Browsing by Author "Galson, Deborah L."

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    EZH2 or HDAC1 Inhibition Reverses Multiple Myeloma-Induced Epigenetic Suppression of Osteoblast Differentiation
    (American Association for Cancer Research, 2017-04) Adamik, Juraj; Jin, Shunqian; Sun, Quanhong; Zhang, Peng; Weiss, Kurt R.; Anderson, Judith L.; Silbermann, Rebecca; Roodman, G. David; Galson, Deborah L.; Medicine, School of Medicine
    In multiple myeloma, osteolytic lesions rarely heal because of persistent suppressed osteoblast differentiation resulting in a high fracture risk. Herein, chromatin immunoprecipitation analyses reveal that multiple myeloma cells induce repressive epigenetic histone changes at the Runx2 locus that prevent osteoblast differentiation. The most pronounced multiple myeloma-induced changes were at the Runx2-P1 promoter, converting it from a poised bivalent state to a repressed state. Previously, it was observed that multiple myeloma induces the transcription repressor GFI1 in osteoblast precursors, which correlates with decreased Runx2 expression, thus prompting detailed characterization of the multiple myeloma and TNFα-dependent GFI1 response element within the Runx2-P1 promoter. Further analyses reveal that multiple myeloma-induced GFI1 binding to Runx2 in osteoblast precursors and recruitment of the histone modifiers HDAC1, LSD1, and EZH2 is required to establish and maintain Runx2 repression in osteogenic conditions. These GFI1-mediated repressive chromatin changes persist even after removal of multiple myeloma. Ectopic GFI1 is sufficient to bind to Runx2, recruit HDAC1 and EZH2, increase H3K27me3 on the gene, and prevent osteogenic induction of endogenous Runx2 expression. Gfi1 knockdown in MC4 cells blocked multiple myeloma-induced recruitment of HDAC1 and EZH2 to Runx2, acquisition of repressive chromatin architecture, and suppression of osteoblast differentiation. Importantly, inhibition of EZH2 or HDAC1 activity in pre-osteoblasts after multiple myeloma exposure in vitro or in osteoblast precursors from patients with multiple myeloma reversed the repressive chromatin architecture at Runx2 and rescued osteoblast differentiation.Implications: This study suggests that therapeutically targeting EZH2 or HDAC1 activity may reverse the profound multiple myeloma-induced osteoblast suppression and allow repair of the lytic lesions.
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    GFI1-Dependent Repression of SGPP1 Increases Multiple Myeloma Cell Survival
    (MDPI, 2022-02-02) Petrusca, Daniela N.; Mulcrone, Patrick L.; Macar, David A.; Bishop, Ryan T.; Berdyshev, Evgeny; Suvannasankha, Attaya; Anderson, Judith L.; Sun, Quanhong; Auron, Philip E.; Galson, Deborah L.; Roodman, G. David; Medicine, School of Medicine
    Multiple myeloma (MM) remains incurable for most patients due to the emergence of drug resistant clones. Here we report a p53-independent mechanism responsible for Growth Factor Independence-1 (GFI1) support of MM cell survival by its modulation of sphingolipid metabolism to increase the sphingosine-1-phosphate (S1P) level regardless of the p53 status. We found that expression of enzymes that control S1P biosynthesis, SphK1, dephosphorylation, and SGPP1 were differentially correlated with GFI1 levels in MM cells. We detected GFI1 occupancy on the SGGP1 gene in MM cells in a predicted enhancer region at the 5' end of intron 1, which correlated with decreased SGGP1 expression and increased S1P levels in GFI1 overexpressing cells, regardless of their p53 status. The high S1P:Ceramide intracellular ratio in MM cells protected c-Myc protein stability in a PP2A-dependent manner. The decreased MM viability by SphK1 inhibition was dependent on the induction of autophagy in both p53WT and p53mut MM. An autophagic blockade prevented GFI1 support for viability only in p53mut MM, demonstrating that GFI1 increases MM cell survival via both p53WT inhibition and upregulation of S1P independently. Therefore, GFI1 may be a key therapeutic target for all types of MM that may significantly benefit patients that are highly resistant to current therapies.
