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Oncolytic virotherapy represents an innovative and promising approach for the treatment of cancer, including multiple myeloma (MM), a currently incurable plasma cell (PC) neoplasm. Despite the advances that new therapies, particularly immunotherapy, have been made, relapses still occur in MM patients, highlighting the medical need for new treatment options. Oncolytic viruses (OVs) preferentially infect and destroy cancer cells, exerting a direct and/or indirect cytopathic effect, combined with a modulation of the tumor microenvironment leading to an activation of the immune system. Both naturally occurring and genetically modified viruses have demonstrated significant preclinical effects against MM cells. Currently, the OVs genetically modified measles virus strains, reovirus, and vesicular stomatitis virus are employed in clinical trials for MM. Nevertheless, significant challenges remain, including the efficiency of the virus delivery to the tumor, overcoming antiviral immune responses, and the specificity of the virus for MM cells. Different strategies are being explored to optimize OV therapy, including combining it with standard treatments and targeted therapies to enhance efficacy. This review will provide a comprehensive analysis of the mechanism of action of the different OVs, and preclinical and clinical evidence, focusing on the role of oncolytic virotherapy as a new possible immunotherapeutic approach also in combination with the current therapeutic armamentarium and underlying the future directions in the context of MM treatments., Competing Interests: NG received research funding and honoraria from Amgen, Bristol-Myers Squibb, Takeda, Celgene, Millennium Pharmaceuticals, and Janssen Pharmaceuticals. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Raimondi, Vescovini, Dessena, Donofrio, Storti and Giuliani.)

DNA damage resistance is a major barrier to effective DNA-damaging therapy in multiple myeloma (MM). To discover mechanisms through which MM cells overcome DNA damage, we investigate how MM cells become resistant to antisense oligonucleotide (ASO) therapy targeting Interleukin enhancer binding factor 2 (ILF2), a DNA damage regulator that is overexpressed in 70% of MM patients whose disease has progressed after standard therapies have failed. Here, we show that MM cells undergo adaptive metabolic rewiring to restore energy balance and promote survival in response to DNA damage activation. Using a CRISPR/Cas9 screening strategy, we identify the mitochondrial DNA repair protein DNA2, whose loss of function suppresses MM cells' ability to overcome ILF2 ASO-induced DNA damage, as being essential to counteracting oxidative DNA damage. Our study reveals a mechanism of vulnerability of MM cells that have an increased demand for mitochondrial metabolism upon DNA damage activation., (© 2024. The Author(s).)

Multiple myeloma (MM) is a monoclonal gammopathy characterized by biological heterogeneity and unregulated proliferation of plasma cells (PCs) in bone marrow (BM). MM is a multistep process based on genomic instability, epigenetic dysregulation and a tight cross-talk with the BM microenvironment that plays a pivotal role supporting the proliferation, survival, drug-resistance and homing of PCs. The BM microenvironment consists of a hematopoietic and a non-hematopoietic compartment, which cooperate to create a tumor environment. Among the non-hematopoietic component, mesenchymal stromal cells (MSCs) and osteoblasts (OBs) appear transcriptionally and functionally different in MM patients compared to healthy donors (HDs) and to patients with pre-malignant monoclonal gammopathies. Alterations of both MSCs and OBs underly the osteolytic lesions that characterize myeloma-associated bone disease. In this review, we will discuss the different characteristics of MSCs and OBs in MM patients, analyzing the transcriptome, the deregulated molecular pathways and the role performed by miRNAs and exosome in the pathophysiology of MM.

Multiple myeloma (MM) is a hematological malignancy characterized by the accumulation of malignant plasma cells (PCs) into the bone marrow (BM). The complex interaction between the BM microenvironment and MM PCs can lead to severe impairment of bone remodeling. Indeed, the BM microenvironment exerts a critical role in the survival of malignant PCs. Growing evidence indicates that MM cells have several metabolic features including enhanced glycolysis and an increase in lactate production through the upregulation of glucose transporters and enzymes. More recently, it has been reported that MM cells arehighly glutamine addicted. Interestingly, these metabolic changes in MM cells may affect BM microenvironment cells by altering the differentiation process of osteoblasts from mesenchymal stromal cells. The identification of glutamine metabolism alterations in MM cells and bone microenvironment may provide a rationale to design new therapeutic approaches and diagnostic tools. The osteolytic lesions are the most frequent clinical features in MM patients, often characterized by pathological fractures and acute pain. The use of the newer imaging techniques such as Magnetic Resonance Imaging (MRI) and combined Positron Emission Tomography (PET) and Computerized Tomography (CT) has been introduced into clinical practice to better define the skeletal involvement. Currently, the PET/CT with 18 F-fluorodeoxyglucose (FDG) is the diagnostic gold standard to detect active MM bone disease due to the high glycolytic activity of MM cells. However, new tracers are actively under investigation because a portion of MM patients remains negative at the skeletal level by 18 F-FDG. In this review, we will summarize the existing knowledge on the metabolic alterations of MM cells considering their impact on the BM microenvironment cells and particularly in the subsequent formation of osteolytic bone lesions. Based on this, we will discuss the identification of possible new druggable targets and the use of novel metabolic targets for PET imaging in the detection of skeletal lesions, in the staging and treatment response of MM patients., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Raimondi, Toscani, Marchica, Burroughs-Garcia, Storti and Giuliani.)

The humoral and cellular response to SARS-CoV-2 mRNA full vaccination and booster dose as well as the impact of the spike variants, including Omicron, are still unclear in patients with multiple myeloma (MM) and those with pre-malignant monoclonal gammopathies. In this study, involving 40 patients, we found that MM patients with relapsed-refractory disease (MMR) had reduced spike-specific antibody levels and neutralizing titers after SARS-CoV-2 vaccination. The five analyzed variants, remarkably Omicron, had a significant negative impact on the neutralizing ability of the vaccine-induced antibodies in all patients with MM and smoldering MM. Moreover, lower spike-specific IL-2-producing CD4 + T cells and reduced cytotoxic spike-specific IFN-γ and TNF-α-producing CD8 + T cells were found in MM patients as compared to patients with monoclonal gammopathy of undetermined significance. We found that a heterologous booster immunization improved SARS-CoV-2 spike humoral and cellular responses in newly diagnosed MM (MMD) patients and in most, but not all, MMR patients. After the booster dose, a significant increase of the neutralizing antibody titers against almost all the analyzed variants was achieved in MMD. However, in MMR patients, Omicron retained a negative impact on neutralizing ability, suggesting further approaches to potentiating the effectiveness of SARS-CoV-2 vaccination in these patients., Competing Interests: The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflicts with the subject matter or materials discussed in the manuscript., (© 2022 The Author(s). Published with license by Taylor & Francis Group, LLC.)

