Chronic myelogenous leukaemia exosomes modulate bone marrow microenvironment through activation of epidermal growth factor receptor

Extracellular vesicles in hematological malignancies: EV-dence for reshaping the tumoral microenvironment

Following their discovery at the end of the 20th century, extracellular vesicles (EVs) ranging from 50-1,000 nm have proven to be paramount in the progression of many cancers, including hematological malignancies. EVs are a heterogeneous group of cell-derived membranous structures that include small EVs (commonly called exosomes) and large EVs (microparticles). They have been demonstrated to participate in multiple physiological and pathological processes by allowing exchange of biological material (including among others proteins, DNA and RNA) between cells. They are therefore a crucial way of intercellular communication. In this context, malignant cells can release these extracellular vesicles that can influence their microenvironment, induce the formation of a tumorigenic niche, and prepare and establish distant niches facilitating metastasis by significantly impacting the phenotypes of surrounding cells and turning them toward supportive roles. In addition, EVs are also able to manipulate the immune response and to establish an immunosuppressive microenvironment. This in turn allows for ideal conditions for heightened chemoresistance and increased disease burden. Here, we review the latest findings and reports studying the effects and therapeutic potential of extracellular vesicles in various hematological malignancies. The study of extracellular vesicles remains in its infancy; however, rapid advances in the analysis of these vesicles in the context of disease allow us to envision prospects to improve the detection and treatment of hematological malignancies.

Application of cell-derived exosomes in the hematological malignancies therapy

Exosomes are small membrane vesicles of endocytic origin that are produced by both tumor and normal cells and can be found in physiological fluids like plasma and cell culture supernatants. They include cytokines, growth factors, proteins, lipids, RNAs, and metabolites and are important intercellular communication controllers in several disorders. According to a vast amount of research, exosomes could support or inhibit tumor start and diffusion in a variety of solid and hematological malignancies by paracrine signaling. Exosomes are crucial therapeutic agents for a variety of illnesses, such as cancer and autoimmune diseases. This review discusses the most current and encouraging findings from in vitro and experimental in vivo research, as well as the scant number of ongoing clinical trials, with a focus on the impact of exosomes in the treatment of malignancies. Exosomes have great promise as carriers of medications, antagonists, genes, and other therapeutic materials that can be incorporated into their core in a variety of ways. Exosomes can also alter the metabolism of cancer cells, alter the activity of immunologic effectors, and alter non-coding RNAs, all of which can alter the tumor microenvironment and turn it from a pro-tumor to an anti-tumor milieu. This subject is covered in the current review, which also looks at how exosomes contribute to the onset and progression of hematological malignancies, as well as their importance in diagnosing and treating these conditions.

IL-18 and VEGF-A trigger type 2 innate lymphoid cell accumulation and pro-tumoral function in chronic myeloid leukemia

Chronic myeloid leukemia (CML) is a hematologic malignancy associated to an unregulated growth of myeloid cells in bone marrow (BM) and peripheral blood (PB), characterized by the BCR-ABL1 translocation. Given the known cytokine impairment in the leukemic niche of CML, we investigated the impact of this microenvironmental dysregulation on innate lymphoid cells (ILC), whose role in cancer has recently emerged. Three ILC subsets are identified based on transcriptional profiles and cytokine secretion. We observed that interleukin 18 (IL-18) and vascular endothelial growth factor A (VEGF-A) are increased in CML patients' sera and that ILC2 are enriched in CML PB and BM. We found that IL-18 drives ILC2 proliferation and that CML ILC2 highly express CXCR4 and CXCR7 BM-homing receptors, potentially explaining their enrichment in PB and BM, respectively. Next, we showed that ILC2 are hyper-activated through a tumor-derived VEGF-Adependent mechanism, which leads to higher IL-13 secretion. In response to IL-13, leukemic cells increase their clonogenic capacity. Finally, we discovered that the pro-tumoral axis involving VEGF-A, IL-18 and ILC2 was disrupted upon tyrosine kinase inhibitor treatment, normalizing the levels of all these players in CML patients responding to therapy. Overall, our study uncovers the involvement of ILC2 in CML progression, mediated by VEGF-A and IL-18.

