The Fusion Gene Landscape in Multiple Myeloma, with Clinical Impact

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 835-835 ◽  
Author(s):  
Alice Cleynen ◽  
Raphaël Szalat ◽  
Mehmet Kemal Samur ◽  
Giovanni Parmigiani ◽  
Nikhil C. Munshi ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Genomic Instability ◽  
Cell Lines ◽  
Conflicts Of Interest ◽  
Fusion Gene ◽  
Expression Profiles ◽  
Negative Regulation ◽  
Functional Enrichment ◽  
Fusion Product ◽  
Fusion Genes

Abstract Background: Gene fusions play an important role in aberrant cellular biology as well as development and progression of cancer. Expression of fusion genes such as PML-RAR drives the transformation in APL and provides important targets for therapy. However, in multiple Myeloma (MM), a heterogeneous disease characterized by genomic instability, frequent gains and losses of DNA, and a diverse mutational landscape, only the well characterized MMSET-IGH fusion product has been reported. Here we investigate the fusion gene landscape in multiple myeloma, and its possible impact on survival. Method: Deep RNA-Seq was performed on purified MM cells from 430 newly-diagnosed MM patients, 20 normal individuals and 71 cell-lines; data were analyzed for gene expression profiles, long-non coding RNA signatures, and both novel and known fusion genes using two common algorithms: TopHat and MapSplice. MM characteristics, cytogenetic and FISH as well as clinical survival outcomes were also analyzed and correlated with genomic data. Results: After filtering candidate fusions linking genes belonging to the same family, we identified 416 different candidates in myeloma patients, 40 % of which identified either IGH or Kappa as a partner. IGH fusion partners included the previously described and validated WHSC1 and B2M genes, as well as over 50 new candidates, while more than 70 different partners were found to be fused with Kappa. These genes exhibit functional enrichment of positive regulators of the cytokine-mediated signaling pathway, negative regulation of myeloid cell differentiation, negative regulation of interleukin-6 production, as well as others. 31% of patients presented no fusions, and another 32% presented a single fusion event. The other 37% presented at least 2 fusion candidates, with up to 27 different candidates. Similar patterns were observed in cell-lines, with 196 unique candidates identified, only 16% of which involving IGH or kappa. However, all partners were found in at least one patient as well. Only 12% of cell-lines exhibited no fusion, and another 14% presented only one fusion. On average, 3 fusions were identified per cell-line, with a maximum of 10. Validation of some these fusion genes is required to understand their functional role. Importantly, although having IgH-or kappa-related fusions did not affect patient outcome by themselves, patients with high numbers of fusion candidates had worse event-free survival. Conclusion: Our data describes a diverse and rich fusion gene landscape in Multiple Myeloma. Similar to mutational profiles, there is no predominant fusion gene driving the disease process. Association of poor prognosis with a higher number of fusions may indicate that genomic instability plays an important role in the biology of Multiple Myeloma. Disclosures No relevant conflicts of interest to declare.

NEDD4-1 Modulates the Resistance of Multiple Myeloma to Bortezomib

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2068-2068
Author(s):  
Xi Huang ◽  
Enfan Zhang ◽  
Xing Guo ◽  
Jing Chen ◽  
Xuanru Lin ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Lines ◽  
Conflicts Of Interest ◽  
Expression Profiles ◽  
Acquired Resistance ◽  
Gene Array ◽  
Cell Counting ◽  
Control Group ◽  
Protein Levels ◽  
Significant Difference

