MicroRNA Transfer Between Bone Marrow Adipose and Multiple Myeloma Cells

Bone-organ axes: bidirectional crosstalk

In addition to its recognized role in providing structural support, bone plays a crucial role in maintaining the functionality and balance of various organs by secreting specific cytokines (also known as osteokines). This reciprocal influence extends to these organs modulating bone homeostasis and development, although this aspect has yet to be systematically reviewed. This review aims to elucidate this bidirectional crosstalk, with a particular focus on the role of osteokines. Additionally, it presents a unique compilation of evidence highlighting the critical function of extracellular vesicles (EVs) within bone-organ axes for the first time. Moreover, it explores the implications of this crosstalk for designing and implementing bone-on-chips and assembloids, underscoring the importance of comprehending these interactions for advancing physiologically relevant in vitro models. Consequently, this review establishes a robust theoretical foundation for preventing, diagnosing, and treating diseases related to the bone-organ axis from the perspective of cytokines, EVs, hormones, and metabolites.

Drug Resistance: The Role of Exosomal miRNA in the Microenvironment of Hematopoietic Tumors

Extracellular vesicles (EVs), including exosomes, have an important role thanks to their ability to communicate and exchange information between tumor cells and the tumor microenvironment (TME), and have also been associated with communicating anti-cancer drug resistance (DR). The increase in proliferation of cancer cells alters oxygen levels, which causes hypoxia and results in a release of exosomes by the cancer cells. In this review, the results of studies examining the role of exosomal miRNA in DR, and their mechanism, are discussed in detail in hematological tumors: leukemia, lymphoma, and multiple myeloma. In conclusion, we underline the exosome's function as a possible drug delivery vehicle by understanding its cargo. Engineered exosomes can be used to be more specific for personalized therapy.

Identification of key genes and miRNA-mRNA regulatory networks associated with bone marrow immune microenvironment regulations in multiple myeloma by integrative bioinformatics analysis

The deregulation of microRNAs (miRNAs) and genes in the bone marrow microenvironment have been involved with the pathogenesis of multiple myeloma (MM). However, the exploration of miRNA-mRNA regulatory networks in MM remains lacking. We used GSE125363, GSE125361, GSE47552, GSE2658, GSE136324, GSE16558, and GSE13591 datasets for this bioinformatics study. We identified 156 downregulated and 13 upregulated differentially expressed miRNAs (DEmiRs) in MM. The DEmiRs are associated with the enrichment of pathways mainly involved with cancers, cellular signaling, and immune regulations. We identified 112 hub genes associated with five significant clusters in MM. Moreover, we identified 9 upregulated hub genes (such as IGF1, RPS28, UBA52, CDKN1A, and CDKN2A) and 52 downregulated hub genes (such as TP53, PCNA, BRCA1, CCNB1, and MSH2) in MM that is targeted by DEmiRs. The expression of DEmiRs targeted two hub genes (CDKN2A and TP53) are correlated with the survival prognosis of MM patients. Furthermore, the expression level of CDKN2A is correlated with immune signatures, including CD4+ Regulatory T cells, T cell exhaustion, MHC Class I, immune checkpoint genes, macrophages, neutrophils, and TH2 cells in the TME of MM. Finally, we revealed the consistently deregulated expression level of key gene CDKN2A and its co-regulatory DEmiRs, including hsa-mir-192, hsa-mir-10b, hsa-mir-492, and hsa-mir-24 in the independent cohorts of MM. Identifying key genes and miRNA-mRNA regulatory networks may provide new molecular insights into the tumor immune microenvironment in MM.

Role of Adipose Tissue Derived Exosomes in Metabolic Disease

Adipose tissues perform physiological functions such as energy storage and endocrine, whose dysfunction will lead to severe metabolic disorders. Accumulating evidences show that exosomes can meditate communications between different tissues by transporting nucleic acids, proteins and other biological factors. More importantly, exosomes secreted by adipose tissue function as critical contributing factors that elucidate specific mechanisms in metabolic disturbance such as obesity, adipose inflammation and diabetes etc. Adipose tissue is the major source of circulating exosomal miRNAs. miRNA secreted from adipose tissues not only altered in patients with metabolic disease, but also result in an increase in metabolic organ talk. Here we have reviewed the latest progress on the role of adipose tissue derived exosomes roles in metabolic disorders. Moreover, the current obstacles hindering exosome-based therapeutic strategies have also been discussed.

