Analysis of Mantle Cell Lymphoma Patients Reveals Novel Regulatory Circuits Involving MicroRNAs and Their Targets

Abstract 4624

Mantle cell lymphoma (MCL) represents B-cell lymphoma derived from the mantle zone that surrounds normal germinal center follicles. Pathophysiology of this hardly curable disease involves t(11,14)(q13,q32) translocation which leads to upregulation of Cyclin D1(CCND1). Recently, microRNAs were demonstrated to significantly modify MCL pathogenesis (Jian-Jun Zhao et al. 2010) and therapy responsiveness (Jiang et al. 2010). In order to broaden our knowledge of regulatory pathways in MCL we searched for differentially expressed microRNAs and their differentially expressed mRNA targets between MCL samples and control samples. Samples consist of magnetically separated B cells derived from peripheral blood. We used 1) Microarray mRNA hybridization [Affymetrix Human Genome U133 Plus 2.0 Array, N(MCL)=5, N(control)=5] and 2) microRNA profiling [TaqMan® Array Human MicroRNA Card A v2.0 technology, N(MCL)=5, N(control)=5] followed by statistical analysis [limma (Smyth 2005)]. Differentially regulated targets of the deregulated microRNAs were selected from the databases involving both predicted (Betel et al. 2007) or confirmed (Hsu et al. 2010) target mRNAs. Among the most significant upregulated microRNAs (exceeding 10 fold) are miR-9, miR-124 and miR-183. We have found that upregulated miR-9 has confirmed downregulated target gene PRDM1 (PR domain zinc finger protein 1) which plays a role in B cell maturation (Turner et al. 1994) and may act as a tumor suppressor (Pasqualucci et al. 2006). Upregulation of miR-9 and downregulation of its targets was recently demonstrated in Burkitt lymphoma (Onnis A et al. 2010) and Hodgkin lymphoma (Nie K et al. 2008). Two additional upregulated microRNAs, miR-124 and miR-183, yet not associated with lymphomas, have downregulated target gene Integrin beta-1 (CD29) which regulates survival (Fukumori et al. 2003). Among most significant downregulated microRNAs is miR-101 (FC=-7). Downregulated microRNA miR-101 has known oncogene N-Myc (MYCN) as upregulated confirmed target and DNA (cytosine-5)-methyltransferase 3A (DNMT3A) as upregulated target. Overexpression of a well known hematopoietic oncogene MYCN and epigenetic repressor DNMT3A may represent additional pathogenesis-related factors in MCL. Our data support importance of the candidate mechanisms involving microRNAs and their target programs in pathogenesis of MCL. They are currently extended on a larger patient cohort by analyzing expression and functional significance of the candidate microRNAs. (Grants: NT10310-3/2009, MPO FR-TI2/509, NPVII 2B06077, MSM 0021620806, LC 06044, SVV-2011-262507).