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While multi-drug combinations and continuous treatment have become standard for multiple myeloma, the disease remains incurable. Repurposing drugs that are currently used for other indications could provide a novel approach to improve the therapeutic efficacy of standard multiple myeloma treatments. Here, we assessed the anti-tumor effects of cardiac drugs called β-blockers as a single agent and in combination with commonly used anti-myeloma therapies. Expression of the β 2 -adrenergic receptor correlated with poor survival outcomes in patients with multiple myeloma. Targeting the β 2 -adrenergic receptor (β 2 AR) using either selective or non-selective β-blockers reduced multiple myeloma cell viability, and induced apoptosis and autophagy. Blockade of the β 2 AR modulated cancer cell metabolism by reducing the mitochondrial respiration as well as the glycolytic activity. These effects were not observed by blockade of β 1 -adrenergic receptors. Combining β 2 AR blockade with the chemotherapy drug melphalan or the proteasome inhibitor bortezomib significantly increased apoptosis in multiple myeloma cells. These data identify the therapeutic potential of β 2 AR-blockers as a complementary or additive approach in multiple myeloma treatment and support the future clinical evaluation of non-selective β-blockers in a randomized controlled trial. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland., (© 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.)

Background: Human multiple myeloma (MM) cell lines (HMCLs) have been widely used to understand the molecular processes that drive MM biology. Epigenetic modifications are involved in MM development, progression, and drug resistance. A comprehensive characterization of the epigenetic landscape of MM would advance our understanding of MM pathophysiology and may attempt to identify new therapeutic targets. Methods: We performed chromatin immunoprecipitation sequencing to analyze histone mark changes (H3K4me1, H3K4me3, H3K9me3, H3K27ac, H3K27me3 and H3K36me3) on 16 HMCLs. Results: Differential analysis of histone modification profiles highlighted links between histone modifications and cytogenetic abnormalities or recurrent mutations. Using histone modifications associated to enhancer regions, we identified super-enhancers (SE) associated with genes involved in MM biology. We also identified promoters of genes enriched in H3K9me3 and H3K27me3 repressive marks associated to potential tumor suppressor functions. The prognostic value of genes associated with repressive domains and SE was used to build two distinct scores identifying high-risk MM patients in two independent cohorts (CoMMpass cohort; n = 674 and Montpellier cohort; n = 69). Finally, we explored H3K4me3 marks comparing drug-resistant and -sensitive HMCLs to identify regions involved in drug resistance. From these data, we developed epigenetic biomarkers based on the H3K4me3 modification predicting MM cell response to lenalidomide and histone deacetylase inhibitors (HDACi). Conclusions: The epigenetic landscape of MM cells represents a unique resource for future biological studies. Furthermore, risk-scores based on SE and repressive regions together with epigenetic biomarkers of drug response could represent new tools for precision medicine in MM., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Multiple myeloma (MM) is an (epi)genetic highly heterogeneous plasma cell malignancy that remains mostly incurable. Deregulated expression and/or genetic defects in epigenetic-modifying enzymes contribute to high-risk disease and MM progression. Overexpression of the histone methyltransferase G9a was reported in several cancers, including MM, correlating with disease progression, metastasis, and poor prognosis. However, the exact role of G9a and its interaction partner G9a-like protein (GLP) in MM biology and the underlying mechanisms of action remain poorly understood. Here, we report that high G9a RNA levels are associated with a worse disease outcome in newly diagnosed and relapsed MM patients. G9a/GLP targeting using the specific G9a/GLP inhibitors BIX01294 and UNC0638 induces a G1-phase arrest and apoptosis in MM cell lines and reduces primary MM cell viability. Mechanistic studies revealed that G9a/GLP targeting promotes autophagy-associated apoptosis by inactivating the mTOR/4EBP1 pathway and reducing c-MYC levels. Moreover, genes deregulated by G9a/GLP targeting are associated with repressive histone marks. G9a/GLP targeting sensitizes MM cells to the proteasome inhibitors (PIs) bortezomib and carfilzomib, by (further) reducing mTOR signaling and c-MYC levels and activating p-38 and SAPK/JNK signaling. Therapeutic treatment of 5TGM1 mice with BIX01294 delayed in vivo MM tumor growth, and cotreatment with bortezomib resulted in a further reduction in tumor burden and a significantly prolonged survival. In conclusion, we provide evidence that the histone methyltransferases G9a/GLP support MM cell growth and survival by blocking basal autophagy and sustaining high c-MYC levels. G9a/GLP targeting represents a promising strategy to improve PI-based treatment in patients with high G9a/GLP levels., (© 2021 by The American Society of Hematology.)