Circulating miRNAs as Auxiliary Diagnostic Biomarkers for Multiple Myeloma: A Systematic Review, Meta-Analysis, and Recommendations

Multiple myeloma (MM) is a hematologic malignancy characterized by aberrant expansion of monoclonal plasma cells with high mortality and severe complications due to the lack of early diagnosis and timely treatment. Circulating miRNAs have shown potential in the diagnosis of MM with inconsistent results, which remains to be fully assessed. Here we updated a meta-analysis with relative studies and essays published in English before Jan 31, 2021. After steps of screening, 32 studies from 11 articles that included a total of 627 MM patients and 314 healthy controls were collected. All data were analyzed by REVMAN 5.3 and Stata MP 16, and the quality of included literatures was estimated by Diagnostic Accuracy Study 2 (QUADAS-2). The pooled area under the curve (AUC) shown in summary receiver operating characteristic (SROC) analyses of circulating miRNAs was 0.87 (95%CI, 0.81–0.89), and the sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) were 0.79, 0.86, 5, 0.27, 22, respectively. Meta-regression and subgroup analysis exhibited that “miRNA cluster”, patient “detailed stage or Ig isotype” accounted for a considerable proportion of heterogeneity, revealing the importance of study design and patient inclusion in diagnostic trials; thus standardized recommendations were proposed for further studies. In addition, the performance of the circulating miRNAs included in MM prognosis and treatment response prediction was summarized, indicating that they could serve as valuable biomarkers, which would expand their clinical application greatly.

Adipose Tissue-Derived Extracellular Vesicles and the Tumor Microenvironment: Revisiting the Hallmarks of Cancer

Extracellular vesicles (EVs) are crucial elements that sustain the communication between tumor cells and their microenvironment, and have emerged as a widespread mechanism of tumor formation and metastasis. In obesity, the adipose tissue becomes hypertrophic and hyperplastic, triggering increased production of pro-inflammatory adipokines, such as tumor necrosis factor α, interleukin 6, interleukin 1, and leptin. Furthermore, obese adipose tissue undergoes dysregulation in the cargo content of the released EVs, resulting in an increased content of pro-inflammatory proteins, fatty acids, and oncogenic microRNAs. These alterations drive obesity-associated inflammatory responses both locally and systemically. After being ignored for a long time, adipose tissues have recently received considerable attention as a major player in tumor microenvironment-linked obesity and cancer. The role of adipose tissue in the establishment and progression of cancer is reinforced by its high plasticity and inflammatory content. Such a relationship may be established by direct contact between adipocytes and cancer cells within the microenvironment or systemically, via EV-mediated cell-to-cell communication. Here, we highlight cues evidencing the influence of adipose tissue-derived EVs on the hallmarks of cancer, which are critical for tumor malignancy.

Bone-Adipose Tissue Crosstalk: Role of Adipose Tissue Derived Extracellular Vesicles in Bone Diseases

Bone is a metabolically active organ that undergoes constant remodeling throughout life. A failure of this process leads to pathological destructive bone diseases such as osteoporosis, rheumatoid arthritis, and osteoarthritis. Studies of the interplay between adipose tissue and bone system, have revealed that adipose tissue disorders (e.g. obesity) strongly influence the development of bone diseases. Adipokines secreted by adipose tissue play important roles in the crosstalk between bone and adipose tissue. Recently, extracellular vesicles (EVs) have been identified as a novel method of communication between different organs and have attracted increased attention in the field of bone remodeling process. Adipokines carried by EVs are known to play pivotal roles in bone remodeling processes including osteogenesis and osteoclastogenesis. In this review, we highlighted the role of adipose tissue derived EVs (EVs-AT) in the context of bone remodeling events and focused on the characteristics of EVs-AT and their components in the regulation of bone diseases. Moreover, we introduced the intriguing therapeutic application of EVs-AT in different pathological destructive bone diseases and proposed future directions for research on EVs-AT in bone diseases.