Multiple myeloma (MM) is a blood cancer that derives from plasma cells (PCs), which will accumulate in the bone marrow (BM). Over time, several drugs have been developed to treat this disease that is still uncurable. The therapies used to treat the disease target immune activity, inhibit proteasome activity, and involve the use of monoclonal antibodies. However, MM is a highly heterogeneous disease, in fact, there are several mutations in signaling pathways that are particularly important for MM cell biology and that are possible therapeutic targets. Indeed, some studies suggest that MM is driven by mutations within the rat sarcoma virus ( RAS ) signaling cascade, which regulates cell survival and proliferation. The RAS /proto-oncogene, serine/threonine kinase ( RAF )/mitogen-activated extracellular signal-regulated kinase ( ERK ) kinase ( MEK )/ ERK signaling pathway is deregulated in several cancers, for which drugs have been developed to inhibit these pathways. In addition to the signaling pathways, the disease implements mechanisms to ensure the survival and consequently a high replicative capacity. This strategy consists in the deregulation of apoptosis. In particular, some cases of MM show overexpression of anti-apoptotic proteins belonging to the B cell lymphoma 2 ( BCL-2 ) family that represent a possible druggable target. Venetoclax is an anti- BCL-2 molecule used in hematological malignancies that may be used in selected MM patients based on their molecular profile. We focused on the possible effects in MM of off-label drugs that are currently used for other cancers with the same molecular characteristics. Their use, combined with the current treatments, could be a good strategy against MM., Competing Interests: NG received research funding and honoraria from Amgen, Bristol Mayers Squibb, Celgene, Millenium Pharmaceutical, GSK, Takeda, and Janssen Pharmaceutical. The remaining authors declare that they have no conflicts of interest., (© The Author(s) 2022.)

Monoclonal antibodies (mAbs) directed against antigen-specific of multiple myeloma (MM) cells have Fc-dependent immune effector mechanisms, such as complement-dependent cytotoxicity (CDC), antibody-dependent cellular cytotoxicity (ADCC), and antibody-dependent cellular phagocytosis (ADCP), but the choice of the antigen is crucial for the development of effective immuno-therapy in MM. Recently new immunotherapeutic options in MM patients have been developed against different myeloma-related antigens as drug conjugate-antibody, bispecific T-cell engagers (BiTEs) and chimeric antigen receptor (CAR)-T cells. In this review, we will highlight the mechanism of action of immuno-therapy currently available in clinical practice to target CD38, SLAMF7, and BCMA, focusing on the biological role of the targets and on mechanisms of actions of the different immunotherapeutic approaches underlying their advantages and disadvantages with critical review of the literature data., Competing Interests: NG received research funding and honoraria from Amgen, Bristol Mayers Squibb, Celgene, Millenium Pharmaceutical, and Janssen Pharmaceutical. AR and FR received research funding and honoraria from Amgen. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Romano, Storti, Marchica, Scandura, Notarfranchi, Craviotto, Di Raimondo and Giuliani.)

Multiple myeloma (MM) is characterized by an accumulation of malignant plasma cells (PCs) in the bone marrow (BM). The amplification of 1q21 is one of the most common cytogenetic abnormalities occurring in around 40% of de novo patients and 70% of relapsed/refractory MM. Patients with this unfavorable cytogenetic abnormality are considered to be high risk with a poor response to standard therapies. The gene(s) driving amplification of the 1q21 amplicon has not been fully studied. A number of clear candidates are under investigation, and some of them ( IL6R , ILF2 , MCL-1 , CKS1B and BCL9 ) have been recently proposed to be potential drivers of this region. However, much remains to be learned about the biology of the genes driving the disease progression in MM patients with 1q21 amp. Understanding the mechanisms of these genes is important for the development of effective targeted therapeutic approaches to treat these patients for whom effective therapies are currently lacking. In this paper, we review the current knowledge about the pathological features, the mechanism of 1q21 amplification, and the signal pathway of the most relevant candidate genes that have been suggested as possible therapeutic targets for the 1q21 amplicon.

Background: The PD-1/PD-L1 axis has recently emerged as an immune checkpoint that controls antitumor immune responses also in hematological malignancies. However, the use of anti-PD-L1/PD-1 antibodies in multiple myeloma (MM) patients still remains debated, at least in part because of discordant literature data on PD-L1/PD-1 expression by MM cells and bone marrow (BM) microenvironment cells. The unmet need to identify patients which could benefit from this therapeutic approach prompts us to evaluate the BM expression profile of PD-L1/PD-1 axis across the different stages of the monoclonal gammopathies., Methods: The PD-L1/PD-1 axis was evaluated by flow cytometry in the BM samples of a total cohort of 141 patients with monoclonal gammopathies including 24 patients with Monoclonal Gammopathy of Undetermined Significance (MGUS), 38 patients with smoldering MM (SMM), and 79 patients with active MM, including either newly diagnosed or relapsed-refractory patients. Then, data were correlated with the main immunological and clinical features of the patients., Results: First, we did not find any significant difference between MM and SMM patients in terms of PD-L1/PD-1 expression, on both BM myeloid (CD14 + ) and lymphoid subsets. On the other hand, PD-L1 expression by CD138 + MM cells was higher in both SMM and MM as compared to MGUS patients. Second, the analysis on the total cohort of MM and SMM patients revealed that PD-L1 is expressed at higher level in CD14 + CD16 + non-classical monocytes compared with classical CD14 + CD16 - cells, independently from the stage of disease. Moreover, PD-L1 expression on CD14 + cells was inversely correlated with BM serum levels of the anti-tumoral cytokine, IL-27. Interestingly, relapsed MM patients showed an inverted CD4 + /CD8 + ratio along with high levels of pro-tumoral IL-6 and a positive correlation between %CD14 + PD-L1 + and %CD8 + PD-1 + cells as compared to both SMM and newly diagnosed MM patients suggesting a highly compromised immune-compartment with low amount of CD4 + effector cells., Conclusions: Our data indicate that SMM and active MM patients share a similar PD-L1/PD-1 BM immune profile, suggesting that SMM patients could be an interesting target for PD-L1/PD-1 inhibition therapy, in light of their less compromised and more responsive immune-compartment., Competing Interests: NG received research funding and honoraria from Amgen, Bristol Mayers Squibb, Celgene, Millenium Pharmaceutical, and Janssen Pharmaceutical. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Costa, Vescovini, Marchica, Storti, Notarfranchi, Dalla Palma, Toscani, Burroughs-Garcia, Catarozzo, Sammarelli and Giuliani.)

