1. Introduction
Multiple myeloma (MM) is a hematological malignancy characterized by the accumulation of pathological monoclonal plasma cells, predominantly in the bone marrow [ 1 ]. Despite some advanced treatment options, the disease remains incurable with a 5-year relative survival of 57.9% (SEER 17 2012–2018) [ 2 ]. Current research into the underlying biology of MM has shed some light on the role of extracellular vesicles (EVs) in the pathogenesis and evolution of this condition [ 3 ]. MM evolves from the monoclonal gammopathy of undetermined significance (MGUS), in most cases via the acquisition of genomic mutations [ 4 , 5 ]. MGUS is defined by a serum non-IgM-type monoclonal protein of <3 g/dL (typically non-IgM-type), <10% clonal BM plasma cells, and the absence of end-organ damage [ 6 ]. MGUS may evolve to an intermediate stage—smoldering multiple myeloma (SMM), which is also asymptomatic, but with a higher risk of progression to malignant disease in the first 5 years than MGUS [ 7 ].
Extracellular vesicles are a heterogeneous group of particles that is steadily gaining acknowledgment in the medical field, as a vital part of the intercellular communication [ 8 ]. Not only do they mediate communication between healthy cells but are also an important part of pathological conditions, among which cancer is the most thoroughly studied [ 9 ]. Apart from malignancy, EVs’ functions are being investigated in many fields of medical research. Neurology is embracing EVs as a novel drug delivery system [ 10 ], a promising diagnostic tool distinguishing progressive supranuclear palsy and Parkinson’s disease [ 11 ], immunomodulators that may prevent inflammation-induced neural degeneration in ischemic patients [ 12 ], just to name a few. Cardiovascular research is focused on using EVs as a future acellular therapy for myocardial repair [ 13 ] and biomarkers of diverse clinical settings [ 14 ]. Studies on lung diseases have shown the possible application of circulating EVs as an exacerbation indicator in chronic obstructive pulmonary disease [ 15 ].
The classification and the nomenclature of EVs is an ongoing problem. The most commonly used classification is based on their biogenesis. Therefore, three groups are distinguished: exosomes are the EVs created by a fusion of multivesicular bodies (MVB) with the plasma membrane (PM); microvesicles (MVs) are established by direct budding from the PM; and apoptotic extracellular vesicles (ApoEVs) are the result of apoptosis ( Table 1 ). This approach is not recommended by the International Society for Extracellular Vesicles (ISEV) since the consensus on the specific markers for each group is still to be reached [ 16 ]. Instead, general terms describing EVs’ physical characteristics, biochemical components, depiction of the condition, and/or the cell of origin, is recommended [ 16 ]. For instance, the classification, based on the size of EVs, which differentiates two classes: small EVs (diameter < 200 nm) and large EVs (diameter > 200 nm), is advocated [ 16 ].
As multiple studies fail to meet the criteria of inclusion in traditionally distinguished EV subgroups, to avoid any confusion, this article will apply the general term “extracellular vesicles” instead of using different subtype names, as proposed by the ISEV. In this review, the current state of knowledge on the role of EVs in the pathogenesis and progression of MM is presented.
2. Stages of MM Progression
Some genetic abnormalities (such as the acquisition of the hyperdiploidy, and the translocations involving the immunoglobulin heavy chain gene locus) are the trigger for the induction of plasma cell malignancy and can be detected in the MGUS and the SMM, years before proper MM development [ 1 ]. It seems that the main genetic mutations in the progression of myeloma take place in the early stage of the disease between MGUS and SMM, while the meaning of mutations between SMM and MM is more elusive. There exist two models of progression from SMM to MM. The first one, called “static progression”, is characterized by the same subclonal architecture of MM and SMM, suggesting that some factors other than genetic factors could play a role in the passage between these two stages. The second model, “spontaneous evolution”, depends on the random acquisition of new mutations, which also leaves space for further investigation [ 23 ]. It is proposed that the communication between the MM and the microenvironment of the bone marrow (BM), notably by EVs, is an important factor in the MM evolution [ 3 ]. Cell proliferation and tumor growth, angiogenesis, matrix remodeling and metastasis, immunosuppression, and drug resistance are some of the processes mediated by EVs and this article is an elaboration on them. It is known that a single EV can exert influence in multiple pathways of MM progression. However, simplification will be used for the sake of the clear structure of this review.
2.1. Tumor Growth and Proliferation
The microenvironment surrounding a tumor plays a vital role in its progression. As the tumor advances, it develops a network of connections between various BM populations to induce the proliferation of its cells, assuring its growth. Especially, the cross-talk with bone marrow mesenchymal stromal cells (BM-MSCs) is of great importance in this process [ 24 ] ( Figure 1 ).
Tumor-growth-inducing effects of EVs, deriving from multiple myeloma mesenchymal stromal cells (MM-MSC), are mediated by their modified cargo. The amended content of the EVs includes increased pro-proliferative protein levels (namely IL-6, CCL2, junction plakoglobin, and fibronectin) and an altered nucleic acid load [ 24 ] ( Figure 1 ). Decreased levels of microRNA (miR)-15a and augmented levels of long-non-coding RNAs (lncRNAs)—LINC00461 were found in proliferation-inducing MSC-derived EVs [ 24 , 25 ]. miR-15a, as well as miR-16, acts as a regulator of the BCL-2 expression that is a well-known apoptosis suppressor [ 26 ], whereas LINC00461 has a down-regulating ability on miR-15a and miR-16 by direct binding [ 25 ]. Therefore, it appears that the mechanism of the direct binding of miR-15a and miR-16 by LINC00461, might be the cause of decreased miR-15a levels found in the Roccaro et al.’s study and consequently, the increase of proliferation of malignant cells.
What is more, MSCs possess the ability to transform into cancer-associated fibroblasts (CAFs), in a process mediated by MM-derived EVs [ 27 , 28 ] ( Figure 1 ). These EVs had an augmented content of miR-21 and miR-146a, which promotes the proliferation and transformation of MSCs into CAFs, by inducing the expression of IL-6, stromal-derived factor 1 (SDF-1), fibroblast-activated protein (FAP), and α-smooth muscle actin (α-SMA) genes [ 27 ] ( Figure 1 ). Moreover, miR-146a transferred from the MM cells to MSCs increases the expression of the CXC ligand 1 (CXCL1), interferon-γ–inducible protein 10 (IP-10), and the CC chemokine ligand 5 (CCL5) in MSC [ 28 ] ( Figure 1 ). This process is mediated by the Notch pathway and its inhibition leads to the down-regulated cytokines production, therefore decreasing the MM cell growth [ 27 ].
As aforementioned, miR15a and miR-16 are MM suppressing factors, but interestingly other miRNAs, notably miR-10a, deriving from bone marrow stromal cells (BMSCs) and released in EVs, works in an opposite manner, encouraging the MM cell proliferation and tumor growth [ 29 ]. Probable gene targets in the MM cells include β-transducin repeat-containing E3 ubiquitin protein ligase (β-TRC), whose expression was augmented by the miR-10a overexpression [ 29 ] ( Figure 1 ). β-TRC is a part of the Skp1, cullin, F-box proteins (SCF) E3 ligase complex, which mediates the degradation of the Rap1 GTPase-activating protein 1 (Rap1GAP) required to induce the cell proliferation [ 30 ]. In line with this mechanism, the inhibition of β-TRC suppressed a pro-proliferative effect of miR-10a [ 29 ]. What is more, the bioinformatic analyses predicted ephrin receptor A8 kinase (EphA8) as a possible target gene for miR-10a, creating a novel potential miR-10a-EphA8-SEMA5A pathway [ 31 ]. Nevertheless, extensive research, including laboratory experiments, is yet to be performed to assess the value of this prediction. Interestingly, miR-10a induces apoptosis in BMSCs when the EV formation is blocked. Thus, the inhibition of the EV release might be a novel treatment for MM [ 29 ].
Stem cell-derived EVs increase the MAPK activation within the MM cells, nevertheless, the proliferation induction is dependent on the cellular origin of the cell [ 32 ]. Within 24 h, the decrease in the activation of MAPK was seen in the normal donor-deriving EV group, whereas myeloma EVs initiated the continuous MAPK activation, which translated into an augmented viability, proliferation, and translation initiation [ 32 ] ( Figure 1 ). Interestingly, similar findings regarding the antiproliferative effect of EVs deriving from normal donors cells, were found elsewhere [ 24 ]. Hence, a thorough analysis of EVs’ content across the BM populations could be beneficial to identify possible common antiproliferative pathways which might be used as new therapeutic targets.
All things considered, communication between MM and diverse cellular compartments of BM is of great importance, considering the induction of the proliferation and tumor growth. Nevertheless, MM cells may also induce this process in an auto-stimulatory way via the internalization of the CD147-positive EVs [ 33 ] ( Figure 1 ). EVs derived from human MM cell lines of the decreased CD147 expression, have been shown to induce the proliferation of MM cells in a weakened way [ 33 ]. The research investigating the EVs’ ability to serve as a carrier in the auto-stimulation processes of malignant cells may be a novel and important point of view, regarding EVs’ place in the tumor biology.
2.2. Progression
One of the main characteristics of cancer that greatly complicates the course of the disease is its ability to disseminate. To achieve its progression, MM requires the cooperation of its cells with the bone marrow of different skeletal sites [ 34 ]. Needless to say, efficient communication between these two must be established. There exists a number of studies that demonstrate the interaction between BM-MSCs and MM cells, which in turn, results in the tumor cell migration, proliferation, creation of a convenient microenvironment (for instance, through angiogenesis or osteoclastogenesis), and finally metastasis [ 35 , 36 , 37 ]. Recent findings identify EVs as an important means of communication between these two [ 24 , 32 ].