An Analysis of Mechanisms for Cellular Uptake of miRNAs to Enhance Drug Delivery and Efficacy in Cancer Chemoresistance

Up until recently, it was believed that pharmaceutical drugs and their metabolites enter into the cell to gain access to their targets via simple diffusion across the hydrophobic lipid cellular membrane, at a rate which is based on their lipophilicity. An increasing amount of evidence indicates that the phospholipid bilayer-mediated drug diffusion is in fact negligible, and that drugs pass through cell membranes via proteinaceous membrane transporters or carriers which are normally used for the transportation of nutrients and intermediate metabolites. Drugs can be targeted to specific cells and tissues which express the relevant transporters, leading to the design of safe and efficacious treatments. Furthermore, transporter expression levels can be manipulated, systematically and in a high-throughput manner, allowing for considerable progress in determining which transporters are used by specific drugs. The ever-expanding field of miRNA therapeutics is not without its challenges, with the most notable one being the safe and effective delivery of the miRNA mimic/antagonist safely to the target cell cytoplasm for attaining the desired clinical outcome, particularly in miRNA-based cancer therapeutics, due to the poor efficiency of neo-vascular systems revolting around the tumour site, brought about by tumour-induced angiogenesis. This acquisition of resistance to several types of anticancer drugs can be as a result of an upregulation of efflux transporters expression, which eject drugs from cells, hence lowering drug efficacy, resulting in multidrug resistance. In this article, the latest available data on human microRNAs has been reviewed, together with the most recently described mechanisms for miRNA uptake in cells, for future therapeutic enhancements against cancer chemoresistance.

Bone Marrow Adipocytes: A Link between Obesity and Bone Cancer

Cancers that grow in the bone marrow are for most patients scary, painful, and incurable. These cancers are especially hard to treat due to the supportive microenvironment provided by the bone marrow niche in which they reside. New therapies designed to target tumor cells have extended the life expectancy for these patients, but better therapies are needed and new ideas for how to target these cancers are crucial. This need has led researchers to interrogate whether bone marrow adipocytes (BMAds), which increase in number and size during aging and in obesity, contribute to cancer initiation or progression within the bone marrow. Across the globe, the consensus in the field is a unified "yes". However, how to target these adipocytes or the factors they produce and how BMAds interact with different tumor cells are open research questions. Herein, we review this research field, with the goal of accelerating research in the network of laboratories working in this area and attracting bright scientists with new perspectives and ideas to the field in order to bring about better therapies for patients with bone cancers.

Long-chain polyunsaturated omega-3 fatty acids reduce multiple myeloma exosome-mediated suppression of NK cell cytotoxicity

BACKGROUND

Despite the advances in the treatment of multiple myeloma (MM), complete remission is usually challenging. The interactions between tumor and host cells, in which exosomes (EXs) play critical roles, have been shown to be among the major deteriorative tumor-promoting factors herein. Therefore, any endeavor to beneficially target these EX-mediated interactions could be of high importance.

OBJECTIVES

a) To investigate the effects of myeloma EXs on natural killer (NK) cell functions. b) To check whether treatment of myeloma cells with eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA), two polyunsaturated omega-3 fatty acids with known anti-cancer effects, can modify myeloma EXs in terms of their effects on natural killer functions.

METHODS

L363 cells were treated with either EPA or DHA or left untreated and the released EXs (designated as E-EX, D-EX and C-EX, respectively) were used to treat NK cells for functional studies.

RESULTS

Myeloma EXs (C-EXs) significantly reduced NK cytotoxicity against K562 cells (P ≤ 0.05), while the cytotoxicity suppression was significantly lower (P ≤ 0.05) in the (E-EX)- and (D-EX)-treated NK cells compared to the (C-EX)-treated cells. The expression of the activating NK receptor NKG2D and NK degranulation, after treatment with the EXs, were both altered following the same pattern. However, C-EXs could increase IFN-γ production in NK cells (P < 0.01), which was not significantly affected by EPA/DHA treatment. This indicates a dual effect of myeloma EXs on NK cells functions.

CONCLUSION

Our observations showed that myeloma EXs have both suppressive and stimulatory effects on different NK functions. Treatment of myeloma cells with EPA/DHA can reduce the suppressive effects of myeloma EXs while maintaining their stimulatory effects. These findings, together with the previous findings on the anti-cancer effects of EPA/DHA, provide stronger evidence for the repositioning of the currently existing EPA/DHA supplements to be used in the treatment of MM as an adjuvant treatment. EXs released from L363 (myeloma) cells in their steady state increase IFN-γ production of NK cells, while reduce their cytotoxicity against the K562 cell line (right blue trace). EXs from L363 cells pre-treated with either EPA or DHA are weaker stimulators of IFN-γ production. These EXs also increase NK cytotoxicity and NKG2D expression (left brown trace) compared to the EXs obtained from untreated L363 cells. Based on these findings, myeloma EXs have both suppressive and stimulatory effects on different NK functions depending on the properties of their cells of origin, which can be exploited in the treatment of myeloma.

