The chromosomal translocation t(4;11)(q21;q23), a hallmark of an aggressive form of acute lymphoblastic leukemia (ALL), encodes mixed-lineage leukemia (MLL)-AF4 oncogenic chimera that triggers aberrant transcription of genes involved in lymphocyte differentiation, including HOXA9 and MEIS1. The scaffold protein 14-3-3θ, which promotes the binding of MLL-AF4 to the HOXA9 promoter, is a target of MiR-27a, a tumor suppressor in different human leukemia cell types. We herein study the role of MiR-27a in the pathogenesis of t(4;11) ALL. Reverse transcription quantitative PCR (qPCR) reveals that MiR-27a and 14-3-3θ expression is inversely correlated in t(4;11) ALL cell lines; interestingly, MiR-27a relative expression is significantly lower in patients affected by t(4;11) ALL than in patients affected by the less severe t(12;21) leukemia. In t(4;11) leukemia cells, ectopic expression of MiR-27a decreases protein level of 14-3-3θ and of the key transcription factor RUNX1. We show for the first time that MiR-27a also targets AF4 and MLL-AF4; in agreement, MiR-27a overexpression strongly reduces AF4 and MLL-AF4 protein levels in RS4;11 cells. Consequent to AF4 and MLL-AF4 downregulation, MiR-27a overexpression negatively affects transcription of HOXA9 and MEIS1 in different t(4;11) leukemia cell lines. In agreement, we show through chromatin immunoprecipitation experiments that MiR-27a overexpression impairs the binding of MLL-AF4 to the HOXA9 promoter. Lastly, we found that MiR-27a overexpression decreases viability, proliferation, and clonogenicity of t(4;11) cells, whereas it enhances their apoptotic rate. Overall, our study identifies the first microRNAthat strikes in one hit four crucial drivers of blast transformation in t(4;11) leukemia. Therefore, MiR-27a emerges as a new promising therapeutic target for this aggressive and poorly curable form of leukemia.

MiR‐27a downregulates 14‐3‐3θ, RUNX1, AF4, and MLL‐AF4, crucial drivers of blast transformation in t(4;11) leukemia cells / Fioretti, Tiziana; Zanobio, Mariateresa; Raia, Maddalena; Errichiello, Santa; Izzo, Barbara; Cattaneo, Fabio; Ammendola, Rosario; Cevenini, Armando; Esposito, Gabriella. - In: CELL BIOCHEMISTRY AND FUNCTION. - ISSN 0263-6484. - (2022). [10.1002/cbf.3736]

MiR‐27a downregulates 14‐3‐3θ, RUNX1, AF4, and MLL‐AF4, crucial drivers of blast transformation in t(4;11) leukemia cells

Tiziana Fioretti;Mariateresa Zanobio;Maddalena Raia;Santa Errichiello;Barbara Izzo;Fabio Cattaneo;Rosario Ammendola;Armando Cevenini;Gabriella Esposito
2022

Abstract

The chromosomal translocation t(4;11)(q21;q23), a hallmark of an aggressive form of acute lymphoblastic leukemia (ALL), encodes mixed-lineage leukemia (MLL)-AF4 oncogenic chimera that triggers aberrant transcription of genes involved in lymphocyte differentiation, including HOXA9 and MEIS1. The scaffold protein 14-3-3θ, which promotes the binding of MLL-AF4 to the HOXA9 promoter, is a target of MiR-27a, a tumor suppressor in different human leukemia cell types. We herein study the role of MiR-27a in the pathogenesis of t(4;11) ALL. Reverse transcription quantitative PCR (qPCR) reveals that MiR-27a and 14-3-3θ expression is inversely correlated in t(4;11) ALL cell lines; interestingly, MiR-27a relative expression is significantly lower in patients affected by t(4;11) ALL than in patients affected by the less severe t(12;21) leukemia. In t(4;11) leukemia cells, ectopic expression of MiR-27a decreases protein level of 14-3-3θ and of the key transcription factor RUNX1. We show for the first time that MiR-27a also targets AF4 and MLL-AF4; in agreement, MiR-27a overexpression strongly reduces AF4 and MLL-AF4 protein levels in RS4;11 cells. Consequent to AF4 and MLL-AF4 downregulation, MiR-27a overexpression negatively affects transcription of HOXA9 and MEIS1 in different t(4;11) leukemia cell lines. In agreement, we show through chromatin immunoprecipitation experiments that MiR-27a overexpression impairs the binding of MLL-AF4 to the HOXA9 promoter. Lastly, we found that MiR-27a overexpression decreases viability, proliferation, and clonogenicity of t(4;11) cells, whereas it enhances their apoptotic rate. Overall, our study identifies the first microRNAthat strikes in one hit four crucial drivers of blast transformation in t(4;11) leukemia. Therefore, MiR-27a emerges as a new promising therapeutic target for this aggressive and poorly curable form of leukemia.
2022
MiR‐27a downregulates 14‐3‐3θ, RUNX1, AF4, and MLL‐AF4, crucial drivers of blast transformation in t(4;11) leukemia cells / Fioretti, Tiziana; Zanobio, Mariateresa; Raia, Maddalena; Errichiello, Santa; Izzo, Barbara; Cattaneo, Fabio; Ammendola, Rosario; Cevenini, Armando; Esposito, Gabriella. - In: CELL BIOCHEMISTRY AND FUNCTION. - ISSN 0263-6484. - (2022). [10.1002/cbf.3736]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/896036
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