Dataset Information

Molecular spectrum of BRAF, NRAS and KRAS gene mutations in plasma cell dyscrasias: implication for MEK-ERK pathway activation.

ABSTRACT: Multiple myeloma (MM) is a clinically and genetically heterogeneous plasma cell (PC) malignancy. Whole-exome sequencing has identified therapeutically targetable mutations such as those in the mitogen-activated protein kinase (MAPK) pathway, which are the most prevalent MM mutations. We used deep sequencing to screen 167 representative patients with PC dyscrasias [132 with MM, 24 with primary PC leukemia (pPCL) and 11 with secondary PC leukemia (sPCL)] for mutations in BRAF, NRAS and KRAS, which were respectively found in 12%, 23.9% and 29.3% of cases. Overall, the MAPK pathway was affected in 57.5% of the patients (63.6% of those with sPCL, 59.8% of those with MM, and 41.7% of those with pPCL). The majority of BRAF variants were comparably expressed at transcript level. Additionally, gene expression profiling indicated the MAPK pathway is activated in mutated patients. Finally, we found that vemurafenib inhibition of BRAF activation in mutated U266 cells affected the expression of genes known to be associated with MM. Our data confirm and extend previous published evidence that MAPK pathway activation is recurrent in myeloma; the finding that it is mediated by BRAF mutations in a significant fraction of patients has potentially immediate clinical implications.

SUBMITTER: Lionetti M

PROVIDER: S-EPMC4695180 | biostudies-literature | 2015 Sep

REPOSITORIES: biostudies-literature

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Molecular spectrum of BRAF, NRAS and KRAS gene mutations in plasma cell dyscrasias: implication for MEK-ERK pathway activation.

Lionetti Marta M Barbieri Marzia M Todoerti Katia K Agnelli Luca L Marzorati Simona S Fabris Sonia S Ciceri Gabriella G Galletti Serena S Milesi Giulia G Manzoni Martina M Mazzoni Mara M Greco Angela A Tonon Giovanni G Musto Pellegrino P Baldini Luca L Neri Antonino A

Oncotarget 20150901 27

Multiple myeloma (MM) is a clinically and genetically heterogeneous plasma cell (PC) malignancy. Whole-exome sequencing has identified therapeutically targetable mutations such as those in the mitogen-activated protein kinase (MAPK) pathway, which are the most prevalent MM mutations. We used deep sequencing to screen 167 representative patients with PC dyscrasias [132 with MM, 24 with primary PC leukemia (pPCL) and 11 with secondary PC leukemia (sPCL)] for mutations in BRAF, NRAS and KRAS, which ...[more]

PMID: 26090869

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Project description:Multiple myeloma (MM) is a malignant disorder characterized by the clonal proliferation of plasma cells (PCs) in the bone marrow (BM). The genetic background and clinical course of the disease are largely heterogeneous, and MM pathophysiology ranges from the premalignant condition of monoclonal gammopathy of undetermined significance (MGUS) to smoldering MM, symptomatic MM, and extramedullary MM/plasma cell leukemia (PCL). Recent genome-wide sequencing efforts have provided the rationale for molecularly aimed treatment approaches, identifying mutations that can be specifically targeted, such as those in the mitogen-activated protein kinase (MAPK) pathway, which represent the most prevalent mutations in MM. Among these, mutations affecting BRAF gene, detected in 4-15% of patients, are of potential immediate clinical relevance due to the availability of effective inhibitors of this serine-threonine kinase which are in fact being explored also in myeloma. In this study, we screened by next generation sequencing (NGS) a large and representative series of intramedullary and extramedullary MM patients, including primary and secondary plasma cell leukemia (pPCL and sPCL, respectively), for mutations in BRAF, NRAS and KRAS genes. We evaluated the relationship of identified variants with other clinical and biological features and determined the transcriptional signature associated with MAPK pathway activation in MM. To identify transcriptomic profiles possibly related to BRAF, NRAS and KRAS mutations found in our study, we investigated by Affymetrix microarray technology a large fraction (n=142) of the samples analyzed by NGS, including wild-type patients for all the three genes and cases carrying mutations in at least one of them. Assuming that alterations present in a very limited number of malignant PCs might not appreciably affect gene expression, we chose to arbitrarily establish 20% as the lower variant allele frequency cut-off to perform supervised analyses.

Project description:Multiple myeloma (MM) is a malignant disorder characterized by the clonal proliferation of plasma cells (PCs) in the bone marrow (BM). The genetic background and clinical course of the disease are largely heterogeneous, and MM pathophysiology ranges from the premalignant condition of monoclonal gammopathy of undetermined significance (MGUS) to smoldering MM, symptomatic MM, and extramedullary MM/plasma cell leukemia (PCL). Recent genome-wide sequencing efforts have provided the rationale for molecularly aimed treatment approaches, identifying mutations that can be specifically targeted, such as those in the mitogen-activated protein kinase (MAPK) pathway, which represent the most prevalent mutations in MM. Among these, mutations affecting BRAF gene, detected in 4-15% of patients, are of potential immediate clinical relevance due to the availability of effective inhibitors of this serine-threonine kinase which are in fact being explored also in myeloma. In this study, we screened by next generation sequencing (NGS) a large and representative series of intramedullary and extramedullary MM patients, including primary and secondary plasma cell leukemia (pPCL and sPCL, respectively), for mutations in BRAF, NRAS and KRAS genes. We evaluated the relationship of identified variants with other clinical and biological features and determined the transcriptional signature associated with MAPK pathway activation in MM. To further elucidate the transcriptional programs modulated by BRAF activation in MM, we used the PLX4032 drug to inhibit BRAF activity in U266 human myeloma cell line (HMCL), carrying K601N mutation and showing constitutive activation of MEK/ERK signaling. After confirming its ability to suppress MAPK pathway and myeloma cell proliferation in culture in the U266 cell line, we investigated the specific modulation of gene expression induced by the drug. U266 cells were treated with PLX4032 (30 µM) or DMSO for 12 hours and subjected to gene expression profiling (GEP) analysis by using Affymetrix GeneChip Human Gene 1.0ST arrays.

Dataset Information

Molecular spectrum of BRAF, NRAS and KRAS gene mutations in plasma cell dyscrasias: implication for MEK-ERK pathway activation.

Publications

Molecular spectrum of BRAF, NRAS and KRAS gene mutations in plasma cell dyscrasias: implication for MEK-ERK pathway activation.

Similar Datasets

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