The emerging role of the PD-1/PD-L1 axis in MM immune-microenvironment has been highlighted by several studies. However, discordant data have been reported on PD-1/PD-L1 distribution within the bone marrow (BM) microenvironment of patients with monoclonal gammopathies. In addition, the efficacy of PD-1/PD-L1 blockade as a therapeutic strategy to reverse myeloma immune suppression and inhibit myeloma cell survival still remains unknown. Recent data suggest that, among the potential mechanisms behind the lack of responsiveness or resistance to anti-PD-L1/PD-1 antibodies, the CD38 metabolic pathways involving the immune-suppressive factor, adenosine, could play an important role. This review summarizes the available data on PD-1/PD-L1 expression in patients with MM, reporting the main mechanisms of regulation of PD-1/PD-L1 axis. The possible link between the CD38 and PD-1/PD-L1 pathways is also reported, highlighting the rationale for the potential use of a combined therapeutic approach with CD38 blocking agents and anti-PD-1/PD-L1 antibodies in order to improve their anti-tumoral effect in MM patients.

Multiple myeloma (MM) cells consume huge amounts of glutamine and, as a consequence, the amino acid concentration is lower-than-normal in the bone marrow (BM) of MM patients. Here we show that MM-dependent glutamine depletion induces glutamine synthetase in stromal cells, as demonstrated in BM biopsies of MM patients, and reproduced in vitro by co-culturing human mesenchymal stromal cells (MSCs) with MM cells. Moreover, glutamine depletion hinders osteoblast differentiation of MSCs, which is also severely blunted by the spent, low-glutamine medium of MM cells, and rescued by glutamine restitution. Glutaminase and the concentrative glutamine transporter SNAT2 are induced during osteoblastogenesis in vivo and in vitro, and both needed for MSCs differentiation, pointing to enhanced the requirement for the amino acid. Osteoblastogenesis also triggers the induction of glutamine-dependent asparagine synthetase (ASNS), and, among non-essential amino acids, asparagine rescues differentiation of glutamine-starved MSCs, by restoring the transcriptional profiles of differentiating MSCs altered by glutamine starvation. Thus, reduced asparagine availability provides a mechanistic link between MM-dependent Gln depletion in BM and impairment of osteoblast differentiation. Inhibition of Gln metabolism in MM cells and supplementation of asparagine to stromal cells may, therefore, constitute novel approaches to prevent osteolytic lesions in MM.

The monoclonal antibodies (mAbs) have significantly changed the treatment of multiple myeloma (MM) patients. However, despite their introduction, MM remains an incurable disease. The mAbs currently used for MM treatment were developed with different mechanisms of action able to target antigens, such as cluster of differentiation 38 (CD38) and SLAM family member 7 (SLAMF7) expressed by both, MM cells and the immune microenvironment cells. In this review, we focused on the mechanisms of action of the main mAbs approved for the therapy of MM, and on the possible novel approaches to improve MM cell killing by mAbs. Actually, the combination of anti-CD38 or anti-SLAMF7 mAbs with the immunomodulatory drugs significantly improved the clinical effect in MM patients. On the other hand, pre-clinical evidence indicates that different approaches may increase the efficacy of mAbs. The use of trans-retinoic acid, the cyclophosphamide or the combination of anti-CD47 and anti-CD137 mAbs have given the rationale to design these types of combinations therapies in MM patients in the future. In conclusion, a better understanding of the mechanism of action of the mAbs will allow us to develop novel therapeutic approaches to improve their response rate and to overcome their resistance in MM patients.

A deep elucidation of the mechanisms of action of anti-CD38 monoclonal antibodies (mAbs), such as daratumumab (DARA), is required to identify patients with multiple myeloma (MM) who are more responsive to this treatment. In the present study, an autologous ex vivo approach was established, focussing on the role of the monocytes in the anti CD38-mediated killing of MM cells. In bone marrow (BM) samples from 29 patients with MM, we found that the ratio between monocytes (CD14 + ) and MM cells (CD138 + ) influences the response to DARA. Further, the exposure of the BM samples to DARA is followed by the formation of a CD138 + CD14 + double-positive (DP) population, that quantitatively correlates with the anti-MM cells killing. These effects were dependent on the presence of a CD14 + CD16 + monocyte subset and on high CD16 expression levels. Lastly, the addition of a mAb neutralising the CD47/signal-regulatory protein α (SIRPα) axis was able to increase the killing mediated by DARA. The effects were observed only in coincidence with high CD14 + :CD138 + ratio, with a significant presence of the DP population and were correlated with CD16 expression. In conclusion, the present study underlines the critical role of the CD16 + monocytes in DARA anti-MM killing effects and gives a rationale to test the combination of an anti-CD47 mAb with anti-CD38 mAbs., (© 2020 British Society for Haematology and John Wiley & Sons Ltd.)

Background: The oncolytic viruses have shown promising results for the treatment of multiple myeloma. However, the use of human viruses is limited by the patients' antiviral immune response. In this study, we investigated an alternative oncolytic strategy using non-human pathogen viruses as the bovine viral diarrhea virus (BVDV) that were able to interact with CD46., Methods: We treated several human myeloma cell lines and non-myeloma cell lines with BVDV to evaluate the expression of CD46 and to study the effect on cell viability by flow cytometry. The possible synergistic effect of bortezomib in combination with BVDV was also tested. Moreover, we infected the bone marrow mononuclear cells obtained from myeloma patients and we checked the BVDV effect on different cell populations, defined by CD138, CD14, CD3, CD19, and CD56 expression evaluated by flow cytometry. Finally, the in vivo BVDV effect was tested in NOD-SCID mice injected subcutaneously with myeloma cell lines., Results: Human myeloma cells were selectively sensitive to BVDV treatment with an increase of cell death and, consequently, of apoptotic markers. Consistently, bone marrow mononuclear cells isolated from myeloma patients treated with BVDV, showed a significant selective decrease of the percentage of viable CD138 + cells. Interestingly, bortezomib pre-treatment significantly increased the cytotoxic effect of BVDV in myeloma cell lines with a synergistic effect. Finally, the in vitro data were confirmed in an in vivo myeloma mouse model showing that BVDV treatment significantly reduced the tumoral burden compared to the vehicle., Conclusions: Overall, our data indicate, for the first time, a direct oncolytic effect of the BVDV in human myeloma cells suggesting its possible use as novel alternative anti-myeloma virotherapy strategy.