Throughout the disease, MM cells manage to influence the BM-MSCs, so that they start cooperating with them in order to enable metastasis [ 32 ]. It is not a peculiar characteristic of multiple myeloma, as it has been also shown in research, concerning other cancers [ 2 , 38 , 39 , 40 ].
The MM-EVs influence the BM-MSCs, and through this, the preconditioning of macrometastasis is possible. MM-EVs have been shown to influence BM-MSCs through the signal transducer and activator of transcription 3 (STAT3) and c-Jun N-terminal kinase (JNK) phosphorylation, in order to increase their survival [ 41 ]. As a result of the preconditioning, BM-MSCs can produce altered EVs (MM MSC-EVs) [ 41 ].
One of the components of great importance in the MM progression, are miRNAs derived from MM-EVs. miR-146 and miR-21, originating from MM-EVs, affect the cytokine production in BM-MSCs and favor their differentiation into CAFs. This is achieved through the activation of the cytokines cascade, in which molecules, such as IL-6, IL-8, CXCL1, and CCL5, to name a few, are secreted [ 42 , 43 ]. As a result, they positively affect the growth and migration of tumor cells. Moreover, the BM-MSCs secrete EVs containing miR-10a, which is subsequently incorporated by the MM cells, promote their proliferation and help create a suitable microenvironment for the MM cells to survive and, as already has been described above [ 29 ].
Not only cargo of the MM-EVs, but also their surface molecules, have been shown to exert a strong influence on the BM of MM patients. CD138 (also known as Syndecan-1) is a cell surface proteoglycan containing heparan sulfate, whose presence on the peripheral EVs was found to be correlated with the presence of bone lesions in MM patients [ 44 ]. The suggested mechanism which could explain this pathway is linked to the role of fibronectin. This molecule is bound to CD138 and exerts an influence on the MM cells via the p38 and pERK pathways, which in turn, leads to the expression of Dickkopf-related protein 1 (DKK1) and metalloproteinase-9 (MMP-9), two molecules with a favorable effect on the MM progression [ 45 ].
In MM patients, the extracellular circulating 20S proteasomes are also detected and their source is elusive. However, EVs are a highly probable source of them, as seen in the study focusing on T lymphocytes microvesicles [ 46 ]. The proteasome system’s function is the degradation of proteins involved in cellular processes, such as apoptosis, transcription, antigen processing, and hence, in the proliferation of cells, both normal and malignant [ 47 ]. The importance of 20S proteasomes in MM is highlighted by the fact that the circulating proteasome level is significantly elevated in active, versus smoldering MM, suggesting its role in the MM progression [ 48 ].
2.3. Angiogenesis
It has been shown in various studies that EVs also play a key role in the induction of angiogenesis [ 41 ], one of the ways in which cancer gains its abilities for further survival [ 49 ].
A study analyzing the naive MM-EVs and EVs pretreated with bortezomib (Bi-EVs), has shown that MM-EVs contain pro-angiogenic factors and internalized by EC, enhance the migration and proliferation of the latter. Bortezomib altered the levels of the pro-angiogenic and inflammatory proteins in MM-EVs. The expression of VEGF-R2 and several growth factors (such as VEGFA, platelet-derived growth factor-BB (PDGF-BB), angiogenin, and urokinase plasminogen activator receptor (uPAR)) were significantly reduced on Bi-EVs, compared to naive MM-EVs. The exposure of endothelial cells to naive MM-EVs and Bi-EVs was analyzed and apparently, exposure to naive EVs induced a trend of an increase in endothelial cell (EC) proliferation and migration, influencing the MAPK cascade mechanism, whereas Bi-EVs inhibited the EC proliferation and migration. The study demonstrated the cross-talk of EVs and EC, which results in angiogenesis in the progression of MM [ 50 ] ( Figure 2 ).
The formation of new vessels is known to be promoted by hypoxia, which is normally induced by the aggressive proliferation of MM cells in BM [ 51 , 52 ]. Under these conditions, various substances are secreted by the cancer cells to facilitate the formation of new vessels in an otherwise hostile environment [ 51 ]. The hypoxia-resistant MM cells (HR-MM cells) produce more EVs than their parental cells. The RNA components of these EVs seem to be of great importance as they differ significantly from those of the EVs of the parental cells. Some microRNA (notably miR-135b) of the HR-MM EVs play a role in blocking factor-inhibiting hypoxia-inducible factor 1 (FIH-1) in endothelial cells, which in turn promotes the endothelial tube formation [ 47 ]. Similarly, piRNA is an important regulator in the evolution of MM. piRNA-823 plays a significant role in angiogenesis, inducing the tumor growth and proliferation [ 53 ]. piRNA-823 increases in vitro the level of VEGF and IL-6, as well as restricts the apoptosis of the infected endothelial cells through the inhibition of the caspase-3 activation, downregulation of the BAX expression, and the production of ROS and NO [ 53 ] ( Figure 2 ).
RNAs are not only EV-derived inductors of angiogenesis. Several cytokines and other proteins known to be involved in the formation of vessels, such as the vascular endothelial growth factor-1 (VEGF), angiogenin, and CD147, to name a few, were detected as a cargo of EVs [ 39 , 54 , 55 ]. Worth mentioning is the effect of CD138 on the endothelial cells whose gene expression correlated with the increased density of microvessels in the BM in patients with MM and MGUS [ 56 ] ( Figure 2 ). It is yet to be researched if CD138 influences angiogenesis at the premetastatic niche.
Several studies found that not only MM-EVs can contribute to angiogenesis in the evolution of MM. Endothelial cells also generate EVs, which influence tumor invasion and angiogenesis. They release EVs containing metalloproteinases (MMPs) that lead to proteolysis, necessary for metastasis and free angiogenesis [ 57 ]. miR-126 is present in EC-derived EVs and exerts pro-angiogenic actions on the microenvironment and other ECs [ 58 ] ( Figure 2 ). Moreover, miR-126 contributes to establishing a pro-angiogenic microenvironment and promotes the hindlimb ischemia repair [ 59 ]. It is thought to act through the VEGF/PI3K/Akt pathway [ 60 ].
2.4. Matrix Remodeling and Osteolysis Induction
The formation of a suitable niche and dissemination are necessary steps in the neoplasm progression [ 61 ]. One of the roles of EVs in the MM evolution appears to be matrix remodeling and specifically, the induction of osteolysis, which in turn, facilitates the dissemination of MM and creates non-hostile conditions for the tumor to progress ( Figure 3 ). The BM provides a highly convenient niche for multiple myeloma and facilitates the further dissemination of the MM cells [ 24 ]. Therefore, it is not surprising that MM cells tend to diffuse to distant skeletal sites [ 62 ]. This affinity to the bone marrow results in what we call multiple myeloma-associated bone disease (MBD), which significantly reduces the quality of life of patients and increases morbidity [ 63 ].
A key function of EVs is the induction of bone resorption, whose role varies greatly from “freeing up” the space for the MM cells to reside to secreting factors influencing the tumor proliferation, such as TGF-β [ 64 ]. Physiologically, there exists a balance between the osteoclasts (OCs) and osteoblasts (OBs). Nevertheless, during the MM evolution, this balance is disturbed by the advantage of OCs which leads to osteolysis [ 44 ]. The multiple components of EVs take part in different pathways, in order to establish a suitable niche for the MM cells to disseminate. A study demonstrating the effects of MM EVs on the imbalance between OCs and OBs and hence, osteolysis has been conducted on the 5TGM1 MM murine model. The 5TGM1 EVs were shown to enhance the OCs activity as well as block the OBs differentiation and impede their functions, as a result of the transfer of DKK-1, the Wnt signaling inhibitor, which in turn, induced the reduction of the Runt-related transcription factor 2 (Runx2), osterix and collagen1A1 in OBs [ 65 ].
Another cause of the disturbed balance between OCs and OBs is a protein component of MM-EVs playing a role in osteoclastogenesis-amphiregulin (AREG), which is a ligand of the epithelial growth factor receptor (EGFR) [ 66 ]. AREG presents a vast range of functions. It activates EGFR in the osteoclast precursors, leading to their differentiation into mature OCs. It also promotes the secretion of osteoclastogenic cytokines, such as IL-8 from BM-MSCs. Finally, AREG blocks the mesenchymal stem cell differentiation into the OBs [ 67 ]. The study also shows another pathway in which the MM-EVs promote osteolysis: they have the ability to increase the secretion of RANKL and decrease the release of osteoprotegerin. The MM-EVs play an important role in inducing osteolysis, as they contribute greatly to the migration of the osteoclasts’ precursors and their survival. This is achieved by increasing the CXCR4 (CXC chemokine receptor type 4) and by upregulating the expression of Bcl-2 and AKT phosphorylation. What is more, MM-EVs promote bone resorption by augmenting the expression of important osteoclastogenic enzymes (TRAP, CTSK, MMP9) and inhibit the apoptosis of the osteoclast precursors by blocking the caspase-3 activity [ 68 ].
The RNA content of MM-EVs has a vital role in osteolysis in MM [ 69 ]. According to recent studies, MM-EVs contain miR-135b, which by being incorporated by BM-MSCs, targets and downregulates SMAD5 [ 47 ]. SMAD5 is a protein that, together with bone morphogenetic proteins (BMPs), govern the process of osteogenesis [ 47 ]. Its downregulation disturbs osteogenesis [ 47 ]. Another microRNA, miR-21, produced through the STAT3 pathway and stored in MM-EVs, was shown to be involved in promoting the osteoclast differentiation [ 70 , 71 ]. It was shown that miR-21 targets the 3′UTR of osteoprotegerin (OPG) mRNA, which in turn, contributes to the imbalance of RANKL/OPG—key players in the physiologic bone remodeling [ 71 ]. Not only miRNAs, but also lncRNAs have been identified in studies as significant in the development of MBD. The transfer of lncRUNX2-AS1 from the MM-EVs to marrow stem cells can inhibit the RUNX2—an essential transcription factor regulating the osteoblast differentiation, which leads to the inhibition of osteogenesis through the interference in the splicing of RUNX2 [ 72 ].
