MMSET I acts as an oncoprotein and regulates GLO1 expression in t(4;14) multiple myeloma cells
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ABSTRACT: Multiple myeloma (MM) is characterized by recurrent chromosomal translocations. The translocation t(4;14)(p16;q32) is one of the most common translocation in MMs, affecting 15% of patients, and is associated with very poor prognosis. The histone methyltransferase (HMTase) MMSET is universally overexpressed in t(4;14) MM as a result of the t(4;14) translocation. MMSET is capable of producing 3 major isoforms, the full length MMSET II, short isoforms REIIBP and MMSET I. MMSET II has been suggested to play an important tumorigenic role in t(4;14) MM, but little is yet known about whether and how the MMSET short isoforms contribute to MM tumorigenesis. The aim of this study is to characterize MMSET I roles and determine its downstream targets in t(4;14) MM. In t(4;14) MM cells MMSET I knockdown with shRNAs induced cell apoptosis, reduced colony formation and inhibited tumorigenicity in vivo. We also found MMSET I knockdown decreased GLO1 expression, and ectopic MMSET I increased GLO1 expression, suggesting that MMSET I is an upstream regulator of GLO1. Further analysis indicated that MMSET I bound to GLO1 promoter region and depended on its C-terminus to regulate GLO1 expression. Our preliminary data suggested that MMSET I is an oncoprotein and could regulate GLO1 expression in t(4;14) multiple myeloma cells.
Project description:Multiple myeloma (MM) is characterized by recurrent chromosomal translocations. The multiple myeloma SET domain (MMSET), identified by its fusion to the IgH locus in t(4;14) MM, is universally overexpressed and has been suggested to play an important role in tumorigenicity in t(4;14) MM. In order to identify downstream functional targets of MMSET, we knocked down MMSET expression with shRNAs in KMS11, a t(4;14) MM cell line, and identified differentially expressed genes by gene expression microarray analysis.
Project description:Multiple myeloma (MM) is characterized by recurrent chromosomal translocations. The multiple myeloma SET domain (MMSET), identified by its fusion to the IgH locus in t(4;14) MM, is universally overexpressed and has been suggested to play an important role in tumorigenicity in t(4;14) MM. In order to identify downstream functional targets of MMSET, we knocked down MMSET expression with shRNAs in KMS11, a t(4;14) MM cell line, and identified differentially expressed genes by gene expression microarray analysis. KMS11 cells were treated with shRNAs for 48 h. Total RNA was extracted by using the Qiagen RNeasy Mini kit (Germany). Gene expression was performed using the GeneChip Human Genome U133A Array (Affymetrix) following the manufacturerM-bM-^@M-^Ys instructions. Data analysis was performed using GeneSpring software from Agilent Technologies.
Project description:The MMSET (Multiple Myeloma SET domain) protein is overexpressed in multiple myeloma patients with the translocation t(4;14). Although studies have shown the involvement of MMSET/WHSC1 in development, its mode of action in the pathogenesis of multiple myeloma (MM) is largely unknown. We found that MMSET is a major regulator of chromatin structure and transcription in t(4;14) MM cells. High levels of MMSET correlate with an increase in lysine 36 methylation of histone H3 and a decrease in lysine 27 methylation across the genome, leading to a more open structural state of the chromatin. Loss of MMSET expression alters adhesion properties, suppresses growth and induces apoptosis in MM cells. Consequently, genes affected by high levels of MMSET are implicated in the p53 pathway, cell cycle regulation and integrin signaling. Regulation of many of these genes required functional histone methyl-transferase (HMT) activity of MMSET. These results implicate MMSET as a major epigenetic regulator in t(4;14)+ MM.