Genomic analysis could contribute to a better understanding of the biological determinants of the evolution of multiple myeloma (MM) precursor disease and an improved definition of high-risk patients. To assess the feasibility and value of next-generation sequencing approaches in an asymptomatic setting, we performed a targeted gene mutation analysis and a genome-wide assessment of copy number alterations (CNAs) by ultra-low-pass whole genome sequencing (ULP-WGS) in six patients with monoclonal gammopathy of undetermined significance and 25 patients with smoldering MM (SMM). Our comprehensive genomic characterization highlighted heterogeneous but substantial values of the tumor fraction, especially in SMM; a rather high degree of genomic complexity, in terms of both mutations and CNAs, and inter-patient variability; a higher incidence of gene mutations and CNAs in SMM, confirming ongoing evolution; intraclonal heterogeneity; and instances of convergent evolution. ULP-WGS of these patients proved effective in revealing the marked genome-wide level of their CNAs, most of which are not routinely investigated. Finally, the analysis of our small SMM cohort suggested that chr(8p) deletions, the DNA tumor fraction, and the number of alterations may have clinical relevance in the progression to overt MM. Although validation in larger series is mandatory, these findings highlight the promising impact of genomic approaches in the clinical management of SMM.

Introduction : Multiple myeloma (MM) is characterized by the high tendency to relapse and develop drug resistance. Areas covered : This review focused on the main novel targets identified to design drugs for the treatment of relapsing MM patients. CD38 and SLAMF7 are the main surface molecules leading to the development of monoclonal antibodies (mAbs) recently approved for the treatment of relapsing MM patients. B cell maturation antigen (BCMA) is a suitable target for antibody-drug conjugates, bispecific T cell engager mAbs and Chimeric Antigen Receptor (CAR)-T cells. Moreover, the programmed cell death protein 1 (PD)-1/PD-Ligand (PD-L1) expression profile by MM cells and their microenvironment and the use of immune checkpoints inhibitors in MM patients are reported. Finally, the role of histone deacetylase (HDAC), B cell lymphoma (BCL)-2 family proteins and the nuclear transport protein exportin 1 (XPO1) as novel targets are also underlined. The clinical results of the new inhibitors in relapsing MM patients are discussed. Expert opinion : CD38, SLAMF7, and BCMA are the main targets for different immunotherapeutic approaches. Selective inhibitors of HDAC6, BCL-2, and XPO1 are new promising compounds under clinical investigation in relapsing MM patients.

C-X3-C motif chemokine ligand 1 (CX3CL1)/fractalkine is a chemokine released after cleavage by two metalloproteases, ADAM metallopeptidase domain 10 (ADAM10) and ADAM metallopeptidase domain 17 (ADAM17), involved in inflammation and angiogenesis in the cancer microenvironment. The role of the CX3CL1/ C-X3-C motif chemokine receptor 1(CX3CR1) axis in the multiple myeloma (MM) microenvironment is still unknown. Firstly, we analyzed bone marrow (BM) plasma levels of CX3CL1 in 111 patients with plasma cell disorders including 70 with active MM, 25 with smoldering myeloma (SMM), and 16 with monoclonal gammopathy of undetermined significance (MGUS). We found that BM CX3CL1 levels were significantly increased in MM patients compared to SMM and MGUS and correlated with BM microvessel density. Secondly, we explored the source of CX3CL1 in MM and BM microenvironment cells. Primary CD138⁺ cells did not express CXC3L1 but up-regulated its production by endothelial cells (ECs) through the involvement of tumor necrosis factor alpha (TNFα). Lastly, we demonstrated the presence of CX3CR1 on BM CD14⁺CD16⁺ monocytes of MM patients and on ECs, but not on MM cells. The role of CX3CL1 in MM-induced angiogenesis was finally demonstrated in both in vivo chick embryo chorioallantoic membrane and in vitro angiogenesis assays. Our data indicate that CX3CL1, present at a high level in the BM of MM patients, is a new player of the MM microenvironment involved in MM-induced angiogenesis., Competing Interests: The authors declare no conflict of interest.

Multiple myeloma osteolytic disease is caused by an uncoupled bone-remodelling process with an increased osteoclast activity. Disease development relies on interactions between myeloma cells and bone marrow stromal cells. Recent findings suggest a role for glycan-binding proteins in myeloma microenvironment. Here, we investigated lectins involved in osteoclastogenesis and their role in myeloma bone disease. Microarray data analysis showed a lower expression of galectin-1 (gal-1) in mature osteoclasts compared to monocytic progenitor cells, confirmed at the RNA and protein levels in osteoclast cultures. Confocal microscopy showed that gal-1 localised predominantly in the sealing zone of mature osteoclasts. Although equal differentiated-osteoclast numbers, gal-1 -/- osteoclasts showed a higher resorption activity compared to wild-type controls. Micro-computed tomography showed an aberrant bone phenotype with decreased bone densities in gal-1 -/- mice. In vivo, tumour progression was faster in gal-1 -/- mice and associated with a marked bone loss. Additionally, myeloma cells were found to decrease gal-1 expression in osteoclasts. Our results demonstrate that galectin-1 regulates osteoclast activity with an increased resorption by gal-1 -/- osteoclasts and decreased bone densities in gal-1 -/- mice. We observed an enhanced tumour development in gal-1 -/- mice compared to wild-type mice, suggesting that galectin-1 has a functional role in stromal cells in myeloma microenvironment.

The association between Neurofibromatosis type I (NF1) and multiple myeloma (MM), a plasma cell, dyscrasia is very rare. Here we put to the attention of the scientific community two new cases. The first one is a patient with active MM whereas the second with smoldering MM. Both patients present typical features of NF1 but skeletal alterations were present only in the second case including dysplasia, marked scoliosis and osteoporosis. MM osteolytic lesions were absent in both patients. In addition to the clinical diagnosis of NF1, a molecular testing for NF1 gene mutations has been performed finding that patient one was heterozygous for the c.6855C>A (Tyr2285Ter) mutation, while patient two was heterozygous for the c.7838dupC (Lys2614GlufsTer20) mutation. The two mutations were diagnosed both in genomic DNA from peripheral blood and from MM cells. The potential link between NF1 mutation and the increased risk of MM is discussed in the report., Competing Interests: Conflict of interest: the authors declare no potential conflict of interest.