The MM-EVs facilitate the MM cell dissemination also, thanks to their procoagulant content (tissue factor [TF] and procoagulant phospholipids). The components of the EVs lead to the start of the cascade of coagulation, in which platelet activation plays a vital role [ 73 ]. The platelets have been already shown to exert an effect on the metastatic niche through the expression of such cytokines as TGF-β [ 74 ]. Another important platelet-derived cytokine in the MM progression is IL-1β, which has been shown to cause an increased tumor cell engraftment in vivo [ 75 ].
Interestingly, the chemotherapeutics that are used for MM treatment (such as bortezomib, carfilzomib, and melphalan) may increase the osteoclastogenic function of MM-EVs. These drugs increase the level of heparanase in MM-EVs, which in turn activates the cell surface protein, syndecan-1, which interacts with BM-MSCs to promote tumor dissemination. It also activates the ERK pathway which leads to the secretion of osteolytic factors, MMP-9 and RANKL [ 76 ]. Whether this mechanism has a significant clinical impact on the treatment outcome of MM patients remains to be clarified.
2.5. Immunosuppression
The hematopoietic compartment of a BM consists of myeloid cells, T and B lymphocytes, natural killer (NK) cells, and osteoclasts and it is an important factor in an immune response toward malignancy [ 77 ]. A cross-talk between BM cells serves firstly as a killer and then as an inhibitor of malignant development. Interestingly, with tumor progression, it appears that some BM cells cooperate with MM, promoting the immune escape [ 41 , 78 ]. This corresponds with the theory of Schreiber et al., stating that there are three main phases of cancer immunoediting: elimination, equilibrium, and escape [ 79 ]. In the first phase, both innate and adaptive immune systems effectively detect and kill the cancerous cells, but some tumor cell variants might survive it and enter a second phase—equilibrium, where the growth of the tumor is inhibited by the immune system. This phase was observed to be the longest one and some researchers suggest that the benign conditions preceding MM, thus MGUS and SMM, could match with equilibrium [ 80 ].
The immune escape of the tumor might be executed by the transformation of the malignant cell or the immune system of the host. Alterations in the hematopoietic populations were described extensively as possible mechanisms of the immune evasion, both from the innate and adaptive immunities [ 81 , 82 , 83 , 84 , 85 , 86 ]. As mentioned before, microenvironmental factors, such as EVs, could play an essential role in the process.
Indeed, EVs exert a direct effect on the myeloid-derived suppressor cells (MDSCs), increasing their viability and proliferation by up-regulating the STAT3 pathway and increasing the pro-survival proteins B-cell lymphoma-extra-large (Bcl-xL) and myeloid cell leukemia-1 (Mcl-1) [ 41 ]. Moreover, the cargo of MM-EVs includes PGE2 and TGFβ, which stimulate the neoangiogenesis and MDSCs buildup in the tumor site [ 87 ]. When stimulated by the MM-derived EVs, the transition to the highly immunosuppressive subpopulation CD11b+Ly6GlowLy6C+, is induced [ 41 ]. This subclass mediates the immune evasion by overexpressing the inducible nitric oxide synthase (iNOS), which promotes the T-cell inhibition via the induction of hydrogen peroxide and peroxynitrite. These compounds work in various mechanisms, collectively blocking the T cell receptor (TCR) dependent activation of T lymphocytes [ 88 ]. What is more, MM cells, stimulated by EVs, produce an augmented amount of inflammatory cytokines, such as IL6 and VEGF, which further aggravate the MDSCs accumulation, tumor growth, and other immunosuppressive mechanisms, hence inducing a favorable environment for malignancy [ 87 , 89 ].
What is more, MM cells with chromosome 13 deletion (Del13) secrete increased amounts of EVs within which reduced miR-16 levels were detected. When stimulating monocytes, these EVs induced the differentiation to the protumoral M2 macrophage population. miR-16 is a negative modulator of the NF-kB pathway, which is involved in the M2 polarization by inducing the expression of M2-specific cytokines, including IL-10, IL-8, and TNF-α [ 90 ].
Moreover, EVs can also serve as anti-tumor immune response inducers and boosters. As tumor antigen transporters (namely mucin 1 (MUC1), survivin) they can activate the T-cell response mediated by dendritic cells (DC) [ 91 ]. In addition, EVs are well-documented positive modulators of the NK cell response. NK cells might be stimulated by some MM-derived EVs expressing Hsp-70 and interleukin 15 receptor α (IL-15Rα) [ 92 , 93 , 94 ]. Similarly, DC-derived EVs expressing IL-15Rα might trigger the NK cell response [ 95 ]. These immunity-inducing properties of the EVs led to the ongoing research of antitumor EV-based vaccination, which hopefully will be established soon [ 96 ].
2.6. Drug Resistance
Despite the introduction of new therapeutic agents, drug resistance remains one of the biggest problems in MM patients and the median overall survival in triple-class refractory patients is only 5.6 months [ 97 ]. Drug resistance in MM is connected to both adjustments in MM cells (i.e., the upregulation of Pgp [ 98 ], the mutation in the proteasomal system [ 95 ], changes in CD expression [ 99 ]) and the microenvironmental adaptations (environment-mediated drug resistance (EMDR)) where the EV mediated cross-talk is considered to play an important role [ 100 , 101 ].
In previous chapters, we described some of the adaptations that increase MM survival. Indeed, the aforementioned mechanisms play a vital role also in the drug resistance induction, therefore the endurance of the cancer cells. A cross-talk between the endothelial and MM cells leads to the creation of the vascular niche, whereby partial protection from anti-tumor agents is provided [ 102 ]. Furthermore, an interaction between osteoblasts, osteoclasts, and stromal cells prevents the pro-apoptotic actions of the anticancer drugs [ 100 ]. Moreover, the MM-induced immunosuppression impairs the T-cell activity, avoiding the antibody-dependent cell-mediated cytotoxicity (ADCC) [ 41 ].
There are three main groups of anti-myeloma drugs: proteasome inhibitors (i.e., bortezomib, carfilzomib, ixazomib), immunomodulators (i.e., thalidomide, lenalidomide, and pomalidomide), and monoclonal antibodies (daratumumab, elotuzumab, isatuximab). Interestingly, the EV-mediated resistance was described for each group, which shows that EVs play an important role in MM survival ( Figure 4 ).
2.6.1. Proteasome Inhibitors (PI)
Proteasome inhibitors are commonly administered as the first-line treatment in MM patients, as well as in refractory and relapse patients [ 103 ]. These agents bind to the catalytic site of the 26S proteasome, therefore, suppressing its degrading activity and deregulating the ubiquitin-proteasome pathway (UPP) [ 104 ]. This alteration leads to the cellular toxicity in direct (apoptosis induction via JNK and p53 pathways) and indirect mechanisms (reduced degradation of pro-apoptotic molecules) [ 105 ].
It is known that soluble factors derived from BMSC, encourage resistance toward a drug-induced apoptosis [ 106 ]. The mechanism behind this process is linked to the inhibition of caspase-3, caspase-9, and PARP cleavage and therefore the increased viability of the malignant cells in the presence of bortezomib. Interestingly, not only MM BMSC-derived EVs, but also EVs isolated from healthy donors improve the viability of MM cells [ 107 ] ( Figure 4 ).
Moreover, BMSC is not a single population mediating an acquisition of the drug resistance against PI. Stem cell-derived EVs contain lncRNA PSMA3-AS1, which is involved in the positive regulation of the α7 proteasome subunit PSMA3 in MM cells ( Figure 4 ). An augmented expression of both PSMA3 and PSMA3-AS1 mRNA corresponds with the PI resistance, overall survival (OS) and progression-free survival (PFS). Thus, these EVs are being examined as a potential biomarker of MM [ 108 ].
2.6.2. Immunomodulators
The EVs’ ability to transfer drug resistance was also described, regarding immunomodulators. The lenalidomide-sensitive MM cells were able to acquire resistance when cocultured with resistant MM cells. Interestingly, the acquired resistance corresponded with a stronger adherence of the sensitive cell lines. Lenalidomide resistance was correlated with the overexpression of SORT1 and LAMP2 genes that are responsible for a higher EV release ( Figure 4 ). Sadly, no cargo of the EVs was described in the study and the researchers weren’t able to name a specific mechanism binding all of the aforementioned findings together, therefore the topic needs further clarification [ 109 ].
2.6.3. Monoclonal Antibodies
The introduction of monoclonal antibodies in the MM treatment is a great success in the present hematology, improving the overall survival and progression-free survival [ 110 ]. Daratumumab and isatuximab target CD38 while elotuzumab targets SLAMF7, the proteins that are overexpressed on the surface of MM cells [ 111 , 112 ]. However, we need to remember that the content of the EVs corresponds with the parental cell. Indeed, as mentioned before, the vesicles derived from the myeloma cells overexpress CD38, just as the cell of origin [ 113 ]. A study on HER-2-positive breast cancer cells indicated that HER-2-positive EVs can bind to trastuzumab, therefore decreasing the bioavailability of the drug [ 107 ]. In conclusion, it seems possible that MM-derived EVs that express CD38 can have a similar effect on both daratumumab and isatuximab ( Figure 4 ). Less is known about the SLAM family as an EVs cargo, therefore this topic needs further evaluation.
