MiRNA-130a Targets ATG2B and DICER1 to Inhibit Autophagy and Trigger Killing of Chronic Lymphocytic Leukemia Cells

Valentina Kovaleva,Abhilash I Chiramel,Hartmut Döhner,Armin Pscherer,Martina Seiffert,Stephan Stilgenbauer,Ralf Bartenschlager,Rodrigo Mora,Yoon Jung Park,Peter Lichter,Christoph Plass

doi:10.1158/0008-5472.can-11-3671

Abstract

Toxicity and relapses from the immunochemotherapy used to treat chronic lymphocytic leukemia (CLL) prompt continued interest in gentle but effective targeted treatment options for the mainly elderly population suffering from this disease. Here, we report the definition of critical CLL cell survival pathways that can be targeted by ectopic reexpression of the miRNA genes miR-130a and miR-143 which are widely downregulated in CLL. Notably, miR-130a inhibited autophagy by reducing autophagosome formation, an effect mediated by downregulation of the genes ATG2B and DICER1, the latter of which is a major component of the miRNA silencing machinery. In support of the concept of a fundamental connection between miRNA disregulation and altered autophagic flux in this cancer, we showed that RNA interference-mediated knockdown of DICER1 expression was sufficient to reduce autophagy in primary or established cultures of CLL cells. Together, our findings show that miR-130a modulates cell survival programs by regulating autophagic flux, and they define roles for miR-130a and Dicer1 in a regulatory feedback loop that mediates CLL cell survival.

Highlights

B-cell chronic lymphocytic leukemia (CLL) is characterized by the expansion of CD5þ/CD19þ/CD23þ B lymphocytes and shows diverse pathogenic mechanisms and a heterogeneous clinical course [1, 2]
To identify deregulated miRNAs, we carried out miRNA expression profiling on RNA samples of 18 CLL patients and on pooled RNA of Peripheral blood (PB) B lymphocytes of 5 healthy donors by miRNA arrays
Inhibition of endogenous miR-130a by transfection of anti–miR-130a in HEK293T cells increased the luciferase activities of reporter constructs for DICER1 and ATG2B by 10% (P 1⁄4 0.05) and 33% (P 1⁄4 0.03), respectively (Fig. 4C). These results show that miR-130a downregulates DICER1 and ATG2B mRNAs by direct interaction with their 30UTRs and identifies these genes as novel targets for miR-130a in CLL cells

Summary

Introduction

B-cell chronic lymphocytic leukemia (CLL) is characterized by the expansion of CD5þ/CD19þ/CD23þ B lymphocytes and shows diverse pathogenic mechanisms and a heterogeneous clinical course [1, 2]. Prolonged CLL cell survival is induced by autocrine signaling pathways and survival stimuli from the microenvironment [3, 4]. Authors' Affiliations: 1Molecular Genetics; 2Integrative Bioinformatics and Systems Biology; 3Epigenomics and Cancer Risk Factors, German Cancer Research Center; 4Department for Infectious Diseases - Molecular Virology, University of Heidelberg, Heidelberg; 5Internal Medicine III, University of Ulm, Ulm, Germany; and 6Department of Nutritional Science and Food Management, College of Health Science, Ewha Womans University, Seoul, Republic of Korea. Note: Supplementary data for this article are available at Cancer Research Online (http://cancerres.aacrjournals.org/). Mora: Department of Medical Virology, Faculty of Microbiology, University of Costa Rica, San Pedro, Costa Rica

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