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MicroRNA Expression in Multiple Myeloma is Associated with Genetic Subtype, Isotype and Prognostic Outcome

ABSTRACT: MicroRNAs are small RNA species that regulate gene expression post-transcriptionally and are aberrantly expressed in many cancers including lymphoma. However, the role of microRNAs in the pathogenesis of multiple myeloma (MM) is poorly understood. We therefore elucidated the complete miRNome of purified tumor (CD138+) cells from 33 patients with MM, 5 patients with monoclonal gammopathy of undetermined significance (MGUS) and 9 disease controls. Unsupervised cluster analysis revealed that MM samples have a distinct microRNA expression profile. The majority of microRNAs aberrantly expressed in MM (109/129) were up-regulated. A comparison of these microRNAs with those aberrantly expressed in other B-cell and T-cell lymphomas revealed a surprising degree of similarity (~40%) suggesting the existence of a common lymphoma microRNA signature. We identified 39 microRNAs associated with the pre-malignant condition MGUS. Twenty-three (59%) of these were also aberrantly expressed in MM suggesting common microRNA expression events in MM progression. MM is characterized by multiple chromosomal abnormalities of varying prognostic significance. We identified specific microRNA signatures associated with the most common IgH translocations (t(4;14) and t(11;14)) and del(13q). Expression levels of these microRNAs were distinct between the genetic subtypes (by cluster analysis) and correctly predicted these abnormalities in >85% of cases using the support vector machine algorithm. Additionally, we identified microRNAs associated with light chain only myeloma, as well as IgG and IgA-type MM. Finally, we identified 32 microRNAs associated with event-free survival (EFS) in MM, ten of which were significant by univariate (logrank) survival analysis. In summary, this work has identified aberrantly expressed microRNAs associated with the diagnosis, pathogenesis and prognosis of MM, data which will prove an invaluable resource for understanding the role of microRNAs in this devastating disease.

ORGANISM(S): Mus musculus Rattus norvegicus Homo sapiens Gallus gallus

PROVIDER: GSE24371 | GEO | 2010/09/29

SECONDARY ACCESSION(S): PRJNA132967

REPOSITORIES: GEO

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Project description:MicroRNAs are small RNA species that regulate gene expression post-transcriptionally and are aberrantly expressed in many cancers including lymphoma. However, the role of microRNAs in the pathogenesis of multiple myeloma (MM) is poorly understood. We therefore elucidated the complete miRNome of purified tumor (CD138+) cells from 33 patients with MM, 5 patients with monoclonal gammopathy of undetermined significance (MGUS) and 9 disease controls. Unsupervised cluster analysis revealed that MM samples have a distinct microRNA expression profile. The majority of microRNAs aberrantly expressed in MM (109/129) were up-regulated. A comparison of these microRNAs with those aberrantly expressed in other B-cell and T-cell lymphomas revealed a surprising degree of similarity (~40%) suggesting the existence of a common lymphoma microRNA signature. We identified 39 microRNAs associated with the pre-malignant condition MGUS. Twenty-three (59%) of these were also aberrantly expressed in MM suggesting common microRNA expression events in MM progression. MM is characterized by multiple chromosomal abnormalities of varying prognostic significance. We identified specific microRNA signatures associated with the most common IgH translocations (t(4;14) and t(11;14)) and del(13q). Expression levels of these microRNAs were distinct between the genetic subtypes (by cluster analysis) and correctly predicted these abnormalities in >85% of cases using the support vector machine algorithm. Additionally, we identified microRNAs associated with light chain only myeloma, as well as IgG and IgA-type MM. Finally, we identified 32 microRNAs associated with event-free survival (EFS) in MM, ten of which were significant by univariate (logrank) survival analysis. In summary, this work has identified aberrantly expressed microRNAs associated with the diagnosis, pathogenesis and prognosis of MM, data which will prove an invaluable resource for understanding the role of microRNAs in this devastating disease. Plasma cells (CD138+) cells were purified from bone marrow samples of 33 patients with MM, 5 patients with monoclonal gammopathy of undetermined significance (MGUS) and 9 disease controls.

Project description:Fibroblasts are a key cellular component of tumour microenvironment, along with other stromal cells playing a critical role in disease initiation and progression (1). In this study, bone marrow fibroblasts deriving from patients with monoclonal gammopathy of undetermined significance (MGUS) or active multiple myeloma (MM) were subjected to global gene expression analysis, in order to identify progression-associated alterations of gene expression. Through immunoselection procedures, primary coltures of bone marrow fibroblasts were established from bone marrow aspirate of 18 patients fullfilling the International Myeloma Working Group diagnostic criteria for MM (n=10) and MGUS (n=8). Differentially expressed genes were investigated through cDNA microarray (21,329 70-mer oligonucleotides; dual-label competitive hybridization), using the reference design as experimental protocol and t-test statistics for identifying differentially expressed genes. A number of genes functionally involved in survival, proliferation, motility, inflammation and angiogenesis were found to be up-regulated in bone marrow fibroblasts from MM patients with respect to MGUS patients. In parallel, several genes were down-regulated in MM fibroblasts. Overall, bone marrow fibroblasts from MM patients show a distinct gene expression pattern that differentiates them from bone marrow fibroblasts of MGUS. The observation of differentially expressed genes indicates an activation state of fibroblasts in MM, which very likely concur to determine a microenvironment supporting disease progression. 1) 1. Kalluri R, Zeisberg M: Fibroblasts in cancer. Nat Rev Cancer 2006; 6: 392 â401. Bone marrow fibroblasts deriving from patients with monoclonal gammopathy of undetermined significance (MGUS) and active multiple myeloma (MM), were provided by A.Vacca, (Department of Biomedical Sciences and Human Oncology, UniversitÃ degli Studi di Bari Aldo Moro, Italy). Briefly, primary coltures of bone marrow fibroblasts were established through immunoselection procedures on aspirates of 18 patients fullfilling the IMWG diagnostic criteria for active MM (n=10) and MGUS (n=8). Total RNA was extracted from each primary culture (test samples), and 1 Î¼g-aliquots of RNA from MGUS samples were pooled to obtain the reference RNA. Linear amplification of mRNA and fluorescent labelling of cDNA targets (Cy5, MM and MGUS test samples; Cy3, reference RNA) were performed by using the Amino Allyl MessageAmp II aRNA Amplification Kit (Ambion), and examined on Micro-CRIBI Human Oligo Array (Operon V2.0) microarrays. Array scanning was carried out using a VersArray ChipReaderÂ® 5Î¼m dual confocal laser scanner with VersArray ChipReader v3.1 analysis software , while row scanner images were analyzed with VersArray Analyzer Software v4.5 (Bio-Rad Laboratories) using media pixel intensities for each spot. Global background was subtracted by biquadratic polynomial approximation, and cross-channel normalization was performed by local regression (LOESS); logarithmic transformation was then performed for each expression level.

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MicroRNA Expression in Multiple Myeloma is Associated with Genetic Subtype, Isotype and Prognostic Outcome

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