3. Conclusions
As demonstrated in this article, MM is highly dependent on other cells and the cooperation between them is essential for the tumor progression. A cross-talk between cancer and its microenvironment is partially mediated by EVs, which explains a growing interest in this matter worldwide. EVs are abundant in different types of cargo. They can contain molecules, such as proteins, cytokines, chemokines, miRNA, lncRNA, and more [ 39 , 47 , 53 , 54 ]. A further elaboration on the precise relationship between cancer and EVs is necessary as it might lead to the invention of new cancer therapeutic strategies in the future. The knowledge about the EVs’ involvement in the pathogenesis of MM might add up significantly to the already ongoing works concerning a dendritic cell-based vaccination in MM [ 91 , 114 ], as it has been demonstrated in the case of the tumor-derived EVs’ influence on immunointerventions against melanoma [ 115 ]. Another possible therapeutic approach could repose on the role of apoEVs, derived from MSCs. They have been shown to induce the Fas-mediated apoptosis of MM cells in a mouse model, thus, prolonging the life span of MM mice [ 116 ].
An increasing number of studies concerning EVs in the pathogenesis of multiple myeloma is an indicator of their importance in modern research. Indeed, some unexpected results were published concerning EVs, which 30 years ago were considered cellular debris. Various studies bring more and more clarity, as far as the structure and cargo of EVs are concerned. Despite the statement from the International Society for Extracellular Vesicles and the updated guidelines, the approach toward the research on EVs is not unified and the nomenclature and study designs lack the needed consistency. Perhaps, the guidelines that will be published this year might prove to be of significance in this matter. The improvement of the tools for better EV differentiation and collecting is also needed. Better methods will allow more precise analysis of such a vast topic as EVs.
EVs have been detected in different body fluids, such as blood plasma [ 117 ], saliva [ 118 ], bronchoalveolar fluid [ 119 ], cerebrospinal fluid [ 120 ], to name a few. EVs contain different molecules, which could reflect the pathogenesis and progression of a disease, even at an early stage [ 121 , 122 ]. What is more, EVs can be detected using minimally invasive procedures, which is advantageous for multiple reasons, the possible shortening of the time of the diagnostic pathway, a faster implementation of therapy, the possibility of patients, who otherwise would be unfit for certain invasive diagnostic procedures to obtain a thorough diagnosis, and lastly, the economic reasons, including the lowered costs of diagnosis and follow-up. The use of modern techniques, such as phage display technology, in the identification of EVs, which has recently been demonstrated on an animal model, might lead to a less invasive and more personalized diagnostic process [ 123 ]. Thanks to these characteristics, EVs could be employed in everyday practice as a perfect tool for early detection as well as a marker of the progression of a disease. As far as the research in MM EVs is concerned, a different EV cargo expression and a difference in the quantity of EVs between MGUS, SMM, MM, and healthy donors, have been shown [ 124 , 125 ]. What is more, a recent study identified certain miRNA from circulating EVs (namely miR-18a and Let-7 microRNA precursor) as a prognostic marker of MM [ 126 ]. These findings suggest that circulating EVs could constitute a novel marker of the MM progression and possibly a diagnostic marker in a more distant future. This, in turn, would surely diminish the effects of a bone marrow biopsy, an invasive procedure that can be aggravating, especially for the elderly people that count as the biggest myeloma patients’ group. A marker that could not only distinguish MM from other conditions but also demonstrate the stage of the disease would positively influence the quality of life of multiple myeloma patients.
To summarize, the article presents the rising importance of EVs in the understanding of MM pathogenesis. Hopefully, when better understood, EVs might serve as a useful tool in the diagnosis and treatment of MM patients.
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Author Contributions
J.I., P.Z., I.M.-K. and B.P. wrote and reviewed the manuscript. J.I. and P.Z. contributed equally to this work. All authors have read and agreed to the published version of the manuscript.
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
Not applicable.
Conflicts of Interest
The authors declare no conflict of interest.
Abbreviations
The following abbreviations are used in this manuscript: ADCC antibody-dependent cell-mediated cytotoxicity Akt protein kinase B ApoBDs apoptotic bodies ApoEVs apoptotic extracellular vesicles ApoExos apoptotic exosomes ApoMVs apoptotic microvesicles AREG amphiregulin ARMM ARRDC1-mediated microvesicle ARRDC1 arrestin-domain-containing protein 1 α-SMA α-smooth muscle actin BCL B-cell lymphoma gene Bcl-xL B-cell lymphoma-extra large Bi-EVs MM-EVs pre-treated with bortezomib BM bone marrow BM-MSC bone marrow mesenchymal stromal cells BMPs bone morphogenetic proteins β-TRC β-transducin CAFs carcinoma-associated fibroblasts CCL CC chemokine ligand CTSK Cathepsin K CXCL CXC ligand CXCR CXC chemokine receptor DC dendritic cell Del13 chromosome 13 deletion DKK1 Dickkopf-related protein 1 EC-EVs endothelial cells-derived extracellular vesicles ECs endothelial cells EGFR epithelial growth factor receptor eiF4GI eukaryotic translation initiation factor 4GI EMDR environment-mediated drug resistance EphA8 ephrin receptor A8 kinase ERK extracellular signal-regulated kinases ESCRT endosomal sorting complexes required for transport EVs extracellular vesicles FAP fibroblast-activated protein FIH-1 factor-inhibiting hypoxia-inducible factor 1 HER-2 human epidermal growth factor receptor 2 HR-MM cells hypoxia-resistant multiple myeloma cells Hsp-70 heat shock protein 70 IL interleukin IL-15Rα interleukin 15 receptor α ILVs intraluminal vesicles iNOS inducible nitric oxide synthase IP-10 interferon-γ–inducible protein 10 ISEV International Society for Extracellular Vesicles JNK c-Jun N-terminal kinase JUP junction plakoglobin LAMP2 lysosomal associated membrane protein 2 LINC00461 long intergenic non-protein coding RNA 461 lncRNAs long-non-coding RNAs MAPK mitogen-activated protein kinase MBD myeloma-associated bone disease Mcl-1 myeloid cell leukemia-1 MDSCs myeloid-derived suppressor cells MGUS monoclonal gammopathy of undetermined significance miR microRNA MM multiple myeloma MM MSC multiple myeloma mesenchymal stromal cells MM-EVs multiple myeloma-derived extracellular vesicles MMPs metalloproteinases MUC-1 mucin 1 MVB multivesicular body MVs microvesicles NFkB nuclear factor kappa-light-chain-enhancer of activated B cells NK natural killer NKG2DLs natural-killer group 2, member D OBs osteoblasts OCs osteoclasts OPG osteoprotegerin PDGF-BB platelet-derived growth factor-BB PGE2 prostaglandin E2 Pgp P-glycoprotein PI3K phosphoinositide 3-kinase piRNA PIWI-interacting RNA PM plasma membrane RANKL receptor activator for nuclear factor κ B ligand RHO GTPase Ras homologous GTPase RUNX2 Runt-related transcription factor 2 SDF-1 stromal-derived factor 1 SEMA5A human Semaphorin-5A SLAM signaling lymphocytic activation molecule SMAD5 SMAD family member 5 SMM smoldering multiple myeloma SORT1 sortilin1 STAT3 signal transducer and activator of transcription 3 TCR T cell receptor TF tissue factor TGF-β tumor growth factor-β TRAP thrombospondin-related anonymous protein uPAR urokinase plasminogen activator receptor UPP ubiquitin-proteasome pathway VEGF vascular endothelial growth factor-1
References
1. Brigle K. Rogers B. Pathobiology and Diagnosis of Multiple Myeloma Semin. Oncol. Nurs. 2017 33 225 236 10.1016/j.soncn.2017.05.012 28688533