Background: Multiple myeloma (MM) is a malignant plasma cell disease with a poor survival, characterized by the accumulation of myeloma cells (MMCs) within the bone marrow. Epigenetic modifications in MM are associated not only with cancer development and progression, but also with drug resistance., Methods: We identified a significant upregulation of the polycomb repressive complex 2 (PRC2) core genes in MM cells in association with proliferation. We used EPZ-6438, a specific small molecule inhibitor of EZH2 methyltransferase activity, to evaluate its effects on MM cells phenotype and gene expression prolile., Results: PRC2 targeting results in growth inhibition due to cell cycle arrest and apoptosis together with polycomb, DNA methylation, TP53, and RB1 target genes induction. Resistance to EZH2 inhibitor is mediated by DNA methylation of PRC2 target genes. We also demonstrate a synergistic effect of EPZ-6438 and lenalidomide, a conventional drug used for MM treatment, activating B cell transcription factors and tumor suppressor gene expression in concert with MYC repression. We establish a gene expression-based EZ score allowing to identify poor prognosis patients that could benefit from EZH2 inhibitor treatment., Conclusions: These data suggest that PRC2 targeting in association with IMiDs could have a therapeutic interest in MM patients characterized by high EZ score values, reactivating B cell transcription factors, and tumor suppressor genes.

Enhancer of zeste homolog 2 (EZH2) is a histone methyltransferase that functions as the catalytic subunit of the polycomb repressive complex 2 (PRC2). PRC2 represses gene transcription through tri-methylation of lysine 27 of histone 3 (H3K27me3) by its catalytic subunit EZH2. EZH2 is also involved in normal B cell differentiation. EZH2 deregulation has been described in many cancer types including hematological malignancies. The oncogenic addiction of tumor cells to EZH2 represents a therapeutic target in several hematological malignancies and solid cancers. Specific small molecules have been recently developed to target cancer cells with EZH2 overexpression or activating mutation. Their therapeutic potential is currently under evaluation. In particular, EZH2 is overexpressed in multiple myeloma (MM), a neoplasia characterized by the accumulation of clonal plasma cells within the bone marrow, with biological functions in the pathophysiology. This review summarizes the roles of EZH2 in B cell differentiation and pathologic hematological processes with a particular focus in multiple myeloma. We also discuss recent advances in the development of EZH2 inhibitors for the personalized treatment of patients with hematological malignancies., (Copyright © 2018 Société Française du Cancer. Published by Elsevier Masson SAS. All rights reserved.)

Background: Multiple myeloma (MM) is the second most common hematologic malignancy. Aberrant epigenetic modifications have been reported in MM and could be promising therapeutic targets. As response rates are overall limited but deep responses occur, it is important to identify those patients who could indeed benefit from epigenetic-targeted therapy., Methods: Since HDACi and DNMTi combination have potential therapeutic value in MM, we aimed to build a GEP-based score that could be useful to design future epigenetic-targeted combination trials. In addition, we investigated the changes in GEP upon HDACi/DNMTi treatment., Results: We report a new gene expression-based score to predict MM cell sensitivity to the combination of DNMTi/HDACi. A high Combo score in MM patients identified a group with a worse overall survival but a higher sensitivity of their MM cells to DNMTi/HDACi therapy compared to a low Combo score. In addition, treatment with DNMTi/HDACi downregulated IRF4 and MYC expression and appeared to induce a mature BMPC plasma cell gene expression profile in myeloma cell lines., Conclusion: In conclusion, we developed a score for the prediction of primary MM cell sensitivity to DNMTi/HDACi and found that this combination could be beneficial in high-risk patients by targeting proliferation and inducing maturation.