Abstract Background: Multiple myeloma (MM) is among the most common hematologic malignancies. Proteasome inhibitor bortezomib (Bor) is one of the most effective drugs for treatment of MM. However, during long-term Bor treatment, MM cells may eventually develop acquired-resistance to Bor which results in recurrence and a poor prognosis of MM. Several researches show that E3 ubiquitin ligases (E3s) primarily determine the substrate specificity of ubiquitin proteasome system and play an essential role in Bor resistance of MM. NEDD4-1 E3s, a founding member of the Neural precursor cell-Expressed Developmentally Downregulated gene 4 (NEDD4) family, was proved to involve in the proliferation, migration, invasion of cancer cells and the sensitivity of anticancer therapies. Our current study aims to explore the role and underlying mechanism of NEDD4-1 in acquired resistance of Bor in MM. Methods: The mRNA and protein levels of NEDD4-1 and its substrates in MM cell lines (H929, LP-1, RPMI8226, OPM-2 and ARP-1) and MM patients were detected by Quantitative Realtime PCR and Western Blotting. Lentiviral plasmids containing shRNA against NEDD4-1 were transfected into MM cells. Cell viability, proliferation and apoptosis of MM cells were measured by Cell Counting kit8 (CCK8) and flow cytometry. Gene array was used to compare the gene expression profiles of a panel of Bor treated MM cells vs vehicle-treated MM cells. Results: Gene array showed NEDD4-1 was significantly increased in MM cells treated with Bor. MM cells (CD138+ plasma cells of the bone marrow) from refractory/recurrence patients expressed lower NEDD4-1 than primary patient myeloma cells. Also, MM cell lines H929, ARP-1, LP-1 highly expressed NEDD4-1 at mRNA and protein levels. RPMI8226 and OPM-2 were relatively low expressed. Cell growth assay displayed no significant difference in proliferation between the NEDD4-1 knockdown (KD) and the control group (P>0.05). After suppression of NEDD4-1 using shRNAs, the killing effect of Bor in MM was significantly weaker than the control group (P<0.05). We also found that PTEN was decreased in the NEDD4-1 KD H929 cell line. Otherwise, phospho-STAT3 (ser727) and oncoprotein c-Myc and Bcl-2 were upregulated. Conclusion: Collectively, our study reveals that inhibition of NEDD4-1 can reduce MM sensitivity to Bor via regulating PTEN, c-Myc and Bcl-2, may be related to JAK/STAT signaling pathway, which suggests that NEDD4-1 probably acts as a novel drug target and therapeutic paradigm in the battle against multiple myeloma. Disclosures No relevant conflicts of interest to declare.

ETV1 Is a Survival Gene That Is Expressed in a Subset of Multiple Myeloma

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2884-2884
Author(s):  
Seung-Jin Kim ◽  
Carlos S Moreno ◽  
Sagar Lonial ◽  
Lawrence H. Boise
Keyword(s):  
Multiple Myeloma ◽  
Vector Control ◽  
Cell Lines ◽  
Conflicts Of Interest ◽  
Expression Profiles ◽  
Mrna Level ◽  
Myeloma Cell ◽  
Over Expression ◽  
Ets Family

Abstract Abstract 2884 While several genes have been shown to participate in primary Ig translocations in about 50% of cases of multiple myeloma, it is still remains unclear how activation of these genes ultimately leads to a transformed phenotype. In nearly 15% of myeloma cases, t(4;14) results in the over-expression of MMSET and FGFR3. However the FGFR3 translocation is lost in about 25% of these patients. To identify genes associated with these changes we initially compared the gene expression profiles (GEP) of t(4;14) patients that expressed FGFR3 with those that did not. Using both supervised and unsupervised hierarchal clustering we were unable to identify significant differences associated with FGFR3 expression. Therefore we pooled these samples and compared them to GEP from normal plasma cells and MGUS patients to identify genes that were up-regulated in t(4;14) myelomas. As validation of this approach the two highest up-regulated genes were FGFR3 and MMSET (WHSC). Interestingly an additional gene that was significantly up-regulated (33 fold) was the ETS family transcription factor Ets variant gene 1 (ETV1; also called ER81). Further analysis of GEP data of MM patient samples revealed that ETV1 is primarily expressed in the genomically defined CD1, CD2 and MS subgroups in newly diagnosed patients (Arkansas dataset GSE4204). These data were confirmed in relapsed/refractory patients where expression was greatest in the 11q13 and 4p16 subsets (Tc classification, Mulligan dataset GSE9782). ETV1 is a member of the ETS family transcription factors and has been shown to be involved in recurrent translocations in prostate cancer and is also up-regulated in GIST. However no data exists on the role of ETV1 in MM. We investigated the expression of ETV1 in human myeloma cell lines (HMCL) and determined the effect of silencing on cell viability, proliferation, and drug responses. To determine whether ETV1 is expressed in MM cell lines, 10 HMCL were subjected to real-time PCR and western blot analysis. All ten cell lines expressed ETV1 with MM.1s expressing the lowest levels. Consistent with the GEP data from the patient samples, the t(4;14) and t(11;13) lines expressed 5.5–13-fold higher levels of ETV1 than MM.1s. Surprisingly the highest expresser was not from one of these translocation groups, as RPMI8226 displayed a 74-fold increase compared with MM.1s. Determination of the potential reason for this level of over-expression is currently underway. Protein levels of ETV1 also correlated with mRNA level for all MM cell lines. To functionally characterize the role of ETV1 in myeloma, we utilized shRNA-mediated knockdown in the KMS11 line. ETV1 knockdown had no effect on cell proliferation, but did result in increased apoptosis compared to the vector control KMS11 cells, suggesting a biological role for ETV1 in myeloma cell survival. Consistent with this possibility, we observed increased sensitivity to the Bcl-2 inhibitor ABT-737 and the HDAC inhibitors SAHA and Romidepsin in ETV1-shRNA bearing KMS11 when compared to vector control. These results provide the first line of evidence that ETV1 plays a significant role in a subset of MM and suggest that therapies targeting this gene could have an impact in a subset of MM patients. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Super-Enhancer Profiling Identifies Novel Oncogenes and Therapeutic Targets in Multiple Myeloma