2. National Cancer Institute Surveillance, Epidemiology, and End Result Program Cancer Stat Facts Myeloma Available online: https://seer.cancer.gov/statfacts/html/mulmy.html (accessed on 13 August 2022)
3. Saltarella I. Lamanuzzi A. Apollonio B. Desantis V. Bartoli G. Vacca A. Frassanito M.A. Role of Extracellular Vesicle-Based Cell-to-Cell Communication in Multiple Myeloma Progression Cells 2021 10 3185 10.3390/cells10113185 34831408 PMC8625088
4. Ho M. Patel A. Goh C.Y. Moscvin M. Zhang L. Bianchi G. Changing paradigms in diagnosis and treatment of monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM) Leukemia 2020 34 3111 3125 10.1038/s41375-020-01051-x 33046818
5. Landgren O. Kyle R.A. Pfeiffer R.M. Katzmann J.A. Caporaso N.E. Hayes R. Dispenzieri A. Kumar S. Clark R.J. Baris D. Monoclonal gammopathy of undetermined significance (MGUS) consistently precedes multiple myeloma: A prospective study Blood 2009 113 5412 5417 10.1182/blood-2008-12-194241 19179464 PMC2689042
6. Rajkumar S.V. Dimopoulos M.A. Palumbo A. Blade J. Merlini G. Mateos M.-V. Kumar S. Hillengass J. Kastritis E. Richardson P. International Myeloma Working Group updated criteria for the diagnosis of multiple myeloma Lancet Oncol. 2014 15 e538 e548 10.1016/S1470-2045(14)70442-5 25439696
7. Kyle R.A. Remstein E.D. Therneau T.M. Dispenzieri A. Kurtin P.J. Hodnefield J.M. Larson D.R. Plevak M.F. Jelinek D.F. Fonseca R. Clinical Course and Prognosis of Smoldering (Asymptomatic) Multiple Myeloma N. Engl. J. Med. 2007 356 2582 2590 10.1056/NEJMoa070389 17582068
8. Brinton L.T. Sloane H.S. Kester M. Kelly K.A. Formation and role of exosomes in cancer Cell. Mol. Life Sci. 2014 72 659 671 10.1007/s00018-014-1764-3 25336151 PMC5489338
9. Bebelman M.P. Smit M.J. Pegtel D.M. Baglio S.R. Biogenesis and function of extracellular vesicles in cancer Pharmacol. Ther. 2018 188 1 11 10.1016/j.pharmthera.2018.02.013 29476772
10. Rufino-Ramos D. Albuquerque P.R. Carmona V. Perfeito R. Nobre R.J. de Almeida L.P. Extracellular vesicles: Novel promising delivery systems for therapy of brain diseases J. Control. Release 2017 262 247 258 10.1016/j.jconrel.2017.07.001 28687495
11. Manna I. Quattrone A. De Benedittis S. Vescio B. Iaccino E. Quattrone A. Exosomal miRNA as peripheral biomarkers in Parkinson’s disease and progressive supranuclear palsy: A pilot study Park. Relat. Disord. 2021 93 77 84 10.1016/j.parkreldis.2021.11.020 34839044
12. Tian T. Cao L. He C. Ye Q. Liang R. You W. Zhang H. Wu J. Ye J. Tannous B.A. Targeted delivery of neural progenitor cell-derived extracellular vesicles for anti-inflammation after cerebral ischemia Theranostics 2021 11 6507 6521 10.7150/thno.56367 33995671 PMC8120222
13. Liu C. Bayado N. He D. Li J. Chen H. Li L. Li J. Long X. Du T. Tang J. Therapeutic Applications of Extracellular Vesicles for Myocardial Repair Front. Cardiovasc. Med. 2021 8 758050 10.3389/fcvm.2021.758050 34957249 PMC8695616
14. Femminò S. Penna C. Margarita S. Comità S. Brizzi M.F. Pagliaro P. Extracellular vesicles and cardiovascular system: Biomarkers and Cardioprotective Effectors Vasc. Pharmacol. 2020 135 106790 10.1016/j.vph.2020.106790 32861822
15. Kubo H. Extracellular Vesicles in Lung Disease Chest 2017 153 210 216 10.1016/j.chest.2017.06.026 28684288
16. Théry C. Witwer K.W. Aikawa E. Alcaraz M.J. Anderson J.D. Andriantsitohaina R. Antoniou A. Arab T. Archer F. Atkin-Smith G.K. Minimal information for studies of extracellular vesicles 2018 (MISEV2018): A position statement of the International Society for Extracellular Vesicles and update of the MISEV2014 guidelines J. Extracell. Vesicles 2018 7 1535750 10.1080/20013078.2018.1535750 30637094 PMC6322352
17. Dibavar M.A. Pourbagheri-Sigaroodi A. Asemani Y. Salari S. Bashash D. Extracellular vesicles (EVs): What we know of the mesmerizing roles of these tiny vesicles in hematological malignancies? Life Sci. 2021 271 119177 10.1016/j.lfs.2021.119177 33577843
18. Van Niel G. D’Angelo G. Raposo G. Shedding light on the cell biology of extracellular vesicles Nat. Rev. Mol. Cell Biol. 2018 19 213 228 10.1038/nrm.2017.125 29339798
19. Caruso S. Poon I.K.H. Apoptotic Cell-Derived Extracellular Vesicles: More Than Just Debris Front. Immunol. 2018 9 1486 10.3389/fimmu.2018.01486 30002658 PMC6031707
20. Kakarla R. Hur J. Kim Y.J. Kim J. Chwae Y.-J. Apoptotic cell-derived exosomes: Messages from dying cells Exp. Mol. Med. 2020 52 1 6 10.1038/s12276-019-0362-8 31915368 PMC7000698
21. Poon I.K.H. Parkes M.A.F. Jiang L. Atkin-Smith G.K. Tixeira R. Gregory C.D. Ozkocak D.C. Rutter S.F. Caruso S. Santavanond J.P. Moving beyond size and phosphatidylserine exposure: Evidence for a diversity of apoptotic cell-derived extracellular vesicles in vitro J. Extracell. Vesicles 2019 8 1608786 10.1080/20013078.2019.1608786 31069027 PMC6493268
22. Jeppesen D.K. Fenix A.M. Franklin J.L. Higginbotham J.N. Zhang Q. Zimmerman L.J. Liebler D.C. Ping J. Liu Q. Evans R. Reassessment of Exosome Composition Cell 2019 177 428 445.e18 10.1016/j.cell.2019.02.029 30951670 PMC6664447
23. Bolli N. Maura F. Minvielle S. Gloznik D. Szalat R. Fullam A. Martincorena I. Dawson K.J. Samur M.K. Zamora J. Genomic patterns of progression in smoldering multiple myeloma Nat. Commun. 2018 9 3363 10.1038/s41467-018-05058-y 30135448 PMC6105687
24. Roccaro A.M. Sacco A. Maiso P. Azab A.K. Tai Y.T. Reagan M. Azab F. Flores L.M. Campigotto F. Weller E. BM mesenchymal stromal cell-derived exosomes facilitate multiple myeloma progression J. Clin. Investig. 2013 123 1542 1555 10.1172/JCI66517 23454749 PMC3613927
25. Deng M. Yuan H. Liu S. Hu Z. Xiao H. Exosome-transmitted LINC00461 promotes multiple myeloma cell proliferation and suppresses apoptosis by modulating microRNA/BCL-2 expression Cytotherapy 2019 21 96 106 10.1016/j.jcyt.2018.10.006 30409700
26. Cimmino A. Calin G.A. Fabbri M. Iorio M.V. Ferracin M. Shimizu M. Wojcik S.E. Aqeilan R.I. Zupo S. Dono M. miR-15 and miR-16 induce apoptosis by targeting BCL2 Proc. Natl. Acad. Sci. USA 2005 102 13944 13949 10.1073/pnas.0506654102 16166262 PMC1236577
27. Cheng Q. Li X. Liu J. Ye Q. Chen Y. Tan S. Liu J. Multiple Myeloma-Derived Exosomes Regulate the Functions of Mesenchymal Stem Cells Partially via Modulating miR-21 and miR-146a Stem Cells Int. 2017 2017 9012152 10.1155/2017/9012152 29333170 PMC5733127
28. De Veirman K. Wang J. Xu S. Leleu X. Himpe E. Maes K. De Bruyne E. van Valckenborgh E. Vanderkerken K. Menu E. Induction of miR-146a by multiple myeloma cells in mesenchymal stromal cells stimulates their pro-tumoral activity Cancer Lett. 2016 377 17 24 10.1016/j.canlet.2016.04.024 27102001
29. Umezu T. Imanishi S. Yoshizawa S. Kawana C. Ohyashiki J.H. Ohyashiki K. Induction of multiple myeloma bone marrow stromal cell apoptosis by inhibiting extracellular vesicle miR-10a secretion Blood Adv. 2019 3 3228 3240 10.1182/bloodadvances.2019000403 31698453 PMC6855114
30. Wang D. Zhang P. Gao K. Tang Y. Jin X. Zhang Y. Yi Q. Wang C. Yu L. PLK1 and β-TrCP-dependent ubiquitination and degradation of Rap1GAP controls cell proliferation PLoS ONE 2014 9 e110296 10.1371/journal.pone.0110296 25329897 PMC4201484
31. Peng Y. Song X. Lan J. Wang X. Wang M. Bone marrow stromal cells derived exosomal miR-10a and miR-16 may be involved in progression of patients with multiple myeloma by regulating EPHA8 or IGF1R/CCND1 Medicine 2021 100 e2344 10.1097/MD.0000000000023447 PMC7850735 33530159
32. Dabbah M. Attar-Schneider O. Tartakover Matalon S. Shefler I. Jarchwsky Dolberg O. Lishner M. Drucker L. Microvesicles derived from normal and multiple myeloma bone marrow mesenchymal stem cells differentially modulate myeloma cells’ phenotype and translation initiation Carcinogenesis 2017 38 708 716 10.1093/carcin/bgx045 28838065
33. Arendt B.K. Walters D.K. Wu X. Tschumper R.C. Jelinek D.F. Multiple myeloma dell-derived microvesicles are enriched in CD147 expression and enhance tumor cell proliferation Oncotarget 2014 5 5686 5699 10.18632/oncotarget.2159 25015330 PMC4170605