Background: Multiple myeloma (MM) is an incurable clonal plasma cell malignancy. The constitutive expression of HIF-1α in MM suggests that inhibition of HIF-1α-mediated transcription represents an interesting target in MM., Methods: As p300 is a crucial co-activator of hypoxia-inducible transcription, disrupting the complex HIF-1α/p300 to target HIF activity appears to be an attractive strategy., Results: We reported that chetomin, an inhibitor of HIF-1α/p300 interaction, exhibits antitumour activity in human myeloma cell lines and primary MM cells from patients., Conclusions: Our data suggest that chetomin may be of clinical value in MM and especially for patients characterised by a high EP300/HIF-1α expression and a poor prognosis.

Krüppel-like factor 4 is a transcription factor with anti-proliferative effects in differentiated cells, but with the ability to reprogram adult cells into cell-cycling pluripotent cells. In cancer, Krüppel-like factor 4 acts as either an anti-oncogene or an oncogene. We analyzed Krüppel-like factor 4 gene expression in multiple myeloma using Affymetrix microarrays. We generated conditionally expressing Krüppel-like factor 4 myeloma cell lines to investigate the function of this gene in myeloma biology. Krüppel-like factor 4 gene expression is high in normal plasma cells, but reduced in primary multiple myeloma cells from two-thirds of patients. It is not expressed by any human myeloma cell line due to promoter methylation. Conditional expression of Krüppel-like factor 4 led to complete cell cycle blockade, mainly in G1 phase, with no major apoptosis. This blockade was associated with induction of p21(Cip1) and p27(Kip1) in cell lines with an intact p53 pathway, and of p27(Kip1) only in those with an impaired p53 pathway. Krüppel-like factor 4 is highly expressed in the poor prognostic MS group with t(4;14) translocation and in the good prognostic CD-1 group with t(11;14) or t(6;14). The apparent contradiction of cell cycle inhibitor Krüppel-like factor 4 expression in patients with poor prognosis could be reconciled since its expression increased the resistance of myeloma cell lines to melphalan. In conclusion, we describe for the first time that Krüppel-like factor 4 could play a critical role in controlling the cell cycle and resistance to alkylating agents in multiple myeloma cells.

Multiple myeloma is characterized by the clonal expansion of malignant plasma cells (multiple myeloma cells [MMCs]), in the bone marrow. Osteolytic bone lesions are detected in 80% of patients because of increased osteoclastic bone resorption and reduced osteoblastic bone formation. MMCs are found closely associated with sites of increased bone resorption. Osteoclasts strongly support MMC survival in vitro. To further elucidate the mechanisms involved in osteoclast/MMC interaction, we have identified 552 genes overexpressed in osteoclasts compared with other bone marrow cell subpopulations. Osteoclasts express specifically genes coding for 4 CCR2-targeting chemokines and genes coding for MMC growth factors. An anti-CCR2 monoclonal antibody blocked osteoclast chemoattractant activity for MMC, and CCR2 chemokines are also MMC growth factors, promoting mitogen-activated protein kinase activation in MMC. An anti-insulin growth factor-1 receptor monoclonal antibody completely blocked the osteoclast-induced survival of MMC suppressing both osteoclast and MMC survival. Specific a proliferation-inducing ligand or IL-6 inhibitors partially blocked osteoclast-induced MMC survival. These data may explain why newly diagnosed patients whose MMC express high levels of CCR2 present numerous bone lesions. This study displays additional mechanisms involved in osteoclast/MMC interaction and suggests using CCR2 and/or insulin growth factor-1 targeting strategies to block this interaction and prevent drug resistance.