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    Growth factor independence 1 expression in myeloma cells enhances their growth, survival, and osteoclastogenesis
    (Biomed Central, 2018-10-04) Petrusca, Daniela N.; Toscani, Denise; Wang, Feng-Ming; Park, Cheolkyu; Crean, Colin D.; Anderson, Judith L.; Marino, Silvia; Mohammad, Khalid S.; Zhou, Dan; Silbermann, Rebecca; Sun, Quanhong; Kurihara, Noriyoshi; Galson, Deborah L.; Giuliani, Nicola; Roodman, G. David; Medicine, School of Medicine
    BACKGROUND: In spite of major advances in treatment, multiple myeloma (MM) is currently an incurable malignancy due to the emergence of drug-resistant clones. We previously showed that MM cells upregulate the transcriptional repressor, growth factor independence 1 (Gfi1), in bone marrow stromal cells (BMSCs) that induces prolonged inhibition of osteoblast differentiation. However, the role of Gfi1 in MM cells is unknown. METHODS: Human primary CD138+ and BMSC were purified from normal donors and MM patients' bone marrow aspirates. Gfi1 knockdown and overexpressing cells were generated by lentiviral-mediated shRNA. Proliferation/apoptosis studies were done by flow cytometry, and protein levels were determined by Western blot and/or immunohistochemistry. An experimental MM mouse model was generated to investigate the effects of MM cells overexpressing Gfi1 on tumor burden and osteolysis in vivo. RESULTS: We found that Gfi1 expression is increased in patient's MM cells and MM cell lines and was further increased by co-culture with BMSC, IL-6, and sphingosine-1-phosphate. Modulation of Gfi1 in MM cells had major effects on their survival and growth. Knockdown of Gfi1 induced apoptosis in p53-wt, p53-mutant, and p53-deficient MM cells, while Gfi1 overexpression enhanced MM cell growth and protected MM cells from bortezomib-induced cell death. Gfi1 enhanced cell survival of p53-wt MM cells by binding to p53, thereby blocking binding to the promoters of the pro-apoptotic BAX and NOXA genes. Further, Gfi1-p53 binding could be blocked by HDAC inhibitors. Importantly, inoculation of MM cells overexpressing Gfi1 in mice induced increased bone destruction, increased osteoclast number and size, and enhanced tumor growth. CONCLUSIONS: These results support that Gfi1 plays a key role in MM tumor growth, survival, and bone destruction and contributes to bortezomib resistance, suggesting that Gfi1 may be a novel therapeutic target for MM.
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    Increased IL-6 expression in osteoclasts is necessary but not sufficient for the development of Paget's disease of bone
    (Wiley, 2014-06) Teramachi, Jumpei; Zhou, Hua; Subler, Mark A.; Kitagawa, Yukiko; Galson, Deborah L.; Dempster, David W.; Windle, Jolene J.; Kurihara, Noriyoshi; Roodman, G. David; Department of Medicine, IU School of Medicine
    Measles virus nucleocapsid protein (MVNP) expression in osteoclasts (OCLs) and mutation of the SQSTM1 (p62) gene contribute to the increased OCL activity in Paget's disease (PD). OCLs expressing MVNP display many of the features of PD OCLs. Interleukin-6 (IL-6) production is essential for the pagetic phenotype, because transgenic mice with MVNP targeted to OCLs develop pagetic OCLs and lesions, but this phenotype is absent when MVNP mice are bred to IL-6(-/-) mice. In contrast, mutant p62 expression in OCL precursors promotes receptor activator of NF-κB ligand (RANKL) hyperresponsivity and increased OCL production, but OCLs that form have normal morphology, are not hyperresponsive to 1,25-dihydroxyvitamin D3 (1,25-(OH)2 D3 ), nor produce elevated levels of IL-6. We previously generated p62(P394L) knock-in mice (p62KI) and found that although OCL numbers were increased, the mice did not develop pagetic lesions. However, mice expressing both MVNP and p62KI developed more exuberant pagetic lesions than mice expressing MVNP alone. To examine the role of elevated IL-6 in PD and determine if MVNP mediates its effects primarily through elevation of IL-6, we generated transgenic mice that overexpress IL-6 driven by the tartrate-resistant acid phosphatase (TRAP) promoter (TIL-6 mice) and produce IL-6 at levels comparable to MVNP mice. These were crossed with p62KI mice to determine whether IL-6 overexpression cooperates with mutant p62 to produce pagetic lesions. OCL precursors from p62KI/TIL-6 mice formed greater numbers of OCLs than either p62KI or TIL-6 OCL precursors in response to 1,25-(OH)2 D3 . Histomorphometric analysis of bones from p62KI/TIL-6 mice revealed increased OCL numbers per bone surface area compared to wild-type (WT) mice. However, micro-quantitative CT (µQCT) analysis did not reveal significant differences between p62KI/TIL-6 and WT mice, and no pagetic OCLs or lesions were detected in vivo. Thus, increased IL-6 expression in OCLs from p62KI mice contributes to increased responsivity to 1,25-(OH)2 D3 and increased OCL numbers, but is not sufficient to induce Paget's-like OCLs or bone lesions in vivo.