Renal cancer secretome induces migration of mesenchymal stromal cells

BACKGROUND

Advanced renal cell carcinoma (RCC) is therapeutically challenging. RCC progression is facilitated by mesenchymal stem/stromal cells (MSCs) that exert remarkable tumor tropism. The specific mechanisms mediating MSCs' migration to RCC remain unknown. Here, we aimed to comprehensively analyze RCC secretome to identify MSCs attractants.

METHODS

Conditioned media (CM) were collected from five RCC-derived cell lines (Caki-1, 786-O, A498, KIJ265T and KIJ308T) and non-tumorous control cell line (RPTEC/TERT1) and analyzed using cytokine arrays targeting 274 cytokines in addition to global CM proteomics. MSCs were isolated from bone marrow of patients undergoing standard orthopedic surgeries. RCC CM and the selected recombinant cytokines were used to analyze their influence on MSCs migration and microarray-targeted gene expression. The expression of genes encoding cytokines was evaluated in 100 matched-paired control-RCC tumor samples.

RESULTS

When compared with normal cells, CM from advanced RCC cell lines (Caki-1 and KIJ265T) were the strongest stimulators of MSCs migration. Targeted analysis of 274 cytokines and global proteomics of RCC CM revealed decreased DPP4 and EGF, as well as increased AREG, FN1 and MMP1, with consistently altered gene expression in RCC cell lines and tumors. AREG and FN1 stimulated, while DPP4 attenuated MSCs migration. RCC CM induced MSCs' transcriptional reprogramming, stimulating the expression of CD44, PTX3 and RAB27B. RCC cells secreted hyaluronic acid (HA), a CD44 ligand mediating MSCs' homing to the kidney. AREG emerged as an upregulator of MSCs' transcription.

CONCLUSIONS

Advanced RCC cells secrete AREG, FN1 and HA to induce MSCs migration, while DPP4 loss prevents its inhibitory effect on MSCs homing. RCC secretome induces MSCs' transcriptional reprograming to facilitate their migration. The identified components of RCC secretome represent potential therapeutic targets.

The Bone Marrow Immune Microenvironment in CML: Treatment Responses, Treatment-Free Remission, and Therapeutic Vulnerabilities

PURPOSE OF REVIEW

Tyrosine kinase inhibitors (TKIs) are very successful for the treatment of chronic myeloid leukaemia (CML) but are not curative in most patients due to persistence of TKI-resistant leukaemia stem cells (LSCs). The bone marrow immune microenvironment (BME) provides protection to the LSC through multidimensional interactions, driving therapy resistance, and highlighting the need to circumvent these protective niches therapeutically. This review updates the evidence for interactions between CML cells and the immune microenvironment with a view to identifying targetable therapeutic vulnerabilities and describes what is known about the role of immune regulation in treatment-free remission (TFR).

RECENT FINDINGS

Intracellular signalling downstream of the chemotactic CXCL12-CXCR4 axis, responsible for disrupted homing in CML, has been elucidated in LSCs, highlighting novel therapeutic opportunities. In addition, LSCs expressing CXCL12-cleaving surface protein CD26 were highly correlated with CML burden, building on existing evidence. Newer findings implicate the adhesion molecule CD44 in TKI resistance, while JAK/STAT-mediated resistance to TKIs may occur downstream of extrinsic signalling in the BME. Exosomal BME-LSC cross-communication has also been explored. Finally, further detail on the phenotypes of natural killer (NK) cells putatively involved in maintaining successful TFR has been published, and NK-based immunotherapies are discussed. Recent studies highlight and build on our understanding of the BME in CML persistence and TKI resistance, pinpointing therapeutically vulnerable interactions. Repurposing existing drugs and/or the development of novel inhibitors targeting these relationships may help to overcome these issues in TKI-resistant CML and be used as adjuvant therapy for sustained TFR.

Exploring RAB11A Pathway to Hinder Chronic Myeloid Leukemia-Induced Angiogenesis In Vivo