Introduction: Bone destruction is the hallmark of multiple myeloma (MM). About 80% of MM patients at diagnosis presents myeloma bone disease (MBD) leading to bone pain and pathological fractures, significantly affecting patients' quality of life. Bisphosphonates are the treatment of choice for MBD, but osteolytic lesions remain a critical issue in the current management of MM patients. Several studies clarified the mechanisms involved in MM-induced osteoclast formation and activation, leading to the identification of new possible targets and the development of better bone-directed therapies, that are discussed in this review. Areas covered: This review summarizes the latest advances in the knowledge of the pathophysiology of the osteoclast formation and activation induced by MM cells, and the new therapeutic targets identified. Recently, neutralizing antibodies (i.e. denosumab, siltuximab, daratumumab), as well as recombinant fusion proteins, and receptor molecular inhibitors, have been developed to block these targets. Clinical trials testing their anti-MBD potential are ongoing. The emerging role of exosomes and microRNAs in the regulation of osteoclast differentiation has been also discussed. Expert commentary: Although further studies are needed to arrive at a clinical approving, the basis for the development of better bone-directed therapies has been established.

Galectins are a family of lectins that bind β-galactose-containing glycoconjugates and are characterized by carbohydrate-recognition domains (CRDs). Galectins exploit several biological functions, including angiogenesis, regulation of immune cell activities and cell adhesion, in both physiological and pathological processes, as tumor progression. Multiple myeloma (MM) is a plasma cell (PC) malignancy characterized by the tight adhesion between tumoral PCs and bone marrow (BM) microenvironment, leading to the increase of PC survival and drug resistance, MM-induced neo-angiogenesis, immunosuppression and osteolytic bone lesions. In this review, we explore the expression profiles and the roles of galectin-1, galectin-3, galectin-8 and galectin-9 in the pathophysiology of MM. We focus on the role of these lectins in the interplay between MM and BM microenvironment cells showing their involvement in MM progression mainly through the regulation of PC survival and MM-induced angiogenesis and osteoclastogenesis. The translational impact of these pre-clinical pieces of evidence is supported by recent data that indicate galectins could be new attractive targets to block MM cell growth in vivo and by the evidence that the expression levels of LGALS1 and LGALS8 , genes encoding for galectin-1 and galectin-8 respectively, correlate to MM patients' survival., Competing Interests: The authors declare no conflict of interest.

Amplification of 1q21 occurs in approximately 30% of de novo and 70% of relapsed multiple myeloma (MM) and is correlated with disease progression and drug resistance. Here, we provide evidence that the 1q21 amplification-driven overexpression of ILF2 in MM promotes tolerance of genomic instability and drives resistance to DNA-damaging agents. Mechanistically, elevated ILF2 expression exerts resistance to genotoxic agents by modulating YB-1 nuclear localization and interaction with the splicing factor U2AF65, which promotes mRNA processing and the stabilization of transcripts involved in homologous recombination in response to DNA damage. The intimate link between 1q21-amplified ILF2 and the regulation of RNA splicing of DNA repair genes may be exploited to optimize the use of DNA-damaging agents in patients with high-risk MM., (Copyright © 2017 Elsevier Inc. All rights reserved.)

The use of Lenalidomide (LEN), to reverse tumor-mediated immune suppression and amplify multiple myeloma-specific immunity is currently being explored. Particularly, LEN effects on dendritic cells (DCs) are still unclear. In this study, we investigated the potential effect of LEN on DC differentiation and activity. DCs were differentiated either from CD14 + cells obtained from patients with multiple myeloma or from a human monocytic cell line. LEN, at the concentration range reached in vivo , significantly increased the median intensity expression of HLA-DR, CD86 and CD209 by DCs derived from both bone marrow and peripheral myeloma monocytes and enhanced the production of Interleukin-8, C-C motif chemokine ligand (CCL) 2, CCL5 and tumor necrosis factor-α. Consistently, LEN pre-treated DCs showed an increased ability to stimulate autologous CD3 + cell proliferation. LEN effect on dendritic differentiation was associated with the degradation of the Cereblon-related factors Ikaros and Aiolos. Moreover, we showed that LEN also blunted mesenchymal stromal cell inhibitory effect on dendritic differentiation, inhibiting Casein Kinase-1α levels. Finally, in vitro data were confirmed in ex vivo cultures obtained from relapsed myeloma patients treated with LEN, showing a significant increase of DC differentiation from peripheral blood monocytes. In conclusion, LEN increased the expression of mature dendritic markers both directly and indirectly and enhanced DC ability to stimulate T cell proliferation and to release chemokines. This suggests a new possible mechanism by which LEN could exert its anti-myeloma activity., Competing Interests: CONFLICTS OF INTEREST N.G. received a research grant from Celgene Italy and Janssen Pharmaceutical.

Bone marrow monocytes are primarily committed to osteoclast formation. It is, however, unknown whether potential primary alterations are specifically present in bone marrow monocytes from patients with multiple myeloma, smoldering myeloma or monoclonal gammopathy of undetermined significance. We analyzed the immunophenotypic and transcriptional profiles of bone marrow CD14 + monocytes in a cohort of patients with different types of monoclonal gammopathies to identify alterations involved in myeloma-enhanced osteoclastogenesis. The number of bone marrow CD14 + CD16 + cells was higher in patients with active myeloma than in those with smoldering myeloma or monoclonal gammopathy of undetermined significance. Interestingly, sorted bone marrow CD14 + CD16 + cells from myeloma patients were more pro-osteoclastogenic than CD14 + CD16-cells in cultures ex vivo Moreover, transcriptional analysis demonstrated that bone marrow CD14 + cells from patients with multiple myeloma (but neither monoclonal gammopathy of undetermined significance nor smoldering myeloma) significantly upregulated genes involved in osteoclast formation, including IL21R IL21R mRNA over-expression by bone marrow CD14 + cells was independent of the presence of interleukin-21. Consistently, interleukin-21 production by T cells as well as levels of interleukin-21 in the bone marrow were not significantly different among monoclonal gammopathies. Thereafter, we showed that IL21R over-expression in CD14 + cells increased osteoclast formation. Consistently, interleukin-21 receptor signaling inhibition by Janex 1 suppressed osteoclast differentiation from bone marrow CD14 + cells of myeloma patients. Our results indicate that bone marrow monocytes from multiple myeloma patients show distinct features compared to those from patients with indolent monoclonal gammopathies, supporting the role of IL21R over-expression by bone marrow CD14 + cells in enhanced osteoclast formation., (Copyright© Ferrata Storti Foundation.)

The skin is a possible site of extramedullary localization in multiple myeloma (MM) patients; however, the mechanisms involved in this process are poorly understood. We describe the case of a refractory MM patient who developed a cutaneous localization under bortezomib treatment and we further expanded observations in other eight MM patients. We focused on the expression of genes involved in plasma cell skin homing, including CCR10, which was highly expressed. Moreover, we observed a lack of CXCR4 surface expression and the down-regulation of ICAM1/CD54 throughout the progression of the disease, suggesting a possible mechanism driving the escape of MM cells from the bone marrow into the skin.