Project description:Multiple myeloma (MM) cells undergo metabolic reprogramming in response to a hypoxic and nutrient-deprived bone marrow microenvironment. However, it is unclear whether primary oncogenes in recurrent translocations drive metabolic heterogeneity that can present new vulnerabilities for therapeutic targeting. t(4;14) translocation leads to the universal overexpression of histone methyltransferase MMSET II that promotes plasma cell transformation through a global increase in H3K36me2. We identified PKCα as a novel epigenetic target that contributes to the oncogenic potential of MMSET II. RNA-sequencing of t(4;14) cell lines revealed a significant enrichment in the regulation of metabolic processes by PKCα, and the glycolytic gene, hexokinase 2 (HK2), is transcriptionally regulated by PKCα in a PI3K/Akt-dependent manner. Loss of PKCα displaces mitochondria-bound HK2 and reversed sensitivity towards the glycolytic blocker 3-Bromopyruvate. Additionally, we observed a metabolic shift to a less energetic state through the reduction in oxidative and glycolytic fluxes, resulting in an overall decrease in ATP production. We employed metabolomics and lactate emerged as a differential metabolite associated with PKCα. This conferred PKCα with immunomodulatory drug (IMiDs) resistance in a cereblon-independent manner and could be phenocopied by either overexpression of HK2 or direct supplementation of lactate. Altogether, we revealed novel insights into the epigenetic and metabolism crosstalk in MM and the opportunity for therapeutic intervention that leverages on the distinct metabolic program in t(4;14) myeloma.
Project description:The MMSET (Multiple Myeloma SET domain) protein is overexpressed in multiple myeloma patients with the translocation t(4;14). Although studies have shown the involvement of MMSET/WHSC1 in development, its mode of action in the pathogenesis of multiple myeloma (MM) is largely unknown. We found that MMSET is a major regulator of chromatin structure and transcription in t(4;14) MM cells. High levels of MMSET correlate with an increase in lysine 36 methylation of histone H3 and a decrease in lysine 27 methylation across the genome, leading to a more open structural state of the chromatin. Loss of MMSET expression alters adhesion properties, suppresses growth and induces apoptosis in MM cells. Consequently, genes affected by high levels of MMSET are implicated in the p53 pathway, cell cycle regulation and integrin signaling. Regulation of many of these genes required functional histone methyl-transferase (HMT) activity of MMSET. These results implicate MMSET as a major epigenetic regulator in t(4;14)+ MM. Total RNA was isolated from two different systems: an inducible knock down designed in the 5' region of MMSET. Upon addition of doxycycline we block MMSET expression. The second system we used was a repletion system. By retroviral infection of knock out cells for MMSET we restored the expression of MMSET wild type and two mutants of the protein: one active and one catalytically inactive. Triplicates of each sample were analyzed.
Project description:Recurrent chromosomal translocations are central to the pathogenesis of multiple myeloma (MM), with t(4;14) translocation being the second-most common and associated with poor prognosis. The nuclear receptor-binding SET domain 2 (NSD2) is overexpressed as a result of the translocation and has been suggested to be the primary oncogenic factor in t(4;14) MM. However, the detailed oncogenic mechanism of NSD2 in MM is still not completely understood. To address the relevant pathways downstream of NSD2 that contributes to myelomagenesis, SILAC-based mass-spectrometry analysis was used to determine NSD2-interacting proteins. We identified 74 proteins and in silico analysis showed that one of them, SMARCA2, interacts with NSD2. Comparison of SMARCA2 expression across MM cell lines with different translocation statuses showed that SMARCA2 was highly expressed in t(4;14) MM cells but not in non-t(4;14) MM cells. SMARCA2 knockdown in t(4;14) MM cells showed reduced cell growth and capacity to form colonies. We further investigated how NSD2 and SMARCA2 regulate the expressions of key myeloma genes, such as PRL3 and CCND1. This study reveals a spectrum of NSD2-interacting proteins involved in different biological pathways, indicating the importance of NSD2 in t(4;14) MM. The interaction between NSD2 and SMARCA2 in regulating the expression of CCND1 and PRL3 suggests the potential of SMARCA2 as a novel therapeutic target for t(4;14) MM.
