BCP-ALL cells is crucial to propose new therapeutic targets. Runt Related Transcription Factor 1 (RUNX1) and Core-Binding Factor Runt Domain Alpha Subunit 2 Translocated To 3 (CBFA2T3, ETO2, MTG16) are master regulators of hematopoiesis and are implicated in leukemia. METHODS: We worked with BCP-ALL mononuclear bone marrow patients' cells and BCP-ALL cell lines, and performed Chromatin Immunoprecipitations followed by Sequencing (ChIP-Seq), co-immunoprecipitations (co-IP), proximity ligation assays (PLA), luciferase reporter assays and mouse xenograft models. RESULTS: We demonstrated that CBFA2T3 transcript levels correlate with RUNX1 expression in the pediatric t(12;21) ETV6-RUNX1 BCP-ALL. By ChIP-Seq in BCP-ALL patients' cells and cell lines, we found that RUNX1 is recruited on its promoter and on an enhancer of CBFA2T3 located - 2 kb upstream CBFA2T3 promoter and that, subsequently, the transcription factor RUNX1 drives both RUNX1 and CBFA2T3 expression. We demonstrated that, mechanistically, RUNX1 and CBFA2T3 can be part of the same complex allowing CBFA2T3 to strongly potentiate the activity of the transcription factor RUNX1. Finally, we characterized a CBFA2T3-mimicking peptide that inhibits the interaction between RUNX1 and CBFA2T3, abrogating the activity of this transcription complex and reducing BCP-ALL lymphoblast proliferation. CONCLUSIONS: Altogether, our findings reveal a novel and important activation loop between the transcription regulator CBFA2T3 and the transcription factor RUNX1 that promotes BCP-ALL proliferation, supporting the development of an innovative therapeutic approach based on the NHR2 subdomain of CBFA2T3 protein

Hypoxia regulates CD9 expression and dissemination of B lymphoblasts

International audienceAcute lymphoblastic leukemias (ALL) are the most frequent cancer in children and derive most often from B-cell precursors. Current survival rates roughly reach 90% at 10 years from diagnosis. However, 15-20% of children still relapse with a significant risk of death. Our previous work showed that the transmembrane protein CD9 plays a major role in lymphoblasts migration into sanctuary sites, especially in testis, through the activation of RAC1 signaling upon blasts stimulation with C-X-C chemokine ligand 12 (CXCL12). Here, we identified common factors shared by the bone marrow and extramedullary niches which could upregulate CD9 expression and function. We found that low oxygen levels enhance CD9 expression both at mRNA and protein levels. We further determined that Hypoxia Inducible Factor 1 alpha (HIF1 alpha), the master transcription factor involved in hypoxia response, binds directly CD9 promoter and induce CD9 transcription. We also showed that CD9 protein is crucial for leukemic cell adhesion and migration at low oxygen levels, possibly through its action on RAC1 signaling. Mouse xenograft experiments indicate that HIF1 alpha signaling pathway promotes ALL cells engraftment in a CD9-dependent manner. The present work increments our understanding of CD9 implication in ALL pathogenesis

COVID-19 and acute lymphoblastic leukemias of children and adolescents: First recommendations of the Leukemia committee of the French Society for the fight against Cancers and Leukemias in children and adolescents (SFCE)

International audienceSince the emergence of the SARS-CoV-2 infection many recommendations have been made. However the very nature of acute lymphoblastic leukemias and their treatment in children and adolescents led the Leukemia Committee of the French Society for the fight against cancers and leukemias in children and adolescents (SFCE) to propose more specific recommendations even if data for this population are still scarce. They may have to evolve according to the rapid evolution of knowledge on COVID-19

Impact of the First Wave of COVID-19 on Pediatric Oncology and Hematology: A Report from the French Society of Pediatric Oncology

Data regarding coronavirus disease 2019 (COVID-19) description are still limited in pediatric oncology. The French society of pediatric oncology (SFCE) initiated a study to better describe COVID-19 in patients followed in French pediatric oncology and hematology wards. All patients diagnosed with COVID-19 and followed in a SFCE center were enrolled. Data from medical records were analyzed for all patients enrolled up to the end of May 2020. Data were available for 37 patients. Thirty-one were children under 18 years of age. Nineteen patients were female. Seventeen patients had a solid tumor, 16 had a hematological malignancy and four recently underwent hematopoietic stem cell transplantation (HSCT) for non-oncological conditions. Twenty-eight patients presented symptoms, most often with fever, cough, rhinorrhea and asthenia. Ground-glass opacities were the most frequent radiological finding with abnormalities mostly bilateral and peripherally distributed. Twenty-four patients received chemotherapy a month prior to COVID-19 diagnosis. Most patients did not require hospitalization. Three patients required oxygen at the time of diagnosis. In total, five patients were admitted in an intensive care unit because of COVID-19 and one died from the disease. Children and young adults treated for a cancer and/or with a HSCT may be at risk for severe COVID-19 and should be closely monitored

Early impact of severe acute respiratory syndrome coronavirus 2 on pediatric clinical research : a Pan-European and Canadian snapshot in time

Objective To capture the early effects of the coronavirus disease 2019 (COVID-19) pandemic on pediatric clinical research. Study design Pediatric clinical research networks from 20 countries and 50 of their affiliated research sites completed two surveys over one month from early May to early June 2020. Networks liaised with their affiliated sites and contributed to the interpretation of results through pan-European group discussions. Based on first detection dates of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), countries formed 1 early detecting and 1 late detecting cluster. We tested the hypothesis that this clustering influenced clinical research. Results Research sites were first impacted by the pandemic in mid-March 2020 (March 16 +/- 10 days, the same date as lockdown initiation; P = .99). From first impact up until early June, site initiation and feasibility analysis processes were affected for >50% of the sites. Staff were redirected to COVID-19 research for 44% of the sites, and 75.5% of sites were involved in pediatric COVID-19 research (only 6.3% reported COVID-19 cases in their other pediatric trials). Mitigation strategies were used differently between the early and late detecting country clusters and between countries with and without a pediatric COVID-19 research taskforce. Positive effects include the development of teleworking capacities. Conclusions Through this collaborative effort from pediatric research networks, we found that pediatric trials were affected and conducted with a range of unequally applied mitigations across countries during the pandemic. The global impact might be greater than captured. In a context where clinical research is increasingly multinational, this report reveals the importance of collaboration between national networks