Neoangiogenesis is generally correlated with poor prognosis, due to the promotion of cancer cell growth, invasion and metastasis. The progression of chronic myeloid leukemia (CML) is frequently associated with an increased vascular density in bone marrow. From a molecular point of view, the small GTP-binding protein Rab11a, involved in the endosomal slow recycling pathway, has been shown to play a crucial role for the neoangiogenic process at the bone marrow of CML patients, by controlling the secretion of exosomes by CML cells, and by regulating the recycling of vascular endothelial factor receptors. The angiogenic potential of exosomes secreted by the CML cell line K562 has been previously observed using the chorioallantoic membrane (CAM) model. Herein, gold nanoparticles (AuNPs) were functionalized with an anti-RAB11A oligonucleotide (AuNP@RAB11A) to downregulate RAB11A mRNA in K562 cell line which showed a 40% silencing of the mRNA after 6 h and 14% silencing of the protein after 12 h. Then, using the in vivo CAM model, these exosomes secreted by AuNP@RAB11A incubated K562 did not present the angiogenic potential of those secreted from untreated K562 cells. These results demonstrate the relevance of Rab11 for the neoangiogenesis mediated by tumor exosomes, whose deleterious effect may be counteracted via targeted silencing of these crucial genes; thus, decreasing the number of pro-tumoral exosomes at the tumor microenvironment.

Tumour‑derived exosomes and their emerging roles in leukaemia (Review)

Exosomes are small vesicles with a diameter of ~40-100 nm that are secreted by the majority of endogenous cells under normal and pathological conditions. They contain abundant proteins, lipids, microRNAs, and biomolecules such as signal transduction molecules, adhesion factors and cytoskeletal proteins, and play an important role in exchanging materials and transmitting information between cells. Recent studies have shown that exosomes are involved in the pathophysiology of leukaemia by affecting the bone marrow microenvironment, apoptosis, tumour angiogenesis, immune escape and chemotherapy resistance. Furthermore, exosomes are potential biomarkers and drug carriers for leukaemia, impacting the diagnosis and treatment of leukaemia. The present study describes the biogenesis and general characteristics of exosomes, and then highlight the emerging roles of exosomes in different types of leukaemia. Finally, the value of clinical application of exosomes as biomarkers and drug carriers is discussed with the aim to provide novel strategies for the treatment of leukaemia.

Digital PCR as a New Method for Minimal Residual Disease Monitoring and Treatment Free Remission Management in Chronic Myeloid Leukemia Patients: Is It Reliable?

The effective and sensitive monitoring of Minimal Residual Disease or Measurable Residual Disease (MRD) is a very important aspect in the management of patients affected by hematologic malignancies. The recent availability of new technologies has opened to the improvement of MRD monitoring. It is particularly relevant in patients affected by Chronic Myeloid Leukemia (CML). MRD monitoring is key in the management of CML patients thanks to the efficacy of TKIs therapy. Moreover, the policies of TKIs discontinuation aimed at treatment free remission are strongly based on the good selection of patients eligible for stopping TKIs therapy. The recently described application of digital PCR in CML patients monitoring seems to improve the accuracy and precision in the identification of optimal responders. The present review reports an overview on the application of digital PCR in the monitoring of MRD in CML and its impact on TKIs discontinuation trials and, consequently, on TFR success.

Hypothesis: can transfer of primary neoplasm-derived extracellular vesicles and mitochondria contribute to the development of donor cell-derived hematologic neoplasms after allogeneic hematopoietic cell transplantation?

Allogeneic hematopoietic cell transplantation (allo-HCT) is an essential treatment option for various neoplastic and non-neoplastic hematologic diseases. Although its efficacy is modest, a significant proportion of patients experience relapse, graft-versus-host disease, infection or impaired hematopoiesis. Among these, the most frequent cause of post-transplant mortality is relapse, whereas the development of de novo hematologic neoplasms from donor cells after allo-HCT occurs on some occasion as a rare complication. The mechanisms involved in the pathogenesis of the de novo hematologic neoplasms from donor cells are complex, and a multifactorial process contributes to the development of this complication. Recently, extracellular vesicles, particularly exosomes, and mitochondria have been shown to play crucial roles in intercellular communication through the transfer of specific constituents, such as deoxyribonucleic acids, ribonucleic acids, lipids, metabolites and cytosolic and cell-surface proteins. Here, I discuss the potential causative roles of these subcellular components in the development of de novo hematologic neoplasms from donor cells after allo-HCT, in addition to other etiologies.

