Multiple myeloma increases nerve growth factor and other pain-related markers through interactions with the bone microenvironment

Obesity as a risk factor for multiple myeloma: insight on the role of adipokines

Multiple myeloma (MM) is a hematologic disorder characterized by the accumulation of malignant plasma cells in the bone marrow. Genetic and environmental factors are contributed to the etiology of MM. Notably, studies have shown that obesity increases the risk of MM and worsens outcomes for MM patients. Adipokines play an important role in mediating the close association between MM and metabolic derangements. In this review, we summarize the epidemiologic studies to show that the risk of MM is increased in obese. Accumulating clinical evidence suggests that adipokines could display a correlation with MM. In vitro and in vivo studies have shown that adipokines are linked to MM, including roles in the biological behavior of MM cells, cancer-associated bone loss, the progression of MM, and drug resistance. Current and potential therapeutic strategies targeted to adipokines are discussed, proposing that adipokines can guide early patient diagnosis and treatment.

Metastatic Infiltration of Nervous Tissue and Periosteal Nerve Sprouting in Multiple Myeloma-Induced Bone Pain in Mice and Human

Multiple myeloma (MM) is a neoplasia of B plasma cells that often induces bone pain. However, the mechanisms underlying myeloma-induced bone pain (MIBP) are mostly unknown. Using a syngeneic MM mouse model, we show that periosteal nerve sprouting of calcitonin gene-related peptide (CGRP+) and growth associated protein 43 (GAP43+) fibers occurs concurrent to the onset of nociception and its blockade provides transient pain relief. MM patient samples also showed increased periosteal innervation. Mechanistically, we investigated MM induced gene expression changes in the dorsal root ganglia (DRG) innervating the MM-bearing bone of male mice and found alterations in pathways associated with cell cycle, immune response and neuronal signaling. The MM transcriptional signature was consistent with metastatic MM infiltration to the DRG, a never-before described feature of the disease that we further demonstrated histologically. In the DRG, MM cells caused loss of vascularization and neuronal injury, which may contribute to late-stage MIBP. Interestingly, the transcriptional signature of a MM patient was consistent with MM cell infiltration to the DRG. Overall, our results suggest that MM induces a plethora of peripheral nervous system alterations that may contribute to the failure of current analgesics and suggest neuroprotective drugs as appropriate strategies to treat early onset MIBP.SIGNIFICANCE STATEMENT Multiple myeloma (MM) is a painful bone marrow cancer that significantly impairs the quality of life of the patients. Analgesic therapies for myeloma-induced bone pain (MIBP) are limited and often ineffective, and the mechanisms of MIBP remain unknown. In this manuscript, we describe cancer-induced periosteal nerve sprouting in a mouse model of MIBP, where we also encounter metastasis to the dorsal root ganglia (DRG), a never-before described feature of the disease. Concomitant to myeloma infiltration, the lumbar DRGs presented blood vessel damage and transcriptional alterations, which may mediate MIBP. Explorative studies on human tissue support our preclinical findings. Understanding the mechanisms of MIBP is crucial to develop targeted analgesic with better efficacy and fewer side effects for this patient population.

Obesity and myeloma: Clinical and mechanistic contributions to disease progression

Obesity and obesogenic behaviors are positively associated with both monoclonal gammopathy of unknown significance (MGUS) and multiple myeloma (MM). As the only known modifiable risk factor, this association has emerged as a new potential target for MM prevention, but little is known about the mechanistic relationship of body weight with MM progression. Here we summarize epidemiological correlations between weight, body composition, and the various stages of myeloma disease progression and treatments, as well as the current understanding of the molecular contributions of obesity-induced changes in myeloma cell phenotype and signaling. Finally, we outline groundwork for the future characterization of the relationship between body weight patterns, the bone marrow microenvironment, and MM pathogenesis in animal models, which have the potential to impact our understanding of disease pathogenesis and inform MM prevention messages.