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 362-362
Author(s):  
Jianbiao Zhou ◽  
Yunlu Jia ◽  
Tze King Tan ◽  
Tae-Hoon Chung ◽  
Takaomi Sanda ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Lines ◽  
Plasma Cell ◽  
Conflicts Of Interest ◽  
Cell Cancer ◽  
Ectopic Expression ◽  
Therapeutic Targets ◽  
Physical Interaction ◽  
Rna Seq ◽  
Normal Plasma

Background: Multiple myeloma (MM) is an aggressive neoplastic plasma cell cancer characterized by diversely cytogenetic abnormalities. MM can be divided into subtypes with immunoglobulin heavy chain (IGH) gene translocations involving CCND1-3, FGFR3/MMSET, MAFs and hyperdiploid myeloma containing trisomies of several odd numbered chromosomes 3, 5, 7, 9, 11, 15, 19, and 21. Although several new drugs have been introduced into clinic, treatment for MM patients remains challenge and refractory/resistant to therapy is often seen. Thus, a better understanding of the molecular pathogenesis of MM can lead to generate new prognostic classification and identify new therapeutic targets. Super-enhancers (SEs) are defined as large clusters of cis-acting enhancers, marked by high level bindings of acetylation of histone H3 lysine 27 (H3K27ac) and mediator complex. SEs have been shown to control genes for maintaining cellular identity and also key tumor drivers in various malignancies. Methods: H3K27Ac ChIP-seq and RNA-seq were performed on primary MM patient samples, MM cell lines. Normal plasma cells and lymphoma cell lines were served as controls. We systematically compared SEs and their associated genes of normal and cancerous tissue. THZ1, a CDK7 inhibitor, was used to efficiently down-regulate SE-associated genes. Combinatory analysis of THZ1-sensitive and SE-associated gene revealed a number of promising MM oncogenes. CRISPR/Cas9 technology and ectopic expression experiments in conjunction with cellular functional assays were performed to determine the effects of candidate SE-genes on MM cells. Circularized chromatin conformation capture followed by sequencing (4C-seq) was applied to explore the direct contact of SE and promoter. Results: SE analysis uncovered some cell lineage-specific transcription factors (TFs) and known oncogenes in MM. Several key TFs, including IRF4, PRDM1, MYC and XBP1, were identified in most MM samples, confirming the origin of MM cells. These data reinforce the concept that SE establishment is a key component of MM biology. The acquisition of SEs around oncogene drivers is widely observed during tumorigenesis. ST3GAL6 and ADM were two known oncogenic drivers in myeloma cells, which were associated with super-enhancers in all MM samples but not in normal plasma cell and lymphoma cells. We also found SE constituents for multiple subtype-specific key oncogenes such as CCND1 in t(11;14) cells, C-MAF in t(14;16) cells, and NSD2 and FGFR3 in t(4;14) cells. Furthermore, THZ1 showed prominent anti-neoplastic effect against MM cells. SE-associated genes were more sensitive to THZ1 compared with those genes associated with typical enhancers (TEs). By overlapping THZ1-sensitve gene with SE-associated genes, we identified a number of novel MM oncogenes, including MAGI2, EDEM3, HJURP, LAMP5, MBD1 and UCK2 as a potential druggable kinase. The expression level of MAGI2 and HJURP confers poor prognosis in several MM datasets. MAGI2 silencing in MM cells decreased cell proliferation and induced apoptosis. qRT-PCR and Western blot analysis confirmed the overexpression of HJURP in t(4;14) cells relative to non-t(4;14) MM cells. Furthermore, 4C-seq analysis revealed the physical interaction between HJURP-SE and promoter and THZ1 treatment diminished this interaction. Motif search at SE constituents revealed a highly significant enrichment of NSD2 recognition. Significant reduction of NSD2 binding at HJURP-SE region was observed in KMS11 infected with NSD2-specific shRNAs. Interestingly, blocking SE sites by CRISPR/Cas9i or silencing HJURP by shRNA led to decreased HJURP expression and cell apoptosis, whereas overexpression of this gene promoted cell growth. Taken together, our data demonstrated that HJURP is a novel SE-associated oncogene in t(4;14) MM. Conclusions: Our integrative approaches by combing H3K27Ac ChIP-seq, RNA-seq and THZ1-sensitive transcript defined the landscape of SE and identified SE-associated novel oncogenes, as well as lineage-specific TFs in MM. Furthermore, we also revealed subtype-specific SE-driving oncogenic program in MM. Taken together, these results not provide novel insight into the MM pathology, but also offer novel, potential therapeutic targets, such as MAGI2, and HJURP for the treatment of MM patients. Disclosures No relevant conflicts of interest to declare.