Meta-Analytic Comparison of Global RNA Transcriptomes of Acute and Chronic Myeloid Leukemia Cells Reveals Novel Gene Candidates Governing Myeloid Malignancies

Simple Summary

Despite advances in the understanding of genetic risk factors and molecular mechanisms underlying acute myeloid leukemia (AML) and chronic myeloid leukemia (CML), clinical outcomes of current therapies in terms of disease relapse and mortality rate pose a great economic and social burden. To overcome this, the identification of new molecular prognostic biomarkers and pharmacological targets is crucial. Recent studies have suggested that AML and CML may share common pathogenic mechanisms and cellular substrates. To this end, in the present study, global transcriptome profiles of AML and CML at the molecular and cellular level were directly compared using a combination of meta-analysis and modern statistics, and novel candidate genes and specific biological processes associated with the pathogenesis of AML and CML were characterized. Our study significantly improves our current understanding of myeloid leukemia and will help develop new therapeutic targets and biomarkers for disease progression, management and treatment response.

Abstract

Background: Acute myeloid leukemia (AML) and chronic myeloid leukemia (CML) represent a group of hematological malignancies characterized by the pathogenic clonal expansion of leukemic myeloid cells. The diagnosis and clinical outcome of AML and CML are complicated by genetic heterogeneity of disease; therefore, the identification of novel molecular biomarkers and pharmacological targets is of paramount importance. Methods: RNA-seq-based transcriptome data from a total of five studies were extracted from NCBI GEO repository and subjected to an in-depth bioinformatics analysis to identify differentially expressed genes (DEGs) between AML and CML. A systemic literature survey and functional gene ontology (GO) enrichment analysis were performed for the top 100 DEGs to identify novel candidate genes and biological processes associated with AML and CML. Results: LINC01554, PTMAP12, LOC644936, RPS27AP20 and FAM133CP were identified as novel risk genes for AML and CML. GO enrichment analysis showed that DEGs were significantly associated with pre-RNA splicing, reactive oxygen species and glycoprotein metabolism, the cellular endomembrane system, neutrophil migration and antimicrobial immune response. Conclusions: Our study revealed novel biomarkers and specific biological processes associated with AML and CML. Further studies are required to evaluate their value as molecular targets for managing and treating the myeloid malignancies.

Emerging roles of extracellular vesicles in normal and malignant hematopoiesis

Hematopoietic stem cells, regulated by their microenvironment (or “niche”), sustain the production of mature blood and immune cells. Leukemia cells remodel the microenvironment to enhance their survival, which is accompanied by the loss of support for normal hematopoiesis in hematologic malignancies. Extracellular vesicles (EVs) mediate intercellular communication in physiological and pathological conditions, and deciphering their functions in cell-cell interactions in the ecosystem can highlight potential therapeutic targets. In this Review, we illustrate the utility of EVs derived from various cell types, focusing on the biological molecules they contain and the behavioral alterations they can induce in recipient cells. We also discuss the potential for clinical application in hematologic malignancies, including EV-based therapeutic regimens, drug delivery via EVs, and the use of EVs (or their cargoes) as biomarkers.

Extracellular Vesicles in Myeloid Neoplasms

Myeloid neoplasms arise from malignant primitive cells, which exhibit growth advantage within the bone marrow microenvironment (BMM). The interaction between these malignant cells and BMM cells is critical for the progression of these diseases. Extracellular vesicles (EVs) are lipid bound vesicles secreted into the extracellular space and involved in intercellular communication. Recent studies have described RNA and protein alterations in EVs isolated from myeloid neoplasm patients compared to healthy controls. The altered expression of various micro-RNAs is the best-described feature of EVs of these patients. Some of these micro-RNAs induce growth-related pathways such as AKT/mTOR and promote the acquisition of stem cell-like features by malignant cells. Another well-described characteristic of EVs in myeloid neoplasms is their ability to suppress healthy hematopoiesis either via direct effect on healthy CD34+ cells or via alteration of the differentiation of BMM cells. These results support a role of EVs in the pathogenesis of myeloid neoplasms. mainly through mediating the interaction between malignant and BMM cells, and warrant further study to better understand their biology. In this review, we describe the reported alterations of EV composition in myeloid neoplasms and the recent discoveries supporting their involvement in the development and progression of these diseases.

