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Hyperhaploid Multiple Myeloma

ABSTRACT: Hyperhaploid multiple myeloma is a rare numerical aberration group defined by a range of 24-34 chromosomes which is associated with a poor prognosis. Hyperhaploid samples were sequenced by either exome or targeted panel sequencing. Samples had a median of 13 monosomies (range 12-14), which in general were those not associated with trisomies in hyperdiploid samples. The chromosomes traditionally trisomic in hyperdiploid myeloma were disomic in hyperhaploid myeloma with retention of heterodisomy. We examined the hyperhaploid samples for frequently mutated genes and found that 9/9 (100%) hyperhaploid samples had a mutation in TP53, exceeding the overall rate of mutation in newly diagnosed patients (5.5%), indicating an oncogenic dependency in this group. All samples with TP53 mutation also had monosomy of chromosome 17, indicating bi-allelic inactivation of TP53. As such, this high risk group is part of Double-Hit myeloma. DNA was obtained from either CD138+ cells from the bone marrow of multiple myeloma patients (tumor) or from stem cell harvests from the same patient (control). 100 ng of DNA was fragmented, end-repaired, and adapters ligated using the HyperPlus kit (KAPA Biosystems). After PCR amplification the libraries were hybridized with probes against either the entire exome (MedExome, Nimblegen) or a targeted panel of 140 genes using SeqCap reagents (Nimblegen). Hybridized libraries underwent further amplification before being sequenced on a NextSeq500 (Illumina) using 75 bp paired end reads.

PROVIDER: EGAS00001003203 | EGA |

REPOSITORIES: EGA

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Project description:Currently, multiple myeloma (MM) patients are broadly grouped into a non-hyperdiploid Group (nh-MM), highly enriched for IgH translocations, or into a hyperdiploid Group (h-MM), which is typically characterized by trisomies of some odd-numbered chromosomes. We compared the miRNA expression profiles of these two groups and we identified 16 miRNAs that were downregulated in the h-MM group, relative to the nh-MM group. We found that target genes of the most differentially expressed miRNAs are directly involved in the pathogenesis of MM; specifically, the inhibition of hsa-miR-425, hsa-miR-152 and hsa-miR-24, which are all downregulated in h-MM, leads to the overexpression of CCND1, TACC3, MAFB, FGFR3 and MYC, which are the also the oncogenes upregulated by the most frequent IgH chromosomal translocations occurring in nh-MM. Importantly, we showed that the downregulation of these specific miRNAs and the upregulation of their targets also occur simultaneously in primary cases of h-MM. These data provide further evidence on the unifying role of cyclin C pathways deregulation as the key mechanism involved in the development of both groups of MM. Finally, they establish the importance of miRNA deregulation in the context of MM, thereby opening up the potential for future therapeutic approaches based on this molecular mechanism. miRNA expression profiling: The discovery series was composed of 53 CD138-positive de novo primary cases of Multiple Myeloma, of which 36 were classified as nh-MM and 17 as h-MM. Also included in this first analysis were 7 MM cell lines, six (JJN3, L363, OPM-2, K620, KMS28BM, KMS28PE) representing the nh-MM subtype and one (OH-2) as the model for h-MM. All samples, primary cases and cell lines, were labeled and hybridized in duplicate to the ‘8-pack’ Human miRNA Oligo Microarray G4470A (Agilent Technologies). We differentially expressed miRNA expression between the nh-MM and the h-MM subtypes were identified by standardized bioinformatics methods.

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Hyperhaploid Multiple Myeloma

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