scholarly journals PDZ Binding Kinase (PBK) - a Novel Gene Driving Genomic Evolution in Multiple Myeloma

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 4474-4474
Author(s):  
Subodh Kumar ◽  
Leutz Buon ◽  
Srikanth Talluri ◽  
Jialan Shi ◽  
Hervé Avet-Loiseau ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Genomic Instability ◽  
Cell Lines ◽  
Excision Repair ◽  
Critical Role ◽  
Micronucleus Assay ◽  
Genomic Evolution ◽  
Dna Breaks ◽  
Functional Changes ◽  
Elevated Expression

Abstract As in all cancers, genomic instability leads to ongoing acquisition of new genetic changes in multiple myeloma (MM). This adaptability underlies the development of drug resistance and progression in MM. This genomic instability is driven by cellular processes, mainly related with DNA repair and perturbed by functional changes in limited number of genes. Since kinases play a critical role in the regulation of biological processes, including DNA damage/repair signaling and are relatively easy to screen for inhibitors, we investigated for novel genes involved in the acquisition of new genomic changes in MM. Using a large genomic database which had both the gene expression and CGH array-based copy number information (gse26863, n=246), we first identified a total of 890 expressed kinases in MM and correlated their expression with genomic instability defined as a change in ≥3 and/or 5 consecutive amplification and/or deletion events. We identified 198 kinases whose elevated expression correlated with increased genomic instability (based on FDR ≤ 0.05). Amongst these kinases, using univariate Cox survival analysis, elevated expression of 15 kinases correlated with poor overall as well as event free survival (P ≤0.05) in two MM datasets (IFM70, n=170; gse24080; n=559). We further confirmed the correlation of these 15 genes in both EFS and OS in additional two MM datasets (MMRF CoMMpass Study, IFM-DFCI 2009) as well as in additional solid tumor datasets from TCGA from patients with lung and pancreatic adenocarcinoma (P values ranging from 0.01 to <0.000002). A pathway analysis identified phosphorylation and regulation of proteasome pathway, mitotic spindle assembly/checkpoint, chromosomal segregation and cell cycle checkpoints as among major pathways regulated by these genes. To investigate the relevance of these genes with genomic instability, we performed a functional siRNA screen to evaluate impact of their suppression on homologous recombination (HR). PDZ Binding Kinase (PBK) was one of the top genes whose knockdown caused the maximal inhibition of HR activity in initial screen. To investigate it further in detail, we suppressed PBK in MM cells using shRNA and confirmed that its suppression significantly reduces HR activity. PBK-knockdown also reduced gH2AX levels (marker of DNA breaks) measured by Western blotting and decreased number of micronuclei (a marker of ongoing genomic rearrangements and instability) as assessed by flow cytometry . A small molecule inhibitor of PBK also confirmed a similar reduction in gH2AX levels as well as micronuclei, indicating inhibition of spontaneous DNA breaks and genomic instability. Using mass spectrometry and co-immunoprecipitation, we identified that PBK interacts with FEN1, a nuclease with roles in base excision repair and HR pathways. We confirmed that PBK induces phosphorylation of FEN1 and that inhibition of PBK, suppressed the phosphorylation of FEN1, RAD51 expression and gH2AX levels and it reversed FEN1-induced HR activity. These results confirm that phosphorylation of FEN1 nuclease by PBK contributes to its ability to impact DNA breaks, HR and genome stability in MM. PBK inhibition also significantly sensitized MM cells to melphalan and inhibited cell viability in a panel of MM cell lines (IC50 in MM cell lines ~20-30 nM vs ~100 nM in normal PBMCs) at the same time also reversed melphalan-induced genomic instability, as assessed by micronucleus assay. These data identify PBK as an important target affecting genomic instability, and its inhibitor as a potential drug, to inhibit genomic evolution and MM cell growth. Disclosures Munshi: OncoPep: Other: Board of director.