Regulation of Malignant Myeloid Leukemia by Mesenchymal Stem Cells

Bone marrow microenvironment (BMM) has been proven to have benefits for both normal hematopoietic stem cell niche and pathological leukemic stem cell niche. In fact, the pathological leukemia microenvironment reprograms bone marrow niche cells, especially mesenchymal stem cells for leukemia progression, chemoresistance and relapse. The growth and differentiation of MSCs are modulated by leukemia stem cells. Moreover, chromatin abnormality of mesenchymal stem cells is sufficient for leukemia initiation. Here, we summarize the detailed relationship between MSC and leukemia. MSCs can actively and passively regulate the progression of myelogenous leukemia through cell-to-cell contact, cytokine-receptor interaction, and exosome communication. These behaviors benefit LSCs proliferation and survival and inhibit physiological hematopoiesis. Finally, we describe the recent advances in therapy targeting MSC hoping to provide new perspectives and therapeutic strategies for leukemia.

Exosome-mediated remodeling of the tumor microenvironment: From local to distant intercellular communication

Extracellular vesicles (EVs) are membrane-enveloped nanoscale particles that carry various bioactive signaling molecules secreted by cells. Their biological roles depend on the original cell type from which they are derived and their inclusions. Exosomes, a class of EVs, are released by almost all eukaryotic cell types, including tumor cells. Tumor cell-derived exosomes mediate signal transduction between tumor cells and surrounding non-tumor cells. This intercellular communication actively contributes to the remodeling of the tumor microenvironment (TME) to enable tumor growth, invasion, and metastasis. This review summarizes the latest progress in the exploration of exosome-mediated cell-cell communication implicated in TME remodeling and underlying mechanisms. We focus on the role of cell-cell interactions mediated by tumor cell-derived exosomes in promoting invasion and metastasis, and their potential as a therapeutic intervention target against distant metastasis. We also discuss the clinical translational significance of tumor-derived exosomes for early diagnosis, efficacy and progression evaluations.

The Role of Exosomes in the Progression and Therapeutic Resistance of Hematological Malignancies

Exosomes are membrane limited structures which derive from cell membranes and cytoplasm. When released into extracellular space, they circulate through the extracellular fluid, including the peripheral blood and tissue fluid. Exosomes surface molecules mediate their targeting to specific recipient cells and deliver their contents to recipient cells by receptor-ligand interaction and/or phagocytosis and/or endocytosis or direct fusion with cell membrane. Exosomes contain many functional molecules, including nucleic acids (DNAs, mRNAs, non-coding RNAs), proteins (transcription factors, enzymes), and lipids which have biological activity. By passing these cargos, exosomes can transfer information between cells. In this way, exosomes are extensively involved in physiological and pathological processes, such as angiogenesis, matrix reprogramming, coagulation, tumor progression. In recent years, researcher have found that exosomes from malignant tumors can mediate information exchange between tumor cells or between tumor cells and non-tumor cells, thereby promoting tumor survival, progression, and resistance to therapy. In this review, we discuss the pro-tumor and anti-therapeutic effects of exosomes in hematological malignancies, hoping to contribute to the early conquest of hematological malignancy.

Acute lymphoblastic leukemia-derived extracellular vesicles affect quiescence of hematopoietic stem and progenitor cells

Patient-derived xenografted (PDX) models were generated through the transplantation of primary acute lymphoblastic leukemia (ALL) cells into immunodeficient NSG mice. We observed that ALL cells from mouse bone marrow (BM) produced extracellular vesicles (EVs) with specific expression of inducible heat shock protein HSP70, which is commonly activated in cancer cells. Taking advantage of this specific expression, we designed a strategy to generate fluorescent HSP70-labeled ALL EVs and monitor the impact of these EVs on endogenous murine BM cells ex vivo and in vivo. We discovered that hematopoietic stem and progenitor cells (HSPC) were mainly targeted by ALL EVs, affecting their quiescence and maintenance in the murine BM environment. Investigations revealed that ALL EVs were enriched in cholesterol and other metabolites that contribute to promote the mitochondrial function in targeted HSPC. Furthermore, using CD34⁺ cells isolated from cord blood, we confirmed that ALL EVs can modify quiescence of human HSPC. In conclusion, we have discovered a new oncogenic mechanism illustrating how EVs produced by proliferative ALL cells can target and compromise a healthy hematopoiesis system during leukemia development.