Galectin-1 (Gal-1) is involved in tumoral angiogenesis, hypoxia and metastases. Actually the Gal-1 expression profile in multiple myeloma (MM) patients and its pathophysiological role in MM-induced angiogenesis and tumoral growth are unknown. In this study, we found that Gal-1 expression by MM cells was upregulated in hypoxic conditions and that stable knockdown of hypoxia inducible factor-1α significantly downregulated its expression. Therefore, we performed Gal-1 inhibition using lentivirus transfection of shRNA anti-Gal-1 in human myeloma cell lines (HMCLs), and showed that its suppression modified transcriptional profiles in both hypoxic and normoxic conditions. Interestingly, Gal-1 inhibition in MM cells downregulated proangiogenic genes, including MMP9 and CCL2, and upregulated the antiangiogenic ones SEMA3A and CXCL10. Consistently, Gal-1 suppression in MM cells significantly decreased their proangiogenic properties in vitro. This was confirmed in vivo, in two different mouse models injected with HMCLs transfected with anti-Gal-1 shRNA or the control vector. Gal-1 suppression in both models significantly reduced tumor burden and microvascular density as compared with the control mice. Moreover, Gal-1 suppression induced smaller lytic lesions on X-ray in the intratibial model. Overall, our data indicate that Gal-1 is a new potential therapeutic target in MM blocking angiogenesis.

The importance of glutamine (Gln) metabolism in multiple myeloma (MM) cells and its potential role as a therapeutic target are still unknown, although it has been reported that human myeloma cell lines (HMCLs) are highly sensitive to Gln depletion. In this study, we found that both HMCLs and primary bone marrow (BM) CD138(+) cells produced large amounts of ammonium in the presence of Gln. MM patients have lower BM plasma Gln with higher ammonium and glutamate than patients with indolent monoclonal gammopathies. Interestingly, HMCLs expressed glutaminase (GLS1) and were sensitive to its inhibition, whereas they exhibited negligible expression of glutamine synthetase (GS). High GLS1 and low GS expression were also observed in primary CD138(+) cells. Gln-free incubation or treatment with the glutaminolytic enzyme l-asparaginase depleted the cell contents of Gln, glutamate, and the anaplerotic substrate 2-oxoglutarate, inhibiting MM cell growth. Consistent with the dependence of MM cells on extracellular Gln, a gene expression profile analysis, on both proprietary and published datasets, showed an increased expression of the Gln transporters SNAT1, ASCT2, and LAT1 by CD138(+) cells across the progression of monoclonal gammopathies. Among these transporters, only ASCT2 inhibition in HMCLs caused a marked decrease in Gln uptake and a significant fall in cell growth. Consistently, stable ASCT2 downregulation by a lentiviral approach inhibited HMCL growth in vitro and in a murine model. In conclusion, MM cells strictly depend on extracellular Gln and show features of Gln addiction. Therefore, the inhibition of Gln uptake is a new attractive therapeutic strategy for MM., (© 2016 by The American Society of Hematology.)

Today the sepsis represents a very important clinical entity. The Surviving Sepsis Campaign assessed an incidence of sepsis equal to 3 cases/1,000 inhabitants. In UK more than 30,000 cases of severe sepsis are calculated; furthermore the patients with sepsis are increasing worldwide (near 18 millions of cases per year). Because of its high mortality, the sepsis represents one of the main causes of death in the world, also in the developing countries where it causes near sixty percent of the total deaths yearly. The early diagnosis and therapy are very important elements for the outcome of the patients. The Authors present the results of the adoption in their hospital of a guidelines document for the management of the septic patient, that show a decrease of their mortality due to the early diagnosis and specific treatments.

Myelodysplastic syndrome (MDS) risk correlates with advancing age, therapy-induced DNA damage, and/or shorter telomeres, but whether telomere erosion directly induces MDS is unknown. Here, we provide the genetic evidence that telomere dysfunction-induced DNA damage drives classical MDS phenotypes and alters common myeloid progenitor (CMP) differentiation by repressing the expression of mRNA splicing/processing genes, including SRSF2. RNA-seq analyses of telomere dysfunctional CMP identified aberrantly spliced transcripts linked to pathways relevant to MDS pathogenesis such as genome stability, DNA repair, chromatin remodeling, and histone modification, which are also enriched in mouse CMP haploinsufficient for SRSF2 and in CD34(+) CMML patient cells harboring SRSF2 mutation. Together, our studies establish an intimate link across telomere biology, aberrant RNA splicing, and myeloid progenitor differentiation., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Hypoxia-inducible transcription factor-1 (HIF-1α) is overexpressed in multiple myeloma (MM) cells within the hypoxic microenvironment. Herein, we explored the effect of persistent HIF-1α inhibition by a lentivirus short hairpin RNA pool on MM cell growth either in vitro or in vivo and on the transcriptional and pro-angiogenic profiles of MM cells. HIF-1α suppression did not have a significant impact on MM cell proliferation and survival in vitro although, increased the antiproliferative effect of lenalidomide. On the other hand, we found that HIF-1α inhibition in MM cells downregulates the pro-angiogenic genes VEGF, IL8, IL10, CCL2, CCL5 and MMP9. Pro-osteoclastogenic cytokines were also inhibited, such as IL-7 and CCL3/MIP-1α. The effect of HIF-1α inhibition was assessed in vivo in nonobese diabetic/severe combined immunodeficiency mice both in a subcutaneous and an intratibial MM model. HIF-1α inhibition caused a dramatic reduction in the weight and volume of the tumor burden in both mouse models. Moreover, a significant reduction of the number of vessels and vascular endothelial growth factors (VEGFs) immunostaining was observed. Finally, in the intratibial experiments, HIF-1α inhibition significantly blocked bone destruction. Overall, our data indicate that HIF-1α suppression in MM cells significantly blocks MM-induced angiogenesis and reduces MM tumor burden and bone destruction in vivo, supporting HIF-1α as a potential therapeutic target in MM.