Dysregulated Apurinic/Apyrimidinic Endonucleases (Ape1 and Ape2) Lead to Genetic Instability in Multiple Myeloma.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1418-1418
Author(s):  
Masood A. Shammas ◽  
Hemant Koley ◽  
Sima Shah ◽  
Ramesh B. Batchu ◽  
Pierfrancesco Tassone ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Homologous Recombination ◽  
Genomic Instability ◽  
Cell Lines ◽  
Plasma Cells ◽  
Dna Recombination ◽  
Endonuclease Activity ◽  
Single Nucleotide ◽  
Genetic Changes

Abstract Multiple myeloma (MM) is associated with significant genomic instability. Homologous recombination (HR), which is elevated in MM, is considered to be responsible for this instability. As endonucleases play an important role in mediating HR, here we have evaluated the role of endonuclease in biology and progression of MM. Gene expression profile using Affymetrix U133 array showed &gt; 2 fold elevation of Ape1 or Ape2 or both in 5 of 6 MM cell lines and 12 of 15 patient samples. Immunocytochemistry confirmed upregulation of Ape1 protein in MM cell lines. A Plasmid degradation assay confirmed significantly elevated endonuclease activity in MM cells compared to normal plasma cells. To identify the pre-dominating endonuclease activity, the degradation assay was carried out in the presence of specific endonuclease inhibitors. Harmane and methoxyamine (MA), specific inhibitors of apurinic/apyrimidinic endonucleases effectively inhibited significant endonuclease activity, while other endonuclease inhibitors ACPD and FK506 had minimal effects, confirming predominant role of apurinic/apyrimidinic endonucleases (APE) in mediating increased endonuclease activity in MM. We investigated the role of elevated APE endonuclease activity on DNA recombination and subsequent genomic re-arrangements. Using a plasmid-based assay we have previously demonstrated significantly elevated homologous recombination (HR) in MM. Inhibition of endonuclease by methoxyamine suppressed HR activity by 85 ± 2% in MM cells. Next, we evaluated whether inhibition of HR by methoxyamine can affect the frequency of acquisition of new genetic changes in MM cells using single nucleotide polymorphism (SNP) arrays (Affymetrix) as indicator of genomic instability. In three independent experiments, methoxyamine reduced the acquisition of new loss of heterozygocity (LOH) loci by an average of 71%. These data suggest that the dysregulated APE endonucleases contribute significantly to the genomic instability, acquisition of new mutations and progression of MM and provides the rationale for targeting endonuclease activity to prevent disease progression including development of drug resistance.

Molecular Basis of Genomic Instability and Progression in Multiple Myeloma: Potential Role of Apurinic (Apyrimidinic) Endonuclease.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1561-1561
Author(s):  
Masood A. Shammas ◽  
Hemanta Koley ◽  
Paola Neri ◽  
Pierfrancesco Tassone ◽  
Ramesh B. Batchu ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Genomic Instability ◽  
Cell Lines ◽  
Molecular Basis ◽  
Endonuclease Activity ◽  
Ap Endonuclease ◽  
Myeloma Cells ◽  
Genome Wide ◽  
New Mutations