Chronic myeloid leukemia stem cells: targeting therapeutic implications

Chronic myeloid leukemia (CML) is a clonal myeloproliferative neoplasm driven by BCR-ABL1 oncoprotein, which plays a pivotal role in CML pathology, diagnosis, and treatment as confirmed by the success of tyrosine kinase inhibitor (TKI) therapy. Despite advances in the development of more potent tyrosine kinase inhibitors, some mechanisms particularly in terms of CML leukemic stem cell (CML LSC) lead to intrinsic or acquired therapy resistance, relapse, and disease progression. In fact, the maintenance CML LSCs in patients who are resistance to TKI therapy indicates the role of CML LSCs in resistance to therapy through survival mechanisms that are not completely dependent on BCR-ABL activity. Targeting therapeutic approaches aim to eradicate CML LSCs through characterization and targeting genetic alteration and molecular pathways involving in CML LSC survival in a favorable leukemic microenvironment and resistance to apoptosis, with the hope of providing a functional cure. In other words, it is possible to develop the combination therapy of TKs with drugs targeting genes or molecules more specifically, which is required for survival mechanisms of CML LSCs, while sparing normal HSCs for clinical benefits along with TKIs.

Shedding Light on Targeting Chronic Myeloid Leukemia Stem Cells

Chronic myeloid leukemia stem cells (CML LSCs) are a rare and quiescent population that are resistant to tyrosine kinase inhibitors (TKI). When TKI therapy is discontinued in CML patients in deep, sustained and apparently stable molecular remission, these cells in approximately half of the cases restart to grow, resuming the leukemic process. The elimination of these TKI resistant leukemic stem cells is therefore an essential step in increasing the percentage of those patients who can reach a successful long-term treatment free remission (TFR). The understanding of the biology of the LSCs and the identification of the differences, phenotypic and/or metabolic, that could eventually allow them to be distinguished from the normal hematopoietic stem cells (HSCs) are therefore important steps in designing strategies to target LSCs in a rather selective way, sparing the normal counterparts.

Exosomes and Brain Metastases: A Review on Their Role and Potential Applications

Brain metastases (BM) are a frequent complication in patients with advanced stages of cancer, associated with impairment of the neurological function, quality of life, prognosis, and survival. BM treatment consists of a combination of the available cancer therapies, such as surgery, radiotherapy, chemotherapy, immunotherapy and targeted therapies. Even so, cancer patients with BM are still linked to poor prognosis, with overall survival being reported as 12 months or less. Intercellular communication has a pivotal role in the development of metastases, therefore, it has been extensively studied not only to better understand the metastization process, but also to further develop new therapeutic strategies. Exosomes have emerged as key players in intercellular communication being potential therapeutic targets, drug delivery systems (DDS) or biomarkers. In this Review, we focus on the role of these extracellular vesicles (EVs) in BM formation and their promising application in the development of new BM therapeutic strategies.

Extracellular Vesicles and Hematopoietic Stem Cell Aging

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Exosomes: a new perspective in EGFR-mutated lung cancer

Exosomes are major contributors in cell to cell communication due to their ability to transfer biological material such as protein, RNA, DNA, and miRNA. Additionally, they play a role in tumor initiation, promotion, and progression, and recently, they have emerged as a potential source of information on tumor detection and may be useful as diagnostic, prognostic, and predictive tools. This review focuses on exosomes from lung cancer with a focus on EGFR mutations. Here, we outline the role of exosomes and their functional effect in carcinogenesis, tumor progression, and metastasis. Finally, we discuss the possibility of exosomes as novel biomarkers in early detection, diagnosis, assessment of prognosis, and prediction of therapeutic response in EGFR-mutated lung cancer.

The evolution of leukaemia from pre-leukaemic and leukaemic stem cells

Haematopoietic stem and progenitor cells (HSPCs) are defined as unspecialized cells that give rise to more differentiated cells. In a similar way, leukaemic stem and progenitor cells (LSPCs) are defined as unspecialized leukaemic cells, which can give rise to more differentiated cells. Leukaemic cells carry leukaemic mutations/variants and have clear differentiation abnormalities. Pre-leukaemic HSPCs (PreL-HSPCs) carry pre-leukaemic mutations/variants (pLMs) and are capable of producing mature functional cells, which will carry the same variants. Under the roof of LSPCs, one can find a broad range of cell types genetic and disease phenotypes. Present-day knowledge suggests that this phenotypic heterogeneity is the result of interactions between the cell of origin, the genetic background and the microenvironment background. The combination of these attributes will define the LSPC phenotype, frequency, differentiation capacity and evolutionary trajectory. Importantly, as LSPCs are leukaemia-initiating cells that sustain clinical remission and are the source of relapse, an improved understanding of LSPCs phenotype would offer better clinical opportunities for the treatment and hopefully prevention of human leukaemia. The current review will focus on LSPCs attributes in the context of human haematologic malignancies.