Brain-derived neurotrophic factor: focus on the pathogenesis of multiple myeloma and the development of treatment-induced peripheral neuropathy

For many years, intensive research has been carried out on the in-depth understanding of the pathogenesis of multiple myeloma (MM). Nevertheless, the multifactorial nature of the disease, the development of drug resistance, and the side effects of therapy, make it difficult to effectively treat patients. One of the many factors involved in the pathogenesis of MM is brain-derived neurotrophic factor (BDNF). This factor is widely described as a neuroregenerative and neuroprotective agent, but it also regulates non-neuronal cell functions, such as proliferation, apoptosis, and viability. Therefore, BDNF appears to be a good therapeutic target in MM. On the other hand, its decreased concentration during treatment closely correlates with the development of peripheral neuropathy (PN). BDNF dualism requires a detailed understanding of its action on individual molecular mechanisms. Perhaps the optimization of the BDNF level will contribute to the improvement of MM treatment and the reduction of chemotherapy side effects.

Transplantation of autologous bone marrow pre-loaded ex vivo with oncolytic myxoma virus is efficacious against drug-resistant Vk*MYC mouse myeloma

Multiple myeloma (MM) is a hematological malignancy of plasma cells that remains incurable despite significant progress with myeloablative regimens and autologous stem cell transplantation for eligible patients and, more recently with T cell redirected immunotherapy. Recently, we reported that ex vivo virotherapy with oncolytic myxoma virus (MYXV) improved MM-free survival in an autologous-transplant Balb/c mouse model. Here, we tested the Vk*MYC transplantable C57BL/6 mouse MM model that more closely recapitulates human disease. In vitro, the murine bortezomib-resistant Vk12598 cell line is fully susceptible to MYXV infection. In vivo results demonstrate: (i) autologous bone marrow (BM) leukocytes armed ex vivo with MYXV exhibit moderate therapeutic effects against MM cells pre-seeded into recipient mice; (ii) Cyclophosphamide in combination with BM/MYXV delays the onset of myeloma in mice seeded with Vk12598 cells; (iii) BM/MYXV synergizes with the Smac-mimetics LCL161 and with immune checkpoint inhibitor α-PD-1 to control the progression of established MM in vivo, resulting in significant improvement of survival rates and decreased of tumor burden; (iv) Survivor mice from (ii) and (iii), when re-challenged with fresh Vk12598 cells, developed acquired anti-MM immunity. These results highlight the utility of autologous BM grafts armed ex vivo with oncolytic MYXV alone or in combination with chemotherapy/immunotherapy to treat drug-resistant MM in vivo.

Myeloma and marrow adiposity: Unanswered questions and future directions

Multiple myeloma (MM) is a haematological malignancy characterised by the proliferation and accumulation of terminally differentiated abnormal plasma cells in the bone marrow. Patients suffer from bone pain, factures, anaemia, osteolytic lesions and renal failure. Despite recent advancement in therapy MM remains an incurable disease due to the emergences of drug resistance and frequent relapse. For many decades, research has been heavily focused on understanding the relationship between bone cells such as osteoblast, osteocytes and osteoclasts and the infiltrating tumour cells. However, it is now clear that the tumour-supportive bone microenvironment including cellular and non-cellular components play an important role in driving MM progression and bone disease. One of the most abundant cell types in the bone microenvironment is the bone marrow adipocyte (BMAd). Once thought of as inert space filling cells, they have now been recognised as having specialised functions, signalling in an autocrine, paracrine and endocrine manner to support normal systemic homeostasis. BMAds are both an energy store and a source of secreted adipokines and bioactive substances, MM cells are able to hijack this metabolic machinery to fuel migration, growth and survival. With global obesity on the rise, it has never been more important to further understand the contribution these cells have in both normal and disease settings. The aim of this review is to summarise the large body of emerging evidence supporting the interplay between BMAds and MM cells and to delineate how they fit into the vicious cycle of disease.

