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miR-155 regulative network in FLT3 mutated acute myeloid leukemia
Domenico Salemi1, Giuseppe Cammarata2, Cecilia Agueli1
1Divisione di Ematologia con UTMO, A.O. Ospedali Riuniti Villa Sofia-Cervello, Palermo, Italy.
Background:
Acute myeloid leukemia (AML) represents a heterogeneous disorder with recurrent chromosomal alterations and molecular abnormalities. Among AML with normal karyotype (NK-AML) FLT3 activating mutation, internal tandem duplication (FLT3-ITD), is present in about 30% of patients, conferring unfavorable outcome. Our previous data demonstrated specific up-regulation of miR-155 in FLT3-ITD+ AML. miR-155 is known to be directly implicated in normal hematopoiesis and in some pathologies such as myeloid hyperplasia and acute lymphoblastic leukemia.
Methods And Results:
To investigate about the potential influence of miR-155 de-regulation in FLT3-mutated AML we generated a transcription factors regulatory network and combined this with data from multiple sources that predict miR-155 interactions. From these analyses, we derived a sub-network, called "miR-155 module" that describes functional relationship among miR-155 and transcription factors in FLT3-mutated AML. We found that "miR-155 module" is characterized by the presence of six transcription factors as central hubs: four miR-155 regulators (JUN, RUNX1, FOSb, JUNB) and two targets of miR-155 (SPI1, CEBPB) all known to be "master" genes of myelopoiesis. We found, in FLT3-mutated AML, a significant down-regulation of miR-155 target genes CEBPB and SPI1 and up-regulation of miR-155 regulator genes JUN and RUNX1. We also showed that PKC412-related FLT3 inhibition, in MV4-11 cell line, causes down-regulation of miR-155 and increased level of mRNA and protein of miR-155 target SPI1. We showed in experiments of miR-155 mimic in K562 cell line, a high increase of miR-155 and an inverse correlation with the mRNA levels of its targets SPI1 and CEBPB. Moreover silencing of miR-155 in primary AMLs causes mRNA up-regulation of its target SPI1 and CEBPB.
Conclusion:
Our results suggest that activating mutation of FLT3 in AML can lead, through the induction of JUN, to an increased expression of miR-155, which then causes down-regulation of SPI1 and CEBPB and consequently may causes block of myeloid differentiation.
Insights
Activating FLT3 mutations in acute myeloid leukemia (AML) lead to increased miR-155, which down-regulates SPI1 and CEBPB, potentially blocking myeloid differentiation. This finding offers new insights into AML pathogenesis and therapeutic targets.
Area of Science:
- Molecular Biology
- Oncology
- Genetics
Background:
- Acute myeloid leukemia (AML) is a complex blood cancer with diverse genetic drivers.
- FLT3 internal tandem duplication (FLT3-ITD) mutations are common in normal karyotype AML and associated with poor prognosis.
- Previous research indicated elevated miR-155 levels in FLT3-ITD+ AML patients.
Purpose of the Study:
- To investigate the role of miR-155 dysregulation in FLT3-mutated AML.
- To identify key regulatory interactions within a miR-155-centered network in FLT3-mutated AML.
- To elucidate the impact of miR-155 on myeloid differentiation genes in AML.
Main Methods:
- Construction of a transcription factor regulatory network integrated with miR-155 interaction data.
- Identification of a central
- miR-155 module
- comprising key transcription factors.
- Experimental validation using cell lines (MV4-11, K562) with FLT3 inhibition and miR-155 manipulation (mimic, silencing).
Main Results:
- The
- miR-155 module
- highlighted six central transcription factors, including regulators (JUN, RUNX1) and targets (SPI1, CEBPB) crucial for myelopoiesis.
- FLT3-mutated AML showed decreased expression of miR-155 targets (CEBPB, SPI1) and increased expression of regulators (JUN, RUNX1).
- FLT3 inhibition and miR-155 mimicry reduced target gene expression, while miR-155 silencing increased it, confirming regulatory relationships.
Conclusions:
- Activating FLT3 mutations in AML may induce JUN, leading to increased miR-155 expression.
- This elevated miR-155 down-regulates SPI1 and CEBPB.
- The resulting downregulation of these master myelopoiesis genes likely contributes to blocked myeloid differentiation in AML.