34. Shen Y.J. Mishima Y. Shi J. Sklavenitis-Pistofidis R. Redd R.A. Moschetta M. Manier S. Roccaro A.M. Sacco A. Tai Y.-T. Progression signature underlies clonal evolution and dissemination of multiple myeloma Blood 2021 137 2360 2372 10.1182/blood.2020005885 33150374 PMC8085483
35. Hu Y. Lin J. Fang H. Fang J. Li C. Chen W. Liu S. Ondrejka S. Gong Z. Reu F. Targeting the MALAT1/PARP1/LIG3 complex induces DNA damage and apoptosis in multiple myeloma Leukemia 2018 32 2250 2262 10.1038/s41375-018-0104-2 29632340 PMC6151178
36. Ogiya D. Liu J. Ohguchi H. Kurata K. Samur M.K. Tai Y.T. Adamia S. Ando K. Hideshima T. Anderson K.C. The JAK-STAT pathway regulates CD38 on myeloma cells in the bone marrow microenvironment: Therapeutic implications Blood 2020 136 2334 2345 10.1182/blood.2019004332 32844992 PMC7702477
37. Raje N.S. Bhatta S. Terpos E. Role of the RANK/RANKL Pathway in Multiple Myeloma Clin. Cancer Res. 2019 25 12 20 10.1158/1078-0432.CCR-18-1537 30093448
38. Henrich S.E. McMahon K.M. Plebanek M.P. Calvert A.E. Feliciano T.J. Parrish S. Tavora F. Mega A. De Souza A. Carneiro B.A. Prostate cancer extracellular vesicles mediate intercellular communication with bone marrow cells and promote metastasis in a cholesterol-dependent manner J. Extracell. Vesicles 2020 10 e12042 10.1002/jev2.12042 33408816 PMC7775568
39. Tian Y. Ma L. Gong M. Su G. Zhu S. Zhang W. Wang S. Li Z. Chen C. Li L. Protein Profiling and Sizing of Extracellular Vesicles from Colorectal Cancer Patients via Flow Cytometry ACS Nano 2018 12 671 680 10.1021/acsnano.7b07782 29300458
40. Yang N. Li S. Li G. Zhang S. Tang X. Ni S. Jian X. Xu C. Zhu J. Lu M. The role of extracellular vesicles in mediating progression, metastasis and potential treatment of hepatocellular carcinoma Oncotarget 2017 8 3683 3695 10.18632/oncotarget.12465 27713136 PMC5356911
41. Wang J. De Veirman K. Faict S. Frassanito M.A. Ribatti D. Vacca A. Menu E. Multiple myeloma exosomes establish a favourable bone marrow microenvironment with enhanced angiogenesis and immunosuppression J. Pathol. 2016 239 162 173 10.1002/path.4712 26956697
42. Colombo M. Galletti S. Bulfamante G. Falleni M. Tosi D. Todoerti K. Lazzari E. Crews L.A. Jamieson C.H. Ravaioli S. Multiple myeloma-derived Jagged ligands increases autocrine and paracrine interleukin-6 expression in bone marrow niche Oncotarget 2016 7 56013 56029 10.18632/oncotarget.10820 27463014 PMC5302893
43. Colombo M. Giannandrea D. Lesma E. Basile A. Chiaramonte R. Extracellular Vesicles Enhance Multiple Myeloma Metastatic Dissemination Int. J. Mol. Sci. 2019 20 3236 10.3390/ijms20133236 31266187 PMC6650870
44. Zhang L. Lei Q. Wang H. Xu C. Liu T. Kong F. Yang C. Yan G. Sun L. Zhao A. Tumor-derived extracellular vesicles inhibit osteogenesis and exacerbate myeloma bone disease Theranostics 2019 9 196 209 10.7150/thno.27550 30662562 PMC6332790
45. Purushothaman A. Bandari S.K. Liu J. Mobley J.A. Brown E.E. Sanderson R.D. Fibronectin on the Surface of Myeloma Cell-derived Exosomes Mediates Exosome-Cell Interactions J. Biol. Chem. 2016 291 1652 1663 10.1074/jbc.M115.686295 26601950 PMC4722448
46. Bochmann I. Ebstein F. Lehmann A. Wohlschlaeger J. Sixt S.U. Kloetzel P.-M. Dahlmann B. T lymphocytes export proteasomes by way of microparticles: A possible mechanism for generation of extracellular proteasomes J. Cell. Mol. Med. 2014 18 59 68 10.1111/jcmm.12160 24304442 PMC3916118
47. Umezu T. Tadokoro H. Azuma K. Yoshizawa S. Ohyashiki K. Ohyashiki J.H. Exosomal miR-135b shed from hypoxic multiple myeloma cells enhances angiogenesis by targeting factor-inhibiting HIF-1 Blood 2014 124 3748 3757 10.1182/blood-2014-05-576116 25320245 PMC4263983
48. Jakob C. Egerer K. Liebisch P. Türkmen S. Zavrski I. Kuckelkorn U. Heider U. Kaiser M. Fleissner C. Sterz J. Circulating proteasome levels are an independent prognostic factor for survival in multiple myeloma Blood 2007 109 2100 2105 10.1182/blood-2006-04-016360 17095627
49. Semenza G.L. Targeting HIF-1 for cancer therapy Nat. Cancer 2003 3 721 732 10.1038/nrc1187 13130303
50. Zarfati M. Avivi I. Brenner B. Katz T. Aharon A. Extracellular vesicles of multiple myeloma cells utilize the proteasome inhibitor mechanism to moderate endothelial angiogenesis Angiogenesis 2018 22 185 196 10.1007/s10456-018-9649-y 30386953
51. Chouaib S. Umansky V. Kieda C. The role of hypoxia in shaping the recruitment of proangiogenic and immunosuppressive cells in the tumor microenvironment Contemp. Oncol. 2018 22 7 13 10.5114/wo.2018.73874 PMC5885081 29628788
52. Gastelum G. Veena M. Lyons K. Lamb C. Jacobs N. Yamada A. Baibussinov A. Sarafyan M. Shamis R. Kraut J. Can Targeting Hypoxia-Mediated Acidification of the Bone Marrow Microenvironment Kill Myeloma Tumor Cells? Front. Oncol. 2021 11 703878 10.3389/fonc.2021.703878 34350119 PMC8327776
53. Li B. Hong J. Hong M. Wang Y. Yu T. Zang S. Wu Q. piRNA-823 delivered by multiple myeloma-derived extracellular vesicles promoted tumorigenesis through re-educating endothelial cells in the tumor environment Oncogene 2019 38 5227 5238 10.1038/s41388-019-0788-4 30890754
54. Choi H.Y. Moon S.J. Ratliff B.B. Ahn S.H. Jung A. Lee M. Lee S. Lim B.J. Kim B.S. Plotkin M.D. Microparticles from Kidney-Derived Mesenchymal Stem Cells Act as Carriers of Proangiogenic Signals and Contribute to Recovery from Acute Kidney Injury PLoS ONE 2014 9 e87853 10.1371/journal.pone.0087853 24504266 PMC3913695
55. Zou X. Gu D. Xing X. Cheng Z. Gong D. Zhang G. Zhu Y. Human mesenchymal stromal cell-derived extracellular vesicles alleviate renal ischemic reperfusion injury and enhance angiogenesis in rats Am. J. Transl. Res. 2016 8 4289 4299 27830012 PMC5095321
56. Andersen N.F. Kristensen I.B. Preiss B.S. Christensen J.H. Abildgaard N. Upregulation of Syndecan-1 in the bone marrow microenvironment in multiple myeloma is associated with angiogenesis Eur. J. Haematol. 2015 95 211 217 10.1111/ejh.12473 25353275
57. Taraboletti G. D’Ascenzo S. Borsotti P. Giavazzi R. Pavan A. Dolo V. Shedding of the matrix metalloproteinases MMP-2, MMP-9, and MT1-MMP as membrane vesicle-associated components by endothelial cells Am. J. Pathol. 2002 160 673 680 10.1016/S0002-9440(10)64887-0 11839588 PMC1850663
58. Lombardo G. Dentelli P. Togliatto G. Rosso A. Gili M. Gallo S. Deregibus M.C. Camussi G. Brizzi M.F. Activated Stat5 trafficking Via Endothelial Cell-derived Extracellular Vesicles Controls IL-3 Pro-angiogenic Paracrine Action Sci. Rep. 2016 6 25689 10.1038/srep25689 27157262 PMC4860593
59. Theofilis P. Vogiatzi G. Oikonomou E. Gazouli M. Siasos G. Katifelis H. Perrea D. Vavuranakis M. Iliopoulos D.C. Tsioufis C. The Effect of MicroRNA-126 Mimic Administration on Vascular Perfusion Recovery in an Animal Model of Hind Limb Ischemia Front. Mol. Biosci. 2021 8 724465 10.3389/fmolb.2021.724465 34513927 PMC8423909
60. Ghafouri-Fard S. Abak A. Anamag F.T. Shoorei H. Majidpoor J. Taheri M. The emerging role of non-coding RNAs in the regulation of PI3K/AKT pathway in the carcinogenesis process Biomed. Pharmacother. 2021 137 111279 10.1016/j.biopha.2021.111279 33493969
61. Sleeman J.P. Christofori G. Fodde R. Collard J.G. Berx G. Decraene C. Rüegg C. Concepts of metastasis in flux: The stromal progression model Semin. Cancer Biol. 2012 22 174 186 10.1016/j.semcancer.2012.02.007 22374376
62. Migliorini F. Maffulli N. Trivellas A. Eschweiler J. Tingart M. Driessen A. Bone metastases: A comprehensive review of the literature Mol. Biol. Rep. 2020 47 6337 6345 10.1007/s11033-020-05684-0 32749632
63. Rasch S. Lund T. Asmussen J. Nielsen A.L. Larsen R.F. Andersen M. Abildgaard N. Multiple Myeloma Associated Bone Disease Cancers 2020 12 2113 10.3390/cancers12082113 32751464 PMC7465468
64. Shupp A. Kolb A. Mukhopadhyay D. Bussard K. Cancer Metastases to Bone: Concepts, Mechanisms, and Interactions with Bone Osteoblasts Cancers 2018 10 182 10.3390/cancers10060182 29867053 PMC6025347
65. Faict S. Muller J. De Veirman K. De Bruyne E. Maes K. Vrancken L. Heusschen R. De Raeve H. Schots R. Vanderkerken K. Exosomes play a role in multiple myeloma bone disease and tumor development by targeting osteoclasts and osteoblasts Blood Cancer J. 2018 8 105 10.1038/s41408-018-0139-7 30409995 PMC6224554