The Roles of Bone Marrow-Resident Cells as a Microenvironment for Bone Metastasis

It has been appreciated that the cross talk between bone metastatic cancer cells and bone marrow microenvironment influence one another to worsen bone metastatic disease progression. Bone marrow contains various cell types, including (1) cells of mesenchymal origin (e.g., osteoblasts, osteocytes, and adipocytes), (2) cells of hematopoietic origin (e.g., osteoclast and immune cells), and (3) others (e.g., endothelial cells and nerves). The recent studies have enabled us to discover many important cancer-derived factors responsible for the development of bone metastasis. However, many critical questions regarding the roles of bone microenvironment in bone metastatic progression remain elusive. To answer these questions, a deeper understanding of the cross talk between bone metastatic cancer and bone marrow microenvironment is clearly warranted.

The emerging role of exosomes in multiple myeloma

Multiple myeloma (MM), one of the most prevalent hematological malignancies, accounts for approximately 10% of all blood cancers. In spite of the recent advancements in MM therapy, this malignancy of terminally differentiated plasma cells (PCs) continues to remain a hard-to-cure disease due to the emergence of drug resistance and frequent relapses. It is now well-established that the tumor-supportive involvement of the bone marrow microenvironment (BMM) including the cellular and non-cellular elements are the major causes behind treatment failures of MM as well as its main complications such as osteolytic bone loss. Exosomes (EXs) are membranous structures that carry signaling molecules and have recently received a great deal of attention as important mediators of inter-cellular communication in health and disease. EXs involve in the growth and drug resistance of many tumors via delivering their rich contents of bioactive molecules including miRNAs, growth factors, cytokines, signaling molecules, etc. With regard to MM, many studies have reported that EXs are among the main culprits playing key roles in the vicious network within the BMM of these patients. The main producers of EXs that largely contribute to MM pathogenesis are bone marrow stromal cells (BMSCs) as well as MM cells themselves. These cell types produce large amounts of EXs that affect a variety of target cells including natural killer (NK) cells, osteoclasts (OCs) and osteoblasts (OBs) to the advantage of tumor survival and progression. These EXs contain a different profile of proteins and miRNAs from that of EXs obtained from their counterparts in healthy individuals. MM patients exhibit distinguishable elevations in some of their contents such as miR-21, miR-146a, let-7b and miR-18a, while some molecules like miR-15a are markedly downregulated in EXs of MM patients compared to healthy individuals. These findings make EXs desirable biomarkers for early prediction of disease progression and drug resistance in the context of MM. On the other hand, due to the tumor-supportive role of EXs, targeting these structures in parallel to the conventional therapeutic regimens may be a promising approach to a successful anti-MM therapy. In the present work, an extensive review of the literature has been carried out to highlight the recent advances in the field.

Development of a 3D bone marrow adipose tissue model

Over the past twenty years, evidence has accumulated that biochemically and spatially defined networks of extracellular matrix, cellular components, and interactions dictate cellular differentiation, proliferation, and function in a variety of tissue and diseases. Modeling in vivo systems in vitro has been undeniably necessary, but when simplified 2D conditions rather than 3D in vitro models are used, the reliability and usefulness of the data derived from these models decreases. Thus, there is a pressing need to develop and validate reliable in vitro models to reproduce specific tissue-like structures and mimic functions and responses of cells in a more realistic manner for both drug screening/disease modeling and tissue regeneration applications. In adipose biology and cancer research, these models serve as physiologically relevant 3D platforms to bridge the divide between 2D cultures and in vivo models, bringing about more reliable and translationally useful data to accelerate benchtop to bedside research. Currently, no model has been developed for bone marrow adipose tissue (BMAT), a novel adipose depot that has previously been overlooked as "filler tissue" but has more recently been recognized as endocrine-signaling and systemically relevant. Herein we describe the development of the first 3D, BMAT model derived from either human or mouse bone marrow (BM) mesenchymal stromal cells (MSCs). We found that BMAT models can be stably cultured for at least 3 months in vitro, and that myeloma cells (5TGM1, OPM2 and MM1S cells) can be cultured on these for at least 2 weeks. Upon tumor cell co-culture, delipidation occurred in BMAT adipocytes, suggesting a bidirectional relationship between these two important cell types in the malignant BM niche. Overall, our studies suggest that 3D BMAT represents a "healthier," more realistic tissue model that may be useful for elucidating the effects of MAT on tumor cells, and tumor cells on MAT, to identify novel therapeutic targets. In addition, proteomic characterization as well as microarray data (expression of >22,000 genes) coupled with KEGG pathway analysis and gene set expression analysis (GSEA) supported our development of less-inflammatory 3D BMAT compared to 2D culture. In sum, we developed the first 3D, tissue-engineered bone marrow adipose tissue model, which is a versatile, novel model that can be used to study numerous diseases and biological processes involved with the bone marrow.