Objective: Multiple myeloma is a plasma cell neoplasm characterized by the accumulation of malignant plasma cells within the bone marrow. This disease remains incurable despite major treatment improvements. However, gene expression profiling of multiple myeloma cells (MMC) may lead to identification of new therapeutic targets., Materials and Methods: Using Affymetrix microarrays, we identified the overexpression of the MYEOV gene in MMC of 171 patients with newly diagnosed multiple myeloma compared to normal plasma cells., Results: The MYEOV gene was present (Affymetrix call) in 79% of MMC and in 15% of normal plasma cells. MYEOV gene is not expressed in cells of the patients' bone marrow environment. The downregulation of MYEOV gene reduced the growth of a MYEOV(present) myeloma cell line, unlike a MYEOV(absent) one. Patients with MYEOV(absent) MMC have an increased event-free survival compared to patients with MYEOV(present) MMC, after high-dose therapy and stem cell transplantation and a trend for increased overall survival. In a Cox proportional hazard model, MYEOV expression in MMC is predictive for event-free survival for patients independently of International Staging System stage, t(4;14) translocation, albumin, or B2M serum levels. A knockout of MYEOV significantly reduced the growth of MMC., Conclusions: Thus, MYEOV expression is a prognostic factor for patients with multiple myeloma, in part through a role of MYEOV in the control of MMC proliferation., (Copyright © 2010 ISEH - Society for Hematology and Stem Cells. Published by Elsevier Inc. All rights reserved.)

Multiple myeloma (MM) is proposed to consist of two main pathogenetic groups. Although hyperdiploid MM (HD) is characterized by multiple trisomies of odd chromosomes, in nonhyperdiploid MM (NHD), one of the recurrent primary immunoglobulin heavy chain (IGH) translocations and deletion of chromosome 13 can frequently be found. In this study, we analyzed gene-expression profiles of patients with previously untreated MM. Fifty-four genes were significantly differentially expressed between the two groups. NPM1 was upregulated in HD. The differential expression of 25 genes, including NPM1 and 13 ribosomal protein genes, was validated using a published gene expression data set. The overexpression of NPM1 in HD was further confirmed by quantitative real-time PCR and Western blotting. NPM1 was significantly overexpressed in HD as the result of a gain of chromosome 5. Insertions into exon 12 of NPM1 were not detected. NPM1 was localized to the nucleoli of MM cells. Furthermore, HD was associated with an overexpression of ribosomal protein genes, independent of their localization on the trisomic or other chromosomes. Our results indicate that the gain of chromosome 5 might play an important role in the pathogenesis of HD.

Using Affymetrix microarrays, we identified the expression of the CD200 gene in multiple myeloma cells (MMCs) of 112 patients with newly diagnosed multiple myeloma (MM). The CD200 gene was either absent or present (Affymetrix call) in 22% and 78% of MMCs, respectively. The CD200 gene is not expressed in cells of the patients' bone marrow (BM). CD200 is a membrane glycoprotein that imparts an immunoregulatory signal through CD200R, leading to the suppression of T-cell-mediated immune responses. Patients with CD200(absent) MMCs have an increased event-free survival (EFS; 24 months) compared with patients with CD200(present) MMCs (14 months), after high-dose therapy and stem cell transplantation. In a Cox proportional-hazard model, the absence or presence of CD200 expression in MMCs is predictive for EFS for patients independently of ISS stage or beta2M serum levels. Thus, CD200 is an independent prognosis factor for patients with MM that could represent a new therapeutic target in MM.

While multi‐drug combinations and continuous treatment have become standard for multiple myeloma, the disease remains incurable. Repurposing drugs that are currently used for other indications could provide a novel approach to improve the therapeutic efficacy of standard multiple myeloma treatments. Here, we assessed the anti‐tumor effects of cardiac drugs called β‐blockers as a single agent and in combination with commonly used anti‐myeloma therapies. Expression of the β2‐adrenergic receptor correlated with poor survival outcomes in patients with multiple myeloma. Targeting the β2‐adrenergic receptor (β2AR) using either selective or non‐selective β‐blockers reduced multiple myeloma cell viability, and induced apoptosis and autophagy. Blockade of the β2AR modulated cancer cell metabolism by reducing the mitochondrial respiration as well as the glycolytic activity. These effects were not observed by blockade of β1‐adrenergic receptors. Combining β2AR blockade with the chemotherapy drug melphalan or the proteasome inhibitor bortezomib significantly increased apoptosis in multiple myeloma cells. These data identify the therapeutic potential of β2AR‐blockers as a complementary or additive approach in multiple myeloma treatment and support the future clinical evaluation of non‐selective β‐blockers in a randomized controlled trial. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland. [ABSTRACT FROM AUTHOR]