Abstract Genetic instability is a prominent feature of most cancers including multiple myeloma (MM) and is responsible for ongoing accrual of mutational changes which may lead to development of drug resistance and metastasis. The molecular basis for the generation of genetic diversity in MM is therefore extremely important to understand carcinogenesis and to identify novel targets for treatment. As genomic rearrangements require excision of DNA, we hypothesized that an elevated endonuclease activity may induce recombination and subsequent genomic instability in cancer cells. We developed a plasmid degradation assay that confirmed significantly elevated endonuclease activity in MM cells compared to normal plasma cells. To identify the pre-dominating endonuclease the degradation assay was carried out in the presence of specific endonuclease inhibitors, which identified apurinic/apyrimidinic endonuclease (Ape1 and Ape2) as the predominant endonucleases in mediating increased endonuclease activity in MM. Gene expression analysis confirmed &gt; 2 fold elevation of Ape1 or Ape2 or both in 5 of 6 MM cell lines and 12 of 15 patient samples. Both immunocytochemistry and western blot analyses confirmed upregulation of Ape1 protein in all MM cell lines and patient samples. Next, we investigated the role of elevated APE endonuclease activity in DNA recombination and subsequent genomic re-arrangements. Using a plasmid-based assay we have previously demonstrated significantly elevated homologous recombination (HR) in MM. To investigate the role of elevated AP endonuclease activity in MM, we cultured myeloma cells in the presence of methoxyamine (MX), which specifically inhibits AP endonuclease activity, and evaluated its effect on HR activity and genome-wide appearance of new mutations. Exposure of intact myeloma cells to MX resulted in &gt; 90% inhibition of HR activity and a significant (71±10.9%; p&lt;0.05) reduction in the appearance of new mutations compared to untreated cells, as assessed by genome-wide loss of heterozygosity (LOH) assay (Affymetrix). We also evaluated the effects of overexpression of Ape1 & 2 in normal fibroblasts which have low endonuclease activity. The transgenic upregulation of AP endonucleases (Ape1 and Ape2) in normal cells led to a significant increase in the lecombination activity, leading to a marked mutational instability as indicated by the appearance of over 20,063 and 20,143 new LOH loci per 100,000 polymorphic regions examined throughout the genome, at population doublings 25 and 50 respectively. Mutational instability was also associated with chromosomal instability confirmed by spectral karyotyping of these cells showing significant numerical and structural chromosomal abnormalities. These changes were associated with indefinite growth of cells and formation of tumors when injected in SCID mice. These data suggest that elevated AP endonuclease may be responsible for mutational and chromosomal instabilities, leading to progression of myeloma.

Bortezomib Inhibits mTOR Pathway in Multiple Myeloma Cell Lines Via Induced Expression of REDD1.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 242-242
Author(s):  
Olivier Decaux ◽  
Monique Clement ◽  
Florence Magrangeas ◽  
Laurence Lode ◽  
Catherine Charbonnel ◽  
...  
Keyword(s):  
Gene Expression ◽  
Multiple Myeloma ◽  
Cell Size ◽  
Cell Lines ◽  
Stress Responses ◽  
Cellular Proliferation ◽  
Expression Profiles ◽  
Mtor Pathway ◽  
Molecular Signature ◽  
Gene And Protein Expression

Abstract Pharmacogenomic profiles of genes involved in bortezomib - dexamethasone response may help to understand resistance and could provide new therapeutic targets as well as contributing to novel prognostic markers in multiple myeloma. We have used gene expression profiling to analyze the complex signaling pathways regulating the response to bortezomib - dexamethasone. Gene expression profiles were established in 9 cell lines, derived from 9 myeloma patients, incubated or not with a combination of bortezomib 10 nM and dexamethasone 1 μM. These concentrations correspond to the ones used for patients in the IFM 2005-01. Cells were collected after 6 hours of treatment. We focused our interest in early response genes, making the hypothesis that the comprehension of early effects would help to better understand the mechanisms of resistance that take place in at least two third of myeloma patients. Supervised analysis with permutations identified significantly up regulated genes involved in stress responses (heat shocks proteins, RTP801/dig2/REDD1/DDIT4), endoplasmic reticulum stress (HERP/HERPUD1, gadd145/CHOP/DDIT3), ubiquitin/proteasome pathway (proteasome 26S subunits PSMB7, PSMC4, PSMD3 and PSMD13), unfolded protein response (such as SQSTM1, ATF4) or redox equilibrium (PLRX, PRDX1). We assumed that these genes might represent a molecular signature of response to bortezomib and provide important insight into the complex mechanisms of action of these drugs. We focused on REDD1 a gene cloned in 2002 that is known to be rapidly induced by a wide variety of stress conditions (arsenic, hypoxia, dexamethasone, thapsigargin, tunimycin and heat shock) and DNA damages (ionizing radiation, ultraviolet radiation, DNA alkylant). We found that both REDD1 gene and protein expression were early and highly induced after bortezomib exposure alone or in combinaison with dexamethasone. This effect was dependent upon cell line: REDD1 was overexpressed within two hours in resistant cell lines in association with a cell size decrease while in sensitive cell lines, neither REDD1 induction nor morphological changes occured. REDD1 induction was associated with the dephosphorylation of S6K1, a key substrat of mTOR, a protein kinase which controls cell growth and cell size in response to various signals. SiRNA studies confirmed that bortezomib lead to a negative regulation of mRTor activity mediated by REDD1: disruption of REDD1 abrogates both S6K1 phosphorylation and early transitory cell size reduction. Our results are in accordance with data obtained in mouse showing an early regulation of mTOR pathway and cellular proliferation induced by REDD1 expression in response to stress. Our study suggests that mTOR regulation could be a resistance mechanism mediated by REDD1 expression. As we found that REDD1 was differentially induced in primary plasma cells from patients, this gene expression could help to predict response to bortezomib. Our objective is now to clarify the pathway that links bortezomib to REDD1 in multiple myeloma and to investigate REDD1 expression in patients enrolled in IFM 2005-01 clinical trial.