The expression and role of miR-181a in multiple myeloma

This study aims to investigate the role of miR-181a in multiple myeloma (MM). Fresh peripheral blood and bone marrows were collected. Expression of miR-181a, BCL-2 mRNA, and NOVA1 mRNA was detected by RT-qPCR. The correlation between miR-181a and clinical features of MM was further analyzed. miR-181a in serum and bone marrow mononuclear cells of MM patients were significantly higher. And, miR-181a level was significantly higher in MM Durie-Salmon stage III than that in stage I+II. miR-181a was positively correlated to Durie-Salmon staging, age, kidney injury, bone injury, β2-MG whereas negatively related to red blood cell, hemoglobin, and albumin. Additionally, BCL-2 and NOVA1 were predicted to be downstream targets of miR-181a. BCL-2 mRNA was significantly higher in the bone marrow mononuclear cells from MM patients. To sum up, the miR-181a expression is increased in peripheral blood and bone marrow of MM patients and is closely related to the clinical pathological indicators of MM.

Epigenetics of Skeletal Diseases

PURPOSE OF REVIEW

Epigenetic mechanisms modify gene activity in a stable manner without altering DNA sequence. They participate in the adaptation to the environment, as well as in the pathogenesis of common complex disorders. We provide an overview of the role of epigenetic mechanisms in bone biology and pathology.

RECENT FINDINGS

Extensive evidence supports the involvement of epigenetic mechanisms (DNA methylation, post-translational modifications of histone tails, and non-coding RNAs) in the differentiation of bone cells and mechanotransduction. A variety of epigenetic abnormalities have been described in patients with osteoporosis, osteoarthritis, and skeletal cancers, but their actual pathogenetic roles are still unclear. A few drugs targeting epigenetic marks have been approved for neoplastic disorders, and many more are being actively investigated. Advances in the field of epigenetics underscore the complex interactions between genetic and environmental factors as determinants of osteoporosis and other common disorders. Likewise, they help to explain the mechanisms by which prenatal and post-natal external factors, from nutrition to psychological stress, impact our body and influence the risk of later disease.

Molecular Interaction of Bone Marrow Adipose Tissue with Energy Metabolism

PURPOSE OF REVIEW

The last decade has seen a resurgence in the study of bone marrow adipose tissue (BMAT) across diverse fields such as metabolism, haematopoiesis, skeletal biology and cancer. Herein, we review the most recent developments of BMAT research in both humans and rodents, including the distinct nature of BMAT; the autocrine, paracrine and endocrine interactions between BMAT and various tissues, both in physiological and pathological scenarios; how these interactions might impact energy metabolism; and the most recent technological advances to quantify BMAT.

RECENT FINDINGS

Though still dwarfed by research into white and brown adipose tissues, BMAT is now recognised as endocrine organ and is attracting increasing attention from biomedical researchers around the globe.

SUMMARY

We are beginning to learn the importance of BMAT both within and beyond the bone, allowing us to better appreciate the role of BMAT in normal physiology and disease.

Reflections on Cancer in the Bone Marrow: Adverse Roles of Adipocytes

This review highlights the recent advances in our understanding of adipocyte contributions to carcinogenesis or cancer disease progression for cancers in the bone.

PURPOSE

In this review, we aim to describe bone marrow adipose tissue and discuss the soluble adipocyte-derived cytokines (adipokines) or endocrine factors, adipocyte-derived lipids, and the actual or putative juxtacrine signaling between bone marrow adipocytes and tumor cells in the bone marrow. This relationship likely affects tumor cell initiation, proliferation, metastasis, and/or drug resistance.

RECENT FINDINGS

Bone marrow adipose may affect tumor proliferation, drug resistance, or cancer-induced bone disease and hence may be a new target in the fight against cancer.

SUMMARY

Overall, evidence is mixed regarding the role of bone marrow adipose and adipocytes in cancer progression, and more research in this arena is necessary to determine how these bone marrow microenvironmental cells contribute to malignancies in the marrow to identify novel, potentially targetable pathways.