The "Vesicular Intelligence" Strategy of Blood Cancers

Blood cancers are a heterogeneous group of disorders including leukemia, multiple myeloma, and lymphoma. They may derive from the clonal evolution of the hemopoietic stem cell compartment or from the transformation of progenitors with immune potential. Extracellular vesicles (EVs) are membrane-bound nanovesicles which are released by cells into body fluids with a role in intercellular communication in physiology and pathology, including cancer. EV cargos are enriched in nucleic acids, proteins, and lipids, and these molecules can be delivered to target cells to influence their biological properties and modify surrounding or distant targets. In this review, we will describe the “smart strategy” on how blood cancer-derived EVs modulate tumor cell development and maintenance. Moreover, we will also depict the function of microenvironment-derived EVs in blood cancers and discuss how the interplay between tumor and microenvironment affects blood cancer cell growth and spreading, immune response, angiogenesis, thrombogenicity, and drug resistance. The potential of EVs as non-invasive biomarkers will be also discussed. Lastly, we discuss the clinical application viewpoint of EVs in blood cancers. Overall, blood cancers apply a ‘vesicular intelligence’ strategy to spread signals over their microenvironment, promoting the development and/or maintenance of the malignant clone.

Could Extracellular Vesicles Contribute to Generation or Awakening of "Sleepy" Metastatic Niches?

Pre-metastatic niches provide favorable conditions for tumor cells to disseminate, home to and grow in otherwise unfamiliar and distal microenvironments. Tumor-derived extracellular vesicles are now recognized as carriers of key messengers secreted by primary tumors, signals that induce the formation of pre-metastatic niches. Recent evidence suggests that tumor cells can disseminate from the very earliest stages of primary tumor development. However, once they reach distal sites, tumor cells can persist in a dormant state for long periods of time until their growth is reactivated and they produce metastatic lesions. In this new scenario, the question arises as to whether extracellular vesicles could influence the formation of these metastatic niches with dormant tumor cells? (here defined as "sleepy niches"). If so, what are the molecular mechanisms involved? In this perspective-review article, we discuss the possible influence of extracellular vesicles in early metastatic dissemination and whether they might play a role in tumor cell dormancy. In addition, we comment whether extracellular vesicle-mediated signals may be involved in tumor cell awakening, considering the possibility that extracellular vesicles might serve as biomarkers to detect early metastasis and/or minimal residual disease (MRD) monitoring.

Extracellular vesicles (EVs): What we know of the mesmerizing roles of these tiny vesicles in hematological malignancies?

Cancer is a complex disease in which a bidirectional collaboration between malignant cells and surrounding microenvironment creates an appropriate platform which ultimately facilitates the progression of the disease. The discovery of extracellular vesicles (EVs) was a turning point in the modern era of cancer biology, as their importance in human malignancies has set the stage to widen research interest in the field of cell-to-cell communication. The implication in short- and long-distance interaction via horizontally transfer of cellular components, ranging from non-coding RNAs to functional proteins, as well as stimulating target cells receptors by the means of ligands anchored on their membrane endows these "tiny vesicles with giant impacts" with incredible potential to re-educate normal tissues, and thus, to re-shape the surrounding niche. In this review, we highlight the pathogenic roles of EVs in human cancers, with an extensive focus on the recent advances in hematological malignancies.

Explainable drug sensitivity prediction through cancer pathway enrichment

Computational approaches to predict drug sensitivity can promote precision anticancer therapeutics. Generalizable and explainable models are of critical importance for translation to guide personalized treatment and are often overlooked in favor of prediction performance. Here, we propose PathDSP: a pathway-based model for drug sensitivity prediction that integrates chemical structure information with enrichment of cancer signaling pathways across drug-associated genes, gene expression, mutation and copy number variation data to predict drug response on the Genomics of Drug Sensitivity in Cancer dataset. Using a deep neural network, we outperform state-of-the-art deep learning models, while demonstrating good generalizability a separate dataset of the Cancer Cell Line Encyclopedia as well as provide explainable results, demonstrated through case studies that are in line with current knowledge. Additionally, our pathway-based model achieved a good performance when predicting unseen drugs and cells, with potential utility for drug development and for guiding individualized medicine.