Multiple myeloma (MM)-induced osteoclast (OC) formation is mainly due to an imbalance of the receptor activator NF-κB ligand (RANKL)-osteoprotegerin (OPG) ratio in favor of RANKL in the bone microenvironment and to the CCL3 production by MM cells. The purpose of the study was to investigate the effect of the immunomodulatory drugs on RANKL/OPG ratio, the production of pro-osteoclastogenic cytokines, and MM-induced OC formation. We found that in vivo concentrations of both lenalidomide (LEN) and pomalidomide (POM) significantly blunted RANKL upregulation normalizing the RANKL/OPG ratio in human osteoprogenitor cells (PreOBs) when co-cultured with MM cells and also inhibited CCL3 production by MM cells. A reduction in CD49d expression, a molecule critically involved in RANKL upregulation in the MM microenvironment, accompanied this effect. Consistently, the pro-osteoclastogenic property of MM cells co-cultured with PreOBs was reduced by both LEN and POM. We further investigated the effect of these drugs on the transcriptional profile of both MM cells and PreOBs by microarray analysis, which showed that adhesion molecules, such as ITGA8 and ICAM2, are significantly downregulated in MM cells. Our data suggest that LEN and POM inhibit MM-induced OC formation through normalization of the RANKL/OPG ratio targeting the expression of adhesion molecules by MM cells., (Copyright © 2013 ISEH - Society for Hematology and Stem Cells. Published by Elsevier Inc. All rights reserved.)

Multiple myeloma (MM) is characterized by the impaired osteogenic differentiation of human mesenchymal stromal cells (hMSCs). Canonical Wnt signaling is critical for the regulation of bone formation, however, recent evidence suggests that the non-canonical Wnt agonist Wnt5a stimulates human osteoblastogenesis through its co-receptor Ror2. The effects of MM cells on non-canonical Wnt signaling and the effect of the activation of this pathway on MM-induced osteoblast exhaustion are not known and were investigated in this study. We found that the osteogenic differentiation of bone marrow hMSCs toward osteoprogenitor cells (PreOB) significantly increased Ror2 expression, and that MM cells inhibit Ror2 expression by PreOB in co-culture by inhibiting the non-canonical Wnt5a signaling. The activation of the non-canonical Wnt pathway in hMSCs by means of Wnt5a treatment and the overexpression of Wnt5 or Ror2 by lentiviral vectors increased the osteogenic differentiation of hMSCs and blunted the inhibitory effect of MM in co-culture. Consistently, Wnt5a inhibition by specific small interfering RNA reduced the hMSC expression of osteogenic markers. Our findings demonstrate that the Wnt5a/Ror2 pathway is involved in the pathophysiology of MM-induced bone disease and that the activation of the non-canonical Wnt5a/Ror2 pathway in hMSCs increases osteogenic differentiation and may counterbalance the inhibitory effect of MM cells.

The involvement of osteocytes in multiple myeloma (MM)-induced osteoclast (OCL) formation and bone lesions is still unknown. Osteocytes regulate bone remodelling at least partially, as a result of their cell death triggering OCL recruitment. In this study, we found that the number of viable osteocytes was significantly smaller in MM patients than in healthy controls, and negatively correlated with the number of OCLs. Moreover, the MM patients with bone lesions had a significantly smaller number of viable osteocytes than those without, partly because of increased apoptosis. These findings were further confirmed by ultrastructural in vitro analyses of human preosteocyte cells cocultured with MM cells, which showed that MM cells increased preosteocyte death and apoptosis. A micro-array analysis showed that MM cells affect the transcriptional profiles of preosteocytes by upregulating the production of osteoclastogenic cytokines such as interleukin (IL)-11, and increasing their pro-osteoclastogenic properties. Finally, the osteocyte expression of IL-11 was higher in the MM patients with than in those without bone lesions. Our data suggest that MM patients are characterized by a reduced number of viable osteocytes related to the presence of bone lesions, and that this is involved in MM-induced OCL formation.

Homeobox (HOX) gene transcription factors are frequently deregulated in hematologic malignancies and involved in leukemogenic transformation [1]. Moreover, their overexpression has been associated with tumoral-induced neoangiogenesis in solid cancer [2]. The expression and the role of these genes have not yet been completely elucidated in multiple myeloma (MM). Recently, we reported that a small fraction of MM patients shows a HOXB7 overexpression as compared with normal samples and that HOXB7 expression correlates with bone marrow angiogenesis and the production of the proangiogenic factors by MM cells [3]. Other authors previously reported that HOXA cluster genes are expressed in a small fraction of MM patients [4]. Herein, we extended our previous evidences with the evaluation of the expression level of HOXB7 and the other gene family members in a large number of primary MM cells in relationship with the different molecular subgroups of MM and the presence of specific chromosome translocations. We found that HOXB7 and other genes of HOX family have a preferential distribution based on the characteristics of molecular MM subtypes based on the translocations/cyclins (TC) classification, suggesting a potential relationship between HOX genes expression, angiogenesis, and molecular features of MM patients.

The bone marrow microenvironment in multiple myeloma is characterized by an increased microvessel density. The production of pro-angiogenic molecules is increased and the production of angiogenic inhibitors is suppressed, leading to an "angiogenic switch". Here we present an overview of the role of angiogenesis in multiple myeloma, the pro-angiogenic factors produced by myeloma cells and the microenvironment, and the mechanisms involved in the myeloma-induced angiogenic switch. Current data suggest that the increased bone marrow angiogenesis in multiple myeloma is due to the aberrant expression of angiogenic factors by myeloma cells, the subsequent increase in pro-angiogenic activity of normal plasma cells as a result of myeloma cell angiogenic activity, and the increased number of plasma cells overall. Hypoxia also contributes to the angiogenic properties of the myeloma marrow microenvironment. The transcription factor hypoxia-inducible factor-1α is overexpressed by myeloma cells and affects their transcriptional and angiogenic profiles. In addition, potential roles of the tumor suppressor gene inhibitor of growth family member 4 and homeobox B7 have also been recently highlighted as repressors of angiogenesis and pro-angiogenic related genes, respectively. This complex pathogenetic model of myeloma-induced angiogenesis suggests that several pro-angiogenic molecules and related genes in myeloma cells and the microenvironment are potential therapeutic targets.

The deregulation of the homeobox genes as homeoboxB (HOXB)-7 has been previously associated to tumor progression and angiogenesis; here we investigated the potential role of HOXB7 in the pro-angiogenic properties of multiple myeloma (MM) cells. We found that HOXB7 was expressed in 10 out of 22 MM patients analyzed at the diagnosis related to high bone marrow angiogenesis and overexpressed in about 40% of myeloma cell lines compared with normal plasma cells. Enforced HOXB7 expression in MM cells by a lentiviral vector significantly modified their transcriptional and angiogenic profile, checked by combined microarray and angiogenesis PCR analyses, upregulating VEGFA, FGF2, MMP2, WNT5a and PDGFA and downregulating thrombospoindin-2. The pro- and anti-angiogenic HOXB7-related gene signature was also validated in a large independent dataset of MM patients. Accordingly, MM-induced vessel formation was significantly increased by HOXB7 overexpression both in vitro angiogenic and chorioallantoic membrane assays, as well as the HOXB7 silencing by small interfering RNA inhibited the production of angiogenic factors, and the pro-angiogenic properties of MM cells. Finally, in SCID-NOD mice we confirmed that HOXB7 overexpression by MM cells stimulated tumor growth, increased MM-associated angiogenesis and the expression of pro-angiogenic genes by microarray analysis supporting the critical role of HOXB7 in the angiogenic switch in MM.