Multiple myeloma-A painful disease of the bone marrow

Multiple myeloma is a bone marrow neoplasia with an incidence of 6/100,000/year in Europe. While the disease remains incurable, the development of novel treatments such as autologous stem cell transplantation, proteasome inhibitors and monoclonal antibodies has led to an increasing subset of patients living with long-term myeloma. However, more than two thirds of patients suffer from bone pain, often described as severe, and knowledge on the pain mechanisms and its effect on their health-related quality of life (HRQoL) is limited. In this review, we discuss the mechanisms of myeloma bone disease, the currently available anti-myeloma treatments and the lessons learnt from clinical studies regarding HRQoL in myeloma patients. Moreover, we discuss the mechanisms of cancer-induced bone pain and the knowledge that animal models of myeloma-induced bone pain can provide to identify novel analgesic targets. To date, information regarding bone pain and HRQoL in myeloma patients is still scarce and an effort should be made to use standardised questionnaires to assess patient-reported outcomes that allow inter-study comparisons of the available clinical data.

JZL184, A Monoacylglycerol Lipase Inhibitor, Induces Bone Loss in a Multiple Myeloma Model of Immunocompetent Mice

Multiple myeloma (MM) patients develop osteolysis characterised by excessive osteoclastic bone destruction and lack of osteoblast bone formation. Pharmacological manipulation of monoacylglycerol lipase (MAGL), an enzyme responsible for the degradation of the endocannabinoid 2-arachidonoyl glycerol (2-AG), reduced skeletal tumour burden and osteolysis associated with osteosarcoma and advanced breast and prostate cancers. MM and hematopoietic, immune and bone marrow cells express high levels of type 2 cannabinoid receptor and osteoblasts secrete 2-AG. However, the effects of MAGL manipulation on MM have not been investigated. Here, we report that treatment of pre-osteoclasts with non-cytotoxic concentrations of JZL184, a verified MAGL inhibitor, enhanced MM- and RANKL-induced osteoclast formation and size in vitro. Exposure of osteoblasts to JZL184 in the presence of MM cell-derived factors reduced osteoblast growth but had no effect on the ability of these cells to mature or form bone nodules. In vivo, administration of JZL184 induced a modest, yet significant, bone loss at both trabecular and cortical compartments of long bones of immunocompetent mice inoculated with the syngeneic 5TGM1-GFP MM cells. Notably, JZL184 failed to inhibit the in vitro growth of a panel of mouse and human MM cell lines, or reduce tumour burden in mice. Thus, MAGL inhibitors such as JZL184 can exacerbate MM-induced bone loss.

Nerve growth factor promotes ASIC1a expression via the NF-κB pathway and enhances acid-induced chondrocyte apoptosis

Nerve growth factor (NGF) is a neurotrophic factor that is thought to have a broad role in the nervous system and tumors, and has recently been described as a mediator of inflammation. It is not clear whether or not NGF participates in apoptosis of articular chondrocytes. In this study, we determined if NGF affects ASIC1a expression and NF-κB P65 activation in rat chondrocytes, and measured the effectiveness of NGF on apoptotic protein expression in acid-induced chondrocytes. NGF was shown to up-regulate the level of ASIC1a in a dose- and time-dependent fashion. Simultaneously, NGF activated NF-κB P65 in chondrocytes. Additionally, the elevated ASIC1a expression induced by NGF was eliminated by the NF-κB inhibitor (PDTC) in chondrocytes. Moreover, NGF reduced cell viability and induced LDH release under the premise of acid-induced articular chondrocytes. Furthermore, NGF could enhance cleaved-caspase 9 and cleaved-PARP expression in acid-pretreated chondrocytes, and which could be inhibited by using psalmotoxin 1(PcTX1) or PDTC. Together, these results indicated that NGF may up-regulate ASIC1a expression through the NF-κB signaling pathway, and further promote acid-induced apoptosis of chondrocytes.