A Double Negative Loop Comprising ETV6/RUNX1 and MIR181A1 Contributes to Differentiation Block in t(12;21)-Positive Acute Lymphoblastic Leukemia

Yung-Li Yang,Sung-Liang Yu,Chien-Yu Lin,Shu-Wha Lin,Ching-Tzu Yen,Dong-Tsamn Lin,Shu-Rung Lin,Chung-Yi Hu,Chen-Hsueh Pai,Hsuan-Yu Chen,Shiann-Tarng Jou

doi:10.1371/journal.pone.0142863

Abstract

Childhood acute lymphoblastic leukemia (ALL) with t(12;21), which results in expression of the ETV6/RUNX1 fusion gene, is the most common chromosomal lesion in precursor-B (pre-B) ALL. We identified 17 microRNAs that were downregulated in ETV6/RUNX1 + compared with ETV6/RUNX1 − clinical samples. Among these microRNAs, miR-181a-1 was the most significantly reduced (by ~75%; P < 0.001). Using chromatin immunoprecipitation, we demonstrated that ETV6/RUNX1 directly binds the regulatory region of MIR181A1, and knockdown of ETV6/RUNX1 increased miR-181a-1 level. We further showed that miR-181a (functional counterpart of miR-181a-1) could target ETV6/RUNX1 and cause a reduction in the level of the oncoprotein ETV6/RUNX1, cell growth arrest, an increase in apoptosis, and induction of cell differentiation in ETV6/RUNX1 + cell line. Moreover, ectopic expression of miR-181a also resulted in decreased CD10 hyperexpression in ETV6/RUNX1 + primary patient samples. Taken together, our results demonstrate that MIR181A1 and ETV6/RUNX1 regulate each other, and we propose that a double negative loop involving MIR181A1 and ETV6/RUNX1 may contribute to ETV6/RUNX1-driven arrest of differentiation in pre-B ALL.

Highlights

The t(12;21) translocation, which fuses ETV6 and RUNX1, is the most common chromosomal alteration in childhood precursor B-cell acute lymphoblastic leukemia (ALL) [1]
Results miR-181a-1 is downregulated in ETV6/RUNX1-positive leukemias, and the regulatory region of MIR181A1 is bound by ETV6/RUNX1 and histone deacetylase-3 (HDAC3)
Seventeen miRNAs were significantly downregulated in ETV6/RUNX1-positive ALL samples (Table 1), and of these, miR-181a-1, which is derived from the 30 arm of precursor hsa-mir-181a-1 (Fig 1A), had the most significant P-value and showed a remarkable 4-fold decrease (Table 1)

Summary

Introduction

The t(12;21) translocation, which fuses ETV6 and RUNX1, is the most common chromosomal alteration in childhood precursor B-cell (pre-B) acute lymphoblastic leukemia (ALL) [1]. The leukemogenic consequences of ETV6/RUNX1 through the aforementioned mechanisms are induction of survival signals and inhibition of cell differentiation by ETV6/RUNX1’s direct modulation of multiple targets such as EPOR, MDM2, and certain miRNA genes [9,10,11]. In addition to the simple negative regulation of target mRNAs by miRNAs, miRNA–target relationships may involve complex feedback and feed-forward loops These loops help to maintain a desired protein inhibition/activation state and often participate in lineage determination in hematopoiesis and lymphomagenesis [12]. Downregulation of two miRNAs i.e., miR-494 and miR-320a, by ETV6/RUNX1 via direct binding to the regulatory regions of miRNA genes has been shown to support ETV6/RUNX1-positive leukemic cell survival through the loss of inhibition of survivin, an anti-apoptotic protein and the target of miR-494 and miR-320a [11]. Our results suggest a mechanism by which ETV6/RUNX1 might exert its preleukemic effect by perturbing the early-stage progression of the B-cell lineage

Materials and Methods

Results

Discussion