Cooperation of MLL/AF10(OM-LZ) with K-Ras Mutation Induced Myeloid Sarcoma in a Mouse Bone Marrow Transplantation Model.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1964-1964
Author(s):  
Jen-Fen Fu ◽  
Lee-Yung Shih
Keyword(s):  
Bone Marrow ◽  
Cell Lines ◽  
Bone Marrow Cells ◽  
Conflicts Of Interest ◽  
Fusion Gene ◽  
Flow Cytometric Analysis ◽  
Myeloid Sarcoma ◽  
Mouse Bone Marrow ◽  
Myeloproliferative Disease ◽  
Multiple Tumor

Abstract Abstract 1964 Poster Board I-987 We analyzed genetic mutations in a large cohort of AML patients and found that two of the five patients with MLL/AF10 and N-/K-RAS mutations had cutaneous tumors (myeloid sarcomas). To study the cooperative role of MLL/AF10 and N-/K-RAS in the formation of myeloid sarcoma, we established two cell lines by retroviral transduction of MLL/AF10(OM-LZ) and K-RASG12C into GFP-B6 mouse bone marrow cells. Flow cytometric analysis revealed that the cells with MLL/AF10(OM-LZ) and K-RASG12C showed a decreased Mac-1 and CD115 expression when compared with the cells with a single MLL/AF10(OM-LZ) mutation. Microarray and RT-PCR analyses revealed an increased gene expression in Hoxa10 and Meis1, but not Hoxa9. In addition, the phagocytosis related genes, Cybb and Lyz were decreased in the cells harboring MLL/AF10(OM-LZ) and K-RASG12C. These results suggested that cooperation of MLL/AF10(OM-LZ) and K-RASG12C mutations blocked the cells in a more primitive hematopoietic stage. When the two cell lines were intra-peritoneally injected into B6 mice, the mice developed myeloproliferative disease-like myeloid leukemia as that of the mice transplanted with cells carrying a single MLL/AF10(OM-LZ) fusion gene. The median survival time were 33±4.2 and 31.6±5.1 days, respectively, which were shorter than that of the mice transplanted with cells carrying a single MLL/AF10(OM-LZ) fusion gene (49.8±5.0 days). We found that the majority (84%) of mice transplanted with cells harboring both MLL/AF10(OM-LZ) and K-RASG12C mutations formed multiple tumor masses involving gastrointestinal tract, kidney, peritoneum, paraspinal soft tissue, and/or skin. Cytological examination from the imprint smears of tumor masses showed massive infiltrates of leukemia blastic cells. Immunohistochemical stains of the paraffin-fixed histological sections of tumor masses were positive for GFP, confirmed that the tumor cells were generated from the transplanted cell lines. We have established a mouse model which can be used for further study of the myeloid sarcoma formation. Disclosures: No relevant conflicts of interest to declare.