Objective: Multiple myeloma (MM) cells are extremely resistant to drug-induced apoptosis due to both intrinsic- and bone marrow (BM) microenvironment-dependent drug resistance particularly supported by bone cells. Growing evidence suggest that the osteoclast inhibitor zoledronic acid (ZOL) exerts both indirect and direct anti-tumoral effects, including an in vitro proapoptotic effect on MM cells, although this property has not yet been clearly observed in MM patients., Materials and Methods: In this study, we attempt to better define the cytotoxic effect of ZOL on MM cells in order to identify novel drug combinations able to potentiate its proapoptotic effect., Results: Our data shows that ZOL at concentrations ranging from 10 to 100 μM was able to induce MM cell apoptosis overcoming the prosurvival effect of both stromal cells and osteoclasts and independent of the intrinsic bortezomib resistance of MM cells. Interestingly, we found that the capacity of ZOL to induce apoptosis in bortezomib-resistant cells was associated with a downregulation of the proapoptotic molecule myeloid cell leukemia-1. A transcriptional analysis by microarray was also performed to identify genes specifically modulated by ZOL in bortezomib-resistant MM cells. Finally, we show an additive effect of arsenic trioxide on apoptosis when used in combination with ZOL., Conclusions: Our in vitro data suggest that the use of ZOL at appropriate doses could be explored clinically in bortezomib-resistant MM patients and combined with arsenic trioxide to increase its proapoptotic effect., (Copyright © 2011 ISEH - Society for Hematology and Stem Cells. Published by Elsevier Inc. All rights reserved.)

Purpose: Multiple myeloma (MM) derives from plasmablast/plasma cells that accumulate in the bone marrow. Different microenvironmental factors may promote metastatic dissemination especially to the skeleton, causing bone destruction. The balance between osteoclast and osteoblast activity represents a critical issue in bone remodeling. Thus, we investigated whether interluekin-27 (IL-27) may function as an antitumor agent by acting directly on MM cells and/or on osteoclasts/osteoblasts., Experimental Design: The IL-27 direct antitumor activity on MM cells was investigated in terms of angiogenesis, proliferation, apoptosis, and chemotaxis. The IL-27 activity on osteoclast/osteoblast differentiation and function was also tested. In vivo studies were done using severe combined immunodeficient/nonobese diabetic mice injected with MM cell lines. Tumors from IL-27- and PBS-treated mice were analyzed by immunohistochemistry and PCR array., Results: We showed that IL-27 (a) strongly inhibited tumor growth of primary MM cells and MM cell lines through inhibition of angiogenesis, (b) inhibited osteoclast differentiation and activity and induced osteoblast proliferation, and (c) damped in vivo tumorigenicity of human MM cell lines through inhibition of angiogenesis., Conclusions: These findings show that IL-27 may represent a novel therapeutic agent capable of inhibiting directly MM cell growth as well as osteoclast differentiation and activity.

Objective: Multiple myeloma (MM) is characterized by a high incidence of osteolytic bone lesions, which have been previously correlated with the gene expression profiles of MM cells. The aim of this study was to investigate the transcriptional patterns of cells in the bone microenvironment and their relationships with the presence of osteolysis in MM patients., Materials and Methods: Both mesenchymal (MSC) and osteoblastic (OB) cells were isolated directly from bone biopsies of MM patients and controls to perform gene expression profiling by microarrays and real-time polymerase chain reaction on selected bone-related genes., Results: We identified a series of upregulated and downregulated genes that were differentially expressed in the MSC cells of osteolytic and nonosteolytic patients. Comparison of the osteolytic and nonosteolytic samples also showed that the MSC cells and OB had distinct transcriptional patterns. No significantly modulated genes were found in the OBs of the osteolytic and nonosteolytic patients., Conclusions: Our data suggest that the gene expression profiles of cells of the bone microenvironment are different in MM patients and controls, and that MSC cells, but not OBs, have a distinct transcriptional pattern associated with the occurrence of bone lesions in MM patients. These data support the idea that alterations in MSC cells may be involved in MM bone disease., (Copyright 2010 ISEH - Society for Hematology and Stem Cells. Published by Elsevier Inc. All rights reserved.)

The expression of the chemokine CC-chemokine ligand 20 (CCL20)/macrophage inflammatory protein (MIP)-3alpha and its receptor CC-chemokine receptor 6 (CCR6) by multiple myeloma (MM) and microenvironment cells and their potential relationship with osteoclast (OC) formation and osteolytic bone lesions in MM patients was investigated in this study. First, we found that MM cells rarely produce CCL20/MIP-3alpha but up-regulate its production by bone marrow (BM) osteoprogenitor cells and osteoblasts in coculture with the involvement of soluble factors as interleukin-1beta and tumor necrosis factor alpha. MM cells also stimulate both CCL20/MIP-3alpha and CCR6 expression by OCs in coculture. Thereafter, we showed that CCL20/MIP-3alpha significantly increases both the number of multinucleated tartrate-resistant acid phosphatase-positive OCs and receptor activator of nuclear factor-kappaB-positive OC progenitor cells similar to CCL3/MIP-1alpha. Finally, we found that blocking anti-CCL20/MIP-3alpha and anti-CCR6 antibodies significantly inhibits MM-induced OC formation. In vitro data were further expanded in vivo analyzing a total number of 64 MM patients. Significantly higher CCL20/MIP-3alpha levels were detected in MM patients versus monoclonal gammopathy of uncertain significance (MGUS) subjects and in MM osteolytic patients versus nonosteolytic ones. Moreover, a significant increase of CCL20/MIP-3alpha-positive osteoblasts in osteolytic MM patients compared with nonosteolytic ones was observed. Interestingly, no significant difference in BM CCL20/MIP-3alpha expression and level was observed between MGUS and nonosteolytic MM patients. Our data indicate that CCL20/MIP-3alpha and its receptor CCR6 are up-regulated in the bone microenvironment by MM cells and contribute to OC formation and osteolytic bone lesions in MM patients.