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    Osteoblast suppression in multiple myeloma bone disease
    (Elsevier, 2018-09-15) Adamik, Juraj; Galson, Deborah L.; Roodman, G. David; Medicine, School of Medicine
    Multiple myeloma (MM) is the most frequent cancer to involve the skeleton with patients developing osteolytic bone lesions due to hyperactivation of osteoclasts and suppression of BMSCs differentiation into functional osteoblasts. Although new therapies for MM have greatly improved survival, MM remains incurable for most patients. Despite the major advances in current anti-MM and anti-resorptive treatments that can significantly improve osteolytic bone lysis, many bone lesions can persist even after therapeutic remission of active disease. Bone marrow mesenchymal stem cells (BMSCs) from MM patients are phenotypically distinct from their healthy counterparts and the mechanisms associated with the long-term osteogenic suppression are largely unknown. In this review we will highlight recent results of transcriptomic profiling studies that provide new insights into the establishment and maintenance of the persistent pathological alterations in MM-BMSCs that occur in MM. We will we discuss the role of genomic instabilities and senescence in propagating the chronically suppressed state and pro-inflammatory phenotype associated with MM-BMSCs. Lastly we describe the role of epigenetic-based mechanisms in regulating osteogenic gene expression to establish and maintain the pro-longed suppression of MM-BMSC differentiation into functional OBs.
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    The Role of Semaphorin 4D in Bone Remodeling and Cancer Metastasis
    (Frontiers Media, 2018-06-19) Lontos, Konstantinos; Adamik, Juraj; Tsagianni, Anastasia; Galson, Deborah L.; Chirgwin, John M.; Suvannasankha, Attaya; Medicine, School of Medicine
    Semaphorin 4D (Sema4D; CD100) is a transmembrane homodimer 150-kDa glycoprotein member of the Semaphorin family. Semaphorins were first identified as chemorepellants that guide neural axon growth. Sema4D also possesses immune regulatory activity. Recent data suggest other Sema4D functions: inactivation of platelets, stimulation of angiogenesis, and regulation of bone formation. Sema4D is a coupling factor expressed on osteoclasts that inhibits osteoblast differentiation. Blocking Sema4D may, therefore, be anabolic for bone. Sema4D and its receptor Plexin-B1 are commonly dysregulated in cancers, suggesting roles in cancer progression, invasion, tumor angiogenesis, and skeletal metastasis. This review focuses on Sema4D in bone and cancer biology and the molecular pathways involved, particularly Sema4D-Plexin-B1 signaling crosstalk between cancer cells and the bone marrow microenvironment-pertinent areas since a humanized Sema4D-neutralizing antibody is now in early phase clinical trials in cancers and neurological disorders.
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    Role of Sphingolipids in Multiple Myeloma Progression, Drug Resistance, and Their Potential as Therapeutic Targets
    (Frontiers Media, 2022-06-08) Petrusca, Daniela N.; Lee, Kelvin P.; Galson, Deborah L.; Medicine, School of Medicine
    Multiple myeloma (MM) is an incapacitating hematological malignancy characterized by accumulation of cancerous plasma cells in the bone marrow (BM) and production of an abnormal monoclonal protein (M-protein). The BM microenvironment has a key role in myeloma development by facilitating the growth of the aberrant plasma cells, which eventually interfere with the homeostasis of the bone cells, exacerbating osteolysis and inhibiting osteoblast differentiation. Recent recognition that metabolic reprograming has a major role in tumor growth and adaptation to specific changes in the microenvironmental niche have led to consideration of the role of sphingolipids and the enzymes that control their biosynthesis and degradation as critical mediators of cancer since these bioactive lipids have been directly linked to the control of cell growth, proliferation, and apoptosis, among other cellular functions. In this review, we present the recent progress of the research investigating the biological implications of sphingolipid metabolism alterations in the regulation of myeloma development and its progression from the pre-malignant stage and discuss the roles of sphingolipids in in MM migration and adhesion, survival and proliferation, as well as angiogenesis and invasion. We introduce the current knowledge regarding the role of sphingolipids as mediators of the immune response and drug-resistance in MM and tackle the new developments suggesting the manipulation of the sphingolipid network as a novel therapeutic direction for MM.