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

Abstract

Background 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.

RUNX1 and RUNX3 Genes Expression Level in Adult Acute Lymphoblastic Leukemia—A Case Control Study

“…The study undertaken by Goyama et al indicated a significant link between the function of the selected genes and leukemic cell survival [ 28 ]. The RUNX1 gene is frequently deregulated in childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL), where the ETV6-RUNX1 translocation causes an overexpression of the RUNX1 gene [ 29 , 30 , 31 ], on the other hand this gene can also be aberrantly expressed in T-ALL cases, where it is reported to be oncogenic in the T-cell lineage and to cause lymphoma in mice [ 32 ]. Despite the similar disease symptoms to childhood leukemia, the adult ALL seems to be a different entity with an altered genetic background and the specific expression pattern is still unclear.…”

Enhancing B-Cell Malignancies—On Repurposing Enhancer Activity towards Cancer

“…Since RUNX1 and CBFA2T3 are upregulated in ETV6-RUNX1 B cell precursor ALL (BCP-ALL) [288], it suggests that RUNX1 and CBFA2T3 may act as a driver loop in BCP-ALL. Indeed, use of a truncated CBFA2T3 protein significantly inhibited RUNX1 activity and reduced BCP-ALL cell proliferation [287].…”

“…RUNX1 also interacts with CBFA2T3 which enhances its transcriptional activity. They act in a self-activation loop, as RUNX1 binds its own promoter and the CBFA2T3 enhancer located 2 kb upstream of the CBFA2T3 promoter [287]. Since RUNX1 and CBFA2T3 are upregulated in ETV6-RUNX1 B cell precursor ALL (BCP-ALL) [288], it suggests that RUNX1 and CBFA2T3 may act as a driver loop in BCP-ALL.…”

Identification of novel PIEZO1::CBFA2T3 and INO80C::SETBP1 fusion genes in an acute myeloid leukemia patient by RNA-seq

“…The CBFA2T3 gene, located on chromosome 16q24.3, is a member of the ETO gene family and an important regulator in hematopoietic progenitor cell proliferation, erythropoiesis, and leukemia stem cell transformation [6-8]. CBFA2T3 encodes a protein that contains four evolutionary conserved nervy homology regions (NHR 1-4), among which the NHR2 domain can interact with hematopoiesis-related transcription factor RUNX1, promoting acute lymphoblastic leukemia proliferation [2].…”