HOXA9 Is a Novel Therapeutic Target in Multiple Myeloma.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 832-832 ◽  
Author(s):  
Michael A Chapman ◽  
Jean-Philippe Brunet ◽  
Jonathan J Keats ◽  
Angela Baker ◽  
Mazhar Adli ◽  
...  
Keyword(s):  
Gene Expression ◽  
Multiple Myeloma ◽  
Histone Modification ◽  
Cell Lines ◽  
Therapeutic Target ◽  
Copy Number ◽  
Conflicts Of Interest ◽  
Specific Expression ◽  
Aberrant Expression ◽  
High Level

Abstract Abstract 832 We hypothesized that new therapeutic targets for multiple myeloma (MM) could be discovered through the integrative computational analysis of genomic data. Accordingly, we generated gene expression profiling and copy number data on 250 clinically-annotated MM patient samples. Utilizing an outlier statistical approach, we identified HOXA9 as the top candidate gene for further investigation. HOXA9 expression was particularly high in patients lacking canonical MM chromosomal translocations, and allele-specific expression analysis suggested that this overexpression was mono-allelic. Indeed, focal copy number amplifications at the HOXA locus were observed in some patients. Outlier HOXA9 expression was further validated in both a collection of 52 MM cell lines and 414 primary patient samples previously described. To further verify the aberrant expression of HOXA9 in MM, we performed quantitative RT-PCR, which confirmed expression in all MM patients and cell lines tested, with high-level expression in a subset. To further investigate the mechanism of aberrant HOXA9 expression, we interrogated the pattern of histone modification at the HOXA locus because HOXA gene expression is particularly regulated by such chromatin marks. Accordingly, immunoprecipitation studies showed an aberrantly low level of histone 3 lysine 27 trimethylation marks (H3K27me3) at the HOXA9 locus. H3K27me3 modification is normally associated with silencing of HOXA9 in normal B-cell development. As such, it appears likely that the aberrant expression of HOXA9 in MM is due at least in part to defects in histone modification at this locus. To determine the functional consequences of HOXA9 expression in MM, we performed RNAi-mediated knock-down experiments in MM cell lines. Seven independent HOXA9 shRNAs that diminished HOXA9 expression resulted in growth inhibition of 12/14 MM cell lines tested. Taken together, these experiments indicate that HOXA9 is essential for survival of MM cells, and that the mechanism of HOXA9 expression relates to aberrant histone modification at the HOXA9 locus. The data thus suggest that HOXA9 is an attractive new therapeutic target for MM. Disclosures: No relevant conflicts of interest to declare.

Transcriptional Silencing of the Wnt-Antagonist Dickkopf-1 (DKK1) by Promoter Methylation Unleashes Aberrant Wnt Signaling In Advanced Multiple Myeloma

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1919-1919
Author(s):  
Kinga A Kocemba ◽  
Richard W Groen ◽  
Harmen van Andel ◽  
Karene Mahtouk ◽  
Marie Jose Kersten ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Wnt Signaling ◽  
Cell Lines ◽  
Wnt Pathway ◽  
Conflicts Of Interest ◽  
Cpg Island ◽  
Nuclear Accumulation ◽  
Aberrant Methylation ◽  
Dkk1 Expression ◽  
Osteolytic Bone Disease

Abstract Abstract 1919 Aberrant activation of the Wnt/β-catenin pathway is implicated in driving the formation of various human cancers. Recent studies indicate that the Wnt pathway plays at least two distinct roles in the pathogenesis of multiple myeloma (MM): i) Aberrant, presumably autocrine, activation of canonical Wnt signaling in MM cells promotes tumor proliferation and metastasis; ii) Overexpression of the Wnt inhibitor Dickkopf1 (DKK1), contributes to osteolytic bone disease by inhibiting osteoblast differentiation. Since DKK1 itself is a target of TCF/β-catenin mediated transcription, these findings suggests the presence of a negative feedback loop in MM, in which DKK1 acts as a potential tumor suppressor. In line with this hypothesis, we show here that DKK1 expression is lost in most MM cell lines and in a subset of patients with advanced MM. This loss is correlated with activation of the Wnt pathway, as demonstrated by increased nuclear accumulation of β-catenin. Analysis of the DKK1 promoter revealed CpG island methylation in several MM cell lines as well as in MM cells from patients with advanced MM. Moreover, demethylation of the DKK1 promoter restores DKK1 expression, which results in inhibition of β-catenin/TCF-mediated gene transcription in MM lines. Taken together, our data identify aberrant methylation of the DKK1 promoter as a cause of DKK1 silencing in advanced stage MM, which may play an important role in the progression of MM by unleashing Wnt signaling. Disclosures: No relevant conflicts of interest to declare.

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