66. Berasain C. Avila M.A. Amphiregulin Semin. Cell Dev. Biol. 2014 28 31 41 10.1016/j.semcdb.2014.01.005 24463227
67. Raimondo S. Saieva L. Vicario E. Pucci M. Toscani D. Manno M. Raccosta S. Giuliani N. Alessandro R. Multiple myeloma-derived exosomes are enriched of amphiregulin (AREG) and activate the epidermal growth factor pathway in the bone microenvironment leading to osteoclastogenesis J. Hematol. Oncol. 2019 12 2 10.1186/s13045-018-0689-y 30621731 PMC6325886
68. Raimondi L. De Luca A. Amodio N. Manno M. Raccosta S. Taverna S. Bellavia D. Naselli F. Fontana S. Schillaci O. Involvement of multiple myeloma cell-derived exosomes in osteoclast differentiation Oncotarget 2015 6 13772 13789 10.18632/oncotarget.3830 25944696 PMC4537049
69. Watanabe T. Realization of Osteolysis, Angiogenesis, Immunosuppression, and Drug Resistance by Extracellular Vesicles: Roles of RNAs and Proteins in Their Cargoes and of Ectonucleotidases of the Immunosuppressive Adenosinergic Noncanonical Pathway in the Bone Marrow Niche of Multiple Myeloma Cancers 2021 13 2969 34199285 10.3390/cancers13122969 PMC8231946
70. Löffler D. Brocke-Heidrich K. Pfeifer G. Stocsits C. Hackermüller J. Kretzschmar A.K. Burger R. Gramatzki M. Blumert C. Bauer K. Interleukin-6–dependent survival of multiple myeloma cells involves the Stat3-mediated induction of microRNA-21 through a highly conserved enhancer Blood 2007 110 1330 1333 10.1182/blood-2007-03-081133 17496199
71. Pitari M.R. Rossi M. Amodio N. Botta C. Morelli E. Federico C. Gullà A. Caracciolo D. Di Martino M.T. Arbitrio M. Inhibition of miR-21 restores RANKL/OPG ratio in multiple myeloma-derived bone marrow stromal cells and impairs the resorbing activity of mature osteoclasts Oncotarget 2015 6 27343 27358 10.18632/oncotarget.4398 26160841 PMC4694994
72. Li B. Xu H. Han H. Song S. Zhang X. Ouyang L. Qian C. Hong Y. Qiu Y. Zhou W. Exosome-mediated transfer of lncRUNX2-AS1 from multiple myeloma cells to MSCs contributes to osteogenesis Oncogene 2018 37 5508 5519 10.1038/s41388-018-0359-0 29895968
73. Nielsen T. Kristensen S.R. Gregersen H. Teodorescu E.M. Christiansen G. Pedersen S. Extracellular vesicle-associated procoagulant phospholipid and tissue factor activity in multiple myeloma PLoS ONE 2019 14 e0210835 10.1371/journal.pone.0210835 30640949 PMC6331130
74. Labelle M. Begum S. Hynes R.O. Platelets guide the formation of early metastatic niches Proc. Natl. Acad. Sci. USA 2014 111 E3053 E3061 10.1073/pnas.1411082111 25024172 PMC4121772
75. Takagi S. Tsukamoto S. Park J. Johnson K.E. Kawano Y. Moschetta M. Liu C.-J. Mishima Y. Kokubun K. Manier S. Platelets Enhance Multiple Myeloma Progression via IL-1β Upregulation Clin. Cancer Res. 2018 24 2430 2439 10.1158/1078-0432.CCR-17-2003 29440174
76. Tripathi K. Ramani V.C. Bandari S.K. Amin R. Brown E.E. Ritchie J.P. Stewart M.D. Sanderson R.D. Heparanase promotes myeloma stemness and in vivo tumorigenesis Matrix Biol. 2019 88 53 68 10.1016/j.matbio.2019.11.004 31812535 PMC7261637
77. Kawano Y. Moschetta M. Manier S. Glavey S. Görgün G.T. Roccaro A.M. Anderson K.C. Ghobrial I.M. Targeting the bone marrow microenvironment in multiple myeloma Immunol. Rev. 2015 263 160 172 10.1111/imr.12233 25510276
78. Wang J. De Veirman K. De Beule N. Maes K. De Bruyne E. van Valckenborgh E. Vanderkerken K. Menu E. The bone marrow microenvironment enhances multiple myeloma progression by exosome-mediated activation of myeloid-derived suppressor cells Oncotarget 2015 6 43992 44004 10.18632/oncotarget.6083 26556857 PMC4791281
79. Schreiber R.D. Old L.J. Smyth M.J. Cancer Immunoediting: Integrating Immunity’s Roles in Cancer Suppression and Promotion Science 2011 331 1565 1570 10.1126/science.1203486 21436444
80. Nakamura K. Smyth M.J. Martinet L. Cancer immunoediting and immune dysregulation in multiple myeloma Blood 2020 136 2731 2740 10.1182/blood.2020006540 32645135
81. Chan A.C. Neeson P. Leeansyah E. Tainton K. Quach H. Prince H.M. Harrison S.J. Godfrey I.D. Ritchie D. Berzins S.P. Natural killer T cell defects in multiple myeloma and the impact of lenalidomide therapy Clin. Exp. Immunol. 2014 175 49 58 10.1111/cei.12196 24032527 PMC3898554
82. Chung D.J. Pronschinske K.B. Shyer J.A. Sharma S. Leung S. Curran S.A. Lesokhin A.M. Devlin S.M. Giralt S.A. Young J.W. T-cell Exhaustion in Multiple Myeloma Relapse after Autotransplant: Optimal Timing of Immunotherapy Cancer Immunol. Res. 2016 4 61 71 10.1158/2326-6066.CIR-15-0055 26464015 PMC4703436
83. Dhodapkar M.V. Krasovsky J. Osman K. Geller M.D. Vigorous Premalignancy-specific Effector T Cell Response in the Bone Marrow of Patients with Monoclonal Gammopathy J. Exp. Med. 2003 198 1753 1757 10.1084/jem.20031030 14638846 PMC2194131
84. Guillerey C. Ferrari de Andrade L. Vuckovic S. Miles K. Ngiow S.F. Yong M.C. Teng M.W. Colonna M. Ritchie D.S. Chesi M. Immunosurveillance and therapy of multiple myeloma are CD226 dependent J. Clin. Investig. 2015 125 2077 2089 10.1172/JCI77181 25893601 PMC4463191
85. Jurisic V. Srdic T. Konjevic G. Markovic O. Colovic M. Clinical stage-depending decrease of NK cell activity in multiple myeloma patients Med Oncol. 2007 24 312 317 10.1007/s12032-007-0007-y 17873307
86. Malek E. de Lima M. Letterio J.J. Kim B.-G. Finke J.H. Driscoll J.J. Giralt S.A. Myeloid-derived suppressor cells: The green light for myeloma immune escape Blood Rev. 2016 30 341 348 10.1016/j.blre.2016.04.002 27132116 PMC6411302
87. Xiang X. Poliakov A. Liu C. Liu Y. Deng Z.-B. Wang J. Cheng Z. Shah S.V. Wang G.-J. Zhang L. Induction of myeloid-derived suppressor cells by tumor exosomes Int. J. Cancer 2009 124 2621 2633 10.1002/ijc.24249 19235923 PMC2757307
88. Gabrilovich D.I. Ostrand-Rosenberg S. Bronte V. Coordinated regulation of myeloid cells by tumours Nat. Rev. Immunol. 2012 12 253 268 10.1038/nri3175 22437938 PMC3587148
89. Weber R. Groth C. Lasser S. Arkhypov I. Petrova V. Altevogt P. Utikal J. Umansky V. IL-6 as a major regulator of MDSC activity and possible target for cancer immunotherapy Cell. Immunol. 2020 359 104254 10.1016/j.cellimm.2020.104254 33296753
90. Khalife J. Ghose J. Martella M. Viola D. Rocci A. Troadec E. Terrazas C. Satoskar A.R. Gunes E.G. Dona A. MiR-16 regulates crosstalk in NF-κB tolerogenic inflammatory signaling between myeloma cells and bone marrow macrophages JCI Insight 2019 4 e129348 10.1172/jci.insight.129348 31593552 PMC6948777
91. Leaf R.K. Stroopinsky D. Pyzer A.R. Kruisbeek A.M. van Wetering S. Washington A. Ephraim A. Cole L. Morin A. Jain S. DCOne as an Allogeneic Cell-based Vaccine for Multiple Myeloma J. Immunother. 2017 40 315 322 10.1097/CJI.0000000000000185 28961609
92. Vulpis E. Cecere F. Molfetta R. Soriani A. Fionda C. Peruzzi G. Caracciolo G. Palchetti S. Masuelli L. Simonelli L. Genotoxic stress modulates the release of exosomes from multiple myeloma cells capable of activating NK cell cytokine production: Role of HSP70/TLR2/NF-kB axis Oncoimmunology 2017 6 e1279372 10.1080/2162402X.2017.1279372 28405503 PMC5384384
93. Borrelli C. Ricci B. Vulpis E. Fionda C. Ricciardi M.R. Petrucci M.T. Masuelli L. Peri A. Cippitelli M. Zingoni A. Drug-Induced Senescent Multiple Myeloma Cells Elicit NK Cell Proliferation by Direct or Exosome-Mediated IL15 Trans-Presentation Cancer Immunol. Res. 2018 6 860 869 10.1158/2326-6066.CIR-17-0604 29691234
94. Elsner L. Muppala V. Gehrmann M. Lozano-Kuehne J. Malzahn D. Bickeböller H. Brunner E. Zientkowska M. Herrmann T. Walter L. The Heat Shock Protein HSP70 Promotes Mouse NK Cell Activity against Tumors That Express Inducible NKG2D Ligands J. Immunol. 2007 179 5523 5533 10.4049/jimmunol.179.8.5523 17911639
95. Viaud S. Terme M. Flament C. Taieb J. André F. Novault S. Escudier B. Robert C. Caillat-Zucman S. Tursz T. Dendritic cell-derived exosomes promote natural killer cell activation and proliferation: A role for NKG2D ligands and IL-15Ralpha PLoS ONE 2009 4 e4942 10.1371/journal.pone.0004942 19319200 PMC2657211