Project description:NSD2, a histone lysine methyltransferase, is overexpressed as a result of the t(4;14) translocation that is associated with 15-20% of multiple myeloma. Earlier studies have indicated that NSD2 may be involved in myelomagenesis and suggested that it may be a target for myeloma therapy. Here we show that NSD2 is required for clonogenic growth, adherence and proliferation on bone marrow stroma, and tumorigenesis of t(4;14)+ but not t(4;14)- myeloma cells, in a methyltransferase activity dependent manner. Furthermore, we found that PHD domains are important for NSD2 cellular activity and biological functions by recruiting it to oncogenic gene loci and driving downstream transcription activation events. These results strengthened the disease link of NSD2 and provided a basis that targeting NSD2 may be a therapeutic strategy in multiple myeloma patients with t(4;14) translocation. Our data also revealed multiple domains in the protein for possible chemical modulation. To elucidate the mechanisms underlying the oncogenic potential of NSD2 in myeloma, we performed microarray analysis on KMS11 parental (PAR), TKO and 8 reconstituted lines. Based on the whole-genome expression profile, the 10 samples clearly fell into 4 clusters – (1) PAR; (2) TKO; (3) WT, WT+MMSET I, 526-1240 and 526-1365; and (4) CDM, CDM+MMSET I, MMSET I and H762Y
Project description:NSD2, a histone lysine methyltransferase, is overexpressed as a result of the t(4;14) translocation that is associated with 15-20% of multiple myeloma. Earlier studies have indicated that NSD2 may be involved in myelomagenesis and suggested that it may be a target for myeloma therapy. Here we show that NSD2 is required for clonogenic growth, adherence and proliferation on bone marrow stroma, and tumorigenesis of t(4;14)+ but not t(4;14)- myeloma cells, in a methyltransferase activity dependent manner. Furthermore, we found that PHD domains are important for NSD2 cellular activity and biological functions by recruiting it to oncogenic gene loci and driving downstream transcription activation events. These results strengthened the disease link of NSD2 and provided a basis that targeting NSD2 may be a therapeutic strategy in multiple myeloma patients with t(4;14) translocation. Our data also revealed multiple domains in the protein for possible chemical modulation. To elucidate the mechanisms underlying the oncogenic potential of NSD2 in myeloma, we performed microarray analysis on KMS11 parental (PAR), TKO and 8 reconstituted lines. Based on the whole-genome expression profile, the 10 samples clearly fell into 4 clusters – (1) PAR; (2) TKO; (3) WT, WT+MMSET I, 526-1240 and 526-1365; and (4) CDM, CDM+MMSET I, MMSET I and H762Y Biological triplicates of cell cultures of indicated lines were harvested in TRIzol (Invitrogen) and characterized by human U133 plus 2.0 Affymetrix GeneChip. The gene expression data was normalized using the Robust Multiarray Averaging (RMA) method and log2 transformed before comparisons.
Project description:Multiple myeloma (MM) is a malignant B cell dyscrasia characterized by the accumulation of clonal plasma cells (PC) within the bone marrow. Epigenetic factors are involved in MM initiation, progression, and occurrence of chemoresistance. Among them EZH2, the Polycomb Repressive Complex 2 (PRC2) catalytic subunit and NSD2 (MMSET), the target oncogene of t(4;14) primary translocation, are both associated with poor prognosis values and contribute to MM disease. In this study, we identified a physical interaction between EZH2 and MMSET in MM. We used MMSET-depleted MM cells and MAK-683, an allosteric inhibitor of EZH2, to disrupt this interaction and understand its implication in MM biology and resistance to anti-MM drugs. Through its interaction with EZH2, MMSET regulates PRC2 nuclear localization in MM cells, promotes a particularly poor prognosis in MM patients, and modulates the expression of tumor-suppressor genes involved in p53 pathway. We also demonstrated that MAK-683 can interfere with this interaction and synergizes with conventional drugs used in MM treatment: Melphalan, an alkylating agent triggering DNA Damage Response (DDR); and Panobinostat, a Histone De-Acetylase (HDAC) inhibitor directedly regulating p53 acetylation and stability.
Project description:Multiple myeloma (MM) is a malignant B cell dyscrasia characterized by the accumulation of clonal plasma cells (PC) within the bone marrow. Epigenetic factors are involved in MM initiation, progression, and occurrence of chemoresistance. Among them EZH2, the Polycomb Repressive Complex 2 (PRC2) catalytic subunit and NSD2 (MMSET), the target oncogene of t(4;14) primary translocation, are both associated with poor prognosis values and contribute to MM disease. In this study, we identified a physical interaction between EZH2 and MMSET in MM. We used MMSET-depleted MM cells and MAK-683, an allosteric inhibitor of EZH2, to disrupt this interaction and understand its implication in MM biology and resistance to anti-MM drugs. Through its interaction with EZH2, MMSET regulates PRC2 nuclear localization in MM cells, promotes a particularly poor prognosis in MM patients, and modulates the expression of tumor-suppressor genes involved in p53 pathway. We also demonstrated that MAK-683 can interfere with this interaction and synergizes with conventional drugs used in MM treatment: Melphalan, an alkylating agent triggering DNA Damage Response (DDR); and Panobinostat, a Histone De-Acetylase (HDAC) inhibitor directedly regulating p53 acetylation and stability.