Multiple myeloma (MM) is a malignancy characterized by accumulation of malignant plasma cells within the bone marrow (BM). MM is considered mostly without definitive treatment because of the inability of standard of care therapies to overcome drug-resistant relapse. Genotoxic agents are used in the treatment of MM and exploit the fact that DNA double-strand breaks are highly cytotoxic for cancer cells. However, their mutagenic effects are well-established and described. According to these effects, chemotherapy could cause harmful DNA damage associated with new driver genomic abnormalities providing selective advantage, drug resistance, and higher relapse risk. Several mechanisms associated with MM cell (MMC) resistance to genotoxic agents have been described, underlining MM heterogeneity. The understanding of these mechanisms provides several therapeutic strategies to overcome drug resistance and limit mutagenic effects of treatment in MM. According to this heterogeneity, adopting precision medicine into clinical practice, with the development of biomarkers, has the potential to improve MM disease management and treatment. [ABSTRACT FROM AUTHOR]

The anaphase promoting complex/cyclosome (APC/C) is an ubiquitin ligase involved in cell cycle. During the metaphase-anaphase transition the APC/C is activated by Cdc20. The aim of this study is to elucidate the importance and therapeutic potential of APC/C and its co-activator Cdc20 in multiple myeloma (MM). Gene expression analysis revealed that Cdc20 was expressed at higher levels in gene expression-based high-risk MM patients. Moreover, high Cdc20 expression correlated with poor prognosis. Treatment of human myeloma cell lines with proTAME, an APC/C inhibitor, resulted in an accumulation of APC/CCdc20 substrate cyclin B1 and an accumulation of cells in metaphase. Moreover we observed a significant dose-dependent decrease in viability and increase in apoptosis in MM cells upon proTAME treatment. The induction of apoptosis was accompanied with caspase 3, 8, 9 and PARP cleavage. A similar metaphase arrest and induction of apoptosis were obtained with specific knockdown of Cdc20. In addition, we demonstrated the accumulation of Bim was partially responsible for the observed cell death. Combining proTAME with another APC/C inhibitor apcin or the alkylating agent melphalan resulted in enhanced anti-MM activity. This study suggests that the APC/C and its co-activator Cdc20 could be a new and promising target especially in high-risk MM patients.

Abstract: The six-transmembrane epithelial antigen of prostate (STEAP) protein was identified in advanced prostate cancer and is up-regulated in multiple cancer cell lines, including prostate, bladder, colon, ovarian, and Ewing sarcoma. STEAP1 was described as a suitable antigen for T-cell-based or antibody-based immunotherapy. We have investigated the expression of STEAP1 in 40 human tumor types – brain, epithelial, lymphoid – and in their normal tissue counterparts using publicly available gene expression data, including the Oncomine Cancer Microarray database. STEAP1 was found significantly overexpressed in 11 cancers. In addition, high STEAP1 expression was associated with poor overall survival in colorectal cancer, diffuse large B cell lymphoma, acute myeloid leukemia and multiple myeloma. Taken together, these data suggest that STEAP1 is a potential therapeutic target for T-cell based immunotherapy or antibody therapy in a large panel of cancers. [Copyright &y& Elsevier]

Plasma cells (PC) are the main effectors of adaptive immunity, responsible for producing antibodies to defend the body against pathogens. They are the result of a complex highly regulated cell differentiation process, taking place in several anatomical locations and involving unique genetic events. Pathologically, PC can undergo tumorigenesis and cause a group of diseases known as plasma cell dyscrasias, including multiple myeloma (MM). MM is a severe disease with poor prognosis that is characterized by the accumulation of malignant PC within the bone marrow, as well as high clinical and molecular heterogeneity. MM patients frequently develop resistance to treatment, leading to relapse. Polycomb group (PcG) proteins are epigenetic regulators involved in cell fate and carcinogenesis. The emerging roles of PcG in PC differentiation and myelomagenesis position them as potential therapeutic targets in MM. Here, we focus on the roles of PcG proteins in normal and malignant plasma cells, as well as their therapeutic implications. [ABSTRACT FROM AUTHOR]