96. Escudier B. Dorval T. Chaput N. André F. Caby M.-P. Novault S. Flament C. Leboulaire C. Borg C. Amigorena S. Vaccination of metastatic melanoma patients with autologous dendritic cell (DC) derived-exosomes: Results of thefirst phase I clinical trial J. Transl. Med. 2005 3 10 10.1186/1479-5876-3-10 15740633 PMC554765
97. Gandhi U.H. Cornell R.F. Lakshman A. Gahvari Z.J. McGehee E. Jagosky M.H. Gupta R. Varnado W. Fiala M.A. Chhabra S. Outcomes of patients with multiple myeloma refractory to CD38-targeted monoclonal antibody therapy Leukemia 2019 33 2266 2275 10.1038/s41375-019-0435-7 30858549 PMC6820050
98. Schwarzenbach H. Expression of MDR1/P-Glycoprotein, the Multidrug Resistance Protein MRP, and the Lung-Resistance Protein LRP in Multiple Myeloma Med Oncol. 2002 19 87 104 10.1385/MO:19:2:87 12180485
99. Pick M. Vainstein V. Goldschmidt N. Lavie D. Libster D. Gural A. Grisariu S. Avni B. Ben Yehuda D. Gatt M.E. Daratumumab resistance is frequent in advanced-stage multiple myeloma patients irrespective of CD38 expression and is related to dismal prognosis Eur. J. Haematol. 2018 100 494 501 10.1111/ejh.13046 29453884
100. Meads M.B. Hazlehurst L.A. Dalton W.S. The Bone Marrow Microenvironment as a Tumor Sanctuary and Contributor to Drug Resistance Clin. Cancer Res. 2008 14 2519 2526 10.1158/1078-0432.CCR-07-2223 18451212
101. Di Marzo L. Desantis V. Solimando A.G. Ruggieri S. Annese T. Nico B. Fumarulo R. Vacca A. Frassanito M.A. Microenvironment drug resistance in multiple myeloma: Emerging new players Oncotarget 2016 7 60698 60711 10.18632/oncotarget.10849 27474171 PMC5312413
102. Ribatti D. Nico B. Vacca A. Multiple myeloma as a model for the role of bone marrow niches in the control of angiogenesis Int. Rev. Cell Mol. Biol. 2015 314 259 282 25619720 10.1016/bs.ircmb.2014.10.004
103. Dimopoulos M.A. Moreau P. Terpos E. Mateos M.V. Zweegman S. Cook G. Delforge M. Hájek R. Schjesvold F. Cavo M. Multiple myeloma: EHA-ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up Ann. Oncol. 2021 32 309 322 10.1016/j.annonc.2020.11.014 33549387
104. Manasanch E.E. Orlowski R.Z. Proteasome inhibitors in cancer therapy Nat. Rev. Clin. Oncol. 2017 14 417 433 10.1038/nrclinonc.2016.206 28117417 PMC5828026
105. Nunes A.T. Annunziata C.M. Proteasome inhibitors: Structure and function Semin. Oncol. 2017 44 377 380 10.1053/j.seminoncol.2018.01.004 29935898 PMC6020165
106. Nefedova Y. l Landowski T.H. Dalton W.S. Bone marrow stromal-derived soluble factors and direct cell contact contribute to de novo drug resistance of myeloma cells by distinct mechanisms Leukemia 2003 17 1175 1182 10.1038/sj.leu.2402924 12764386
107. Wang J. Hendrix A. Hernot S. Lemaire M. De Bruyne E. van Valckenborgh E. Lahoutte T. De Wever O. Vanderkerken K. Menu E. Bone marrow stromal cell–derived exosomes as communicators in drug resistance in multiple myeloma cells Blood 2014 124 555 566 10.1182/blood-2014-03-562439 24928860
108. Xu H. Han H. Song S. Yi N. Qian C. Qiu Y. Zhou W. Hong Y. Zhuang W. Li Z. Exosome-Transmitted PSMA3 and PSMA3-AS1 Promote Proteasome Inhibitor Resistance in Multiple Myeloma Clin. Cancer Res. 2019 25 1923 1935 10.1158/1078-0432.CCR-18-2363 30610101
109. Yamamoto T. Nakayama J. Yamamoto Y. Kuroda M. Hattori Y. Ochiya T. SORT1/LAMP2-mediated Extracellular Vesicle Secretion and Cell Adhesion Are Linked to Lenalidomide Resistance in Multiple Myeloma Blood Adv. 2022 6 2480 2495 10.1182/bloodadvances.2021005772 34979567 PMC9043942
110. Mateos M.-V. Cavo M. Blade J. Dimopoulos M.A. Suzuki K. Jakubowiak A. Knop S. Doyen C. Lucio P. Nagy Z. Overall survival with daratumumab, bortezomib, melphalan, and prednisone in newly diagnosed multiple myeloma (ALCYONE): A randomised, open-label, phase 3 trial Lancet 2020 395 132 141 10.1016/S0140-6736(19)32956-3 31836199
111. Ashour R. Ri M. Aly S.S. Yoshida T. Tachita T. Kanamori T. Aoki S. Kinoshita S. Narita T. Totani H. Expression analysis of two SLAM family receptors, SLAMF2 and SLAMF7, in patients with multiple myeloma Int. J. Hematol. 2019 110 69 76 10.1007/s12185-019-02649-3 31115879
112. Horenstein A.L. Bracci C. Morandi F. Malavasi F. CD38 in Adenosinergic Pathways and Metabolic Re-programming in Human Multiple Myeloma Cells: In-tandem Insights from Basic Science to Therapy Front. Immunol. 2019 10 760 10.3389/fimmu.2019.00760 31068926 PMC6491463
113. Morandi F. Marimpietri D. Horenstein A.L. Bolzoni M. Toscani D. Costa F. Castella B. Faini A.C. Massaia M. Pistoia V. Microvesicles released from multiple myeloma cells are equipped with ectoenzymes belonging to canonical and non-canonical adenosinergic pathways and produce adenosine from ATP and NAD Oncoimmunology 2018 7 e1458809 10.1080/2162402X.2018.1458809 30221054 PMC6136872
114. Röllig C. Schmidt C. Bornhäuser M. Ehninger G. Schmitz M. Auffermann-Gretzinger S. Induction of Cellular Immune Responses in Patients with Stage-I Multiple Myeloma After Vaccination with Autologous Idiotype-pulsed Dendritic Cells J. Immunother. 2011 34 100 106 10.1097/CJI.0b013e3181facf48 21150718
115. Wolfers J. Lozier A. Raposo G. Regnault A. Théry C. Masurier C. Flament C. Pouzieux S. Faure F. Tursz T. Tumor-derived exosomes are a source of shared tumor rejection antigens for CTL cross-priming Nat. Med. 2001 7 297 303 10.1038/85438 11231627
116. Wang J. Cao Z. Wang P. Zhang X. Tang J. He Y. Huang Z. Mao X. Shi S. Kou X. Apoptotic Extracellular Vesicles Ameliorate Multiple Myeloma by Restoring Fas-Mediated Apoptosis ACS Nano 2021 15 14360 14372 10.1021/acsnano.1c03517 34506129
117. Caby M.-P. Lankar D. Vincendeau-Scherrer C. Raposo G. Bonnerot C. Exosomal-like vesicles are present in human blood plasma Int. Immunol. 2005 17 879 887 10.1093/intimm/dxh267 15908444
118. Palanisamy V. Sharma S. Deshpande A. Zhou H. Gimzewski J. Wong D.T. Nanostructural and Transcriptomic Analyses of Human Saliva Derived Exosomes PLoS ONE 2010 5 e8577 10.1371/journal.pone.0008577 20052414 PMC2797607
119. Paredes P.T. Esser J. Admyre C. Nord M. Rahman Q.K. Lukic A. Rådmark O. Grönneberg R. Grunewald J. Eklund A. Bronchoalveolar lavage fluid exosomes contribute to cytokine and leukotriene production in allergic asthma Allergy 2012 67 911 919 10.1111/j.1398-9995.2012.02835.x 22620679
120. Muraoka S. Lin W. Chen M. Hersh S.W. Emili A. Xia W. Ikezu T. Assessment of separation methods for extracellular vesicles from human and mouse brain tissues and human cerebrospinal fluids Methods 2020 177 35 49 10.1016/j.ymeth.2020.02.002 32035230 PMC7667497
121. Lin L.-Y. Yang L. Zeng Q. Wang L. Chen M.-L. Zhao Z.-H. Ye G.-D. Luo Q.-C. Lv P.-Y. Guo Q.-W. Tumor-originated exosomal lncUEGC1 as a circulating biomarker for early-stage gastric cancer Mol. Cancer 2018 17 84 10.1186/s12943-018-0834-9 29690888 PMC5978993
122. Logozzi M. De Milito A. Lugini L. Borghi M. Calabrò L. Spada M. Perdicchio M. Marino M.L. Federici C. Iessi E. High Levels of Exosomes Expressing CD63 and Caveolin-1 in Plasma of Melanoma Patients PLoS ONE 2009 4 e5219 10.1371/journal.pone.0005219 19381331 PMC2667632
123. Maisano D. Mimmi S. Dattilo V. Marino F. Gentile M. Vecchio E. Fiume G. Nisticò N. Aloisio A. de Santo M.P. A novel phage display based platform for exosome diversity characterization Nanoscale 2022 14 2998 3003 10.1039/D1NR06804K 35141731
124. Sedlarikova L. Bollova B. Radova L. Brozova L. Jarkovsky J. Almasi M. Penka M. Kuglík P. Sandecká V. Stork M. Circulating exosomal long noncoding RNA PRINS—First findings in monoclonal gammopathies Hematol. Oncol. 2018 36 786 791 10.1002/hon.2554 30144133 PMC6585732
125. Di Noto G. Chiarini M. Paolini L. Mazzoldi E.L. Giustini V. Radeghieri A. Caimi L. Ricotta D. Immunoglobulin Free Light Chains and GAGs Mediate Multiple Myeloma Extracellular Vesicles Uptake and Secondary NfκB Nuclear Translocation Front. Immunol. 2014 5 517 10.3389/fimmu.2014.00517 25386176 PMC4209816
126. Manier S. Liu C.-J. Avet-Loiseau H. Park J. Shi J. Campigotto F. Salem K.Z. Huynh D. Glavey S.V. Rivotto B. Prognostic role of circulating exosomal miRNAs in multiple myeloma Blood 2017 129 2429 2436 10.1182/blood-2016-09-742296 28213378 PMC5409448