Exosomes and Extracellular Vesicles in Myeloid Neoplasia: The Multiple and Complex Roles Played by These "Magic Bullets"

Simple Summary

Extracellular vesicles (EVs) are released by the majority of cell types and can be isolated from both cell cultures and body fluids. They are involved in cell-to-cell communication and may shuttle different messages (RNA, DNA, and proteins). These messages are known to influence the microenvironment of cells and their behavior. In recent years, some evidence about the involvement of EVs and exosomes, an EV subgroup, in immunomodulation, the transfer of disease markers, and the treatment of myeloid malignancies have been reported. Little is known about these vesicles in this particular setting of hematologic neoplasia; here, we summarize and critically review the available results, aiming to encourage further investigations.

Abstract

Extracellular vesicles (exosomes, in particular) are essential in multicellular organisms because they mediate cell-to-cell communication via the transfer of secreted molecules. They are able to shuttle different cargo, from nucleic acids to proteins. The role of exosomes has been widely investigated in solid tumors, which gave us surprising results about their potential involvement in pathogenesis and created an opening for liquid biopsies. Less is known about exosomes in oncohematology, particularly concerning the malignancies deriving from myeloid lineage. In this review, we aim to present an overview of immunomodulation and the microenvironment alteration mediated by exosomes released by malicious myeloid cells. Afterwards, we review the studies reporting the use of exosomes as disease biomarkers and their influence in response to treatment, together with the recent experiences that have focused on the use of exosomes as therapeutic tools. The further development of new technologies and the increased knowledge of biological (exosomes) and clinical (myeloid neoplasia) aspects are expected to change the future approaches to these malignancies.

Contribution of extracellular vesicles in normal hematopoiesis and hematological malignancies

Extracellular vesicles (EVs) are lipid bilayer-enclosed microparticles that have prominent roles in the intercellular crosstalk. EVs are secreted after fusion of endosomes with the plasma membrane (exosomes) or shed from the plasma membrane (microvesicles). These microparticles modulate bone marrow microenvironment and alter differentiation and expansion of normal hematopoietic cells. EVs originated from mesenchymal stromal cells have been shown to enhance expansion of myeloid-biased hematopoietic progenitor cells. In addition, megakaryocytic microparticles stimulate differentiation of hematopoietic stem and progenitor cells into mature megakaryocytes. The ability of EVs in induction of maturation and expansion of certain hematopoietic cells has implications in transfusion medicine and in targeted therapeutic modalities. Important prerequisites for these interventions are identification the specific targets of EVs, transferred biomolecules and molecular mechanisms underlying the fate decision in the target cells. EVs are also involved in the pathogenesis and progression of hematological malignancies including acute leukemia and multiples myeloma. In the current review, we provide a summary of studies which evaluated the significance of EVs in normal hematopoiesis and hematological malignancies.

Targeting Abnormal Hematopoietic Stem Cells in Chronic Myeloid Leukemia and Philadelphia Chromosome-Negative Classical Myeloproliferative Neoplasms

Myeloproliferative neoplasms (MPNs) are unique hematopoietic stem cell disorders sharing mutations that constitutively activate the signal-transduction pathways involved in haematopoiesis. They are characterized by stem cell-derived clonal myeloproliferation. The key MPNs comprise chronic myeloid leukemia (CML), polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). CML is defined by the presence of the Philadelphia (Ph) chromosome and BCR-ABL1 fusion gene. Despite effective cytoreductive agents and targeted therapy, complete CML/MPN stem cell eradication is rarely achieved. In this review article, we discuss the novel agents and combination therapy that can potentially abnormal hematopoietic stem cells in CML and MPNs and the CML/MPN stem cell-sustaining bone marrow microenvironment.

Molecular Testing in CML between Old and New Methods: Are We at a Turning Point?

Molecular monitoring of minimal residual disease (MRD) and BCR-ABL1 kinase domain (KD) mutation testing have a well consolidated role in the routine management of chronic myeloid leukemia (CML) patients, as they provide precious information for therapeutic decision-making. Molecular response levels are used to define whether a patient has an "optimal", "warning", or "failure" response to tyrosine kinase inhibitor (TKI) therapy. Mutation status may be useful to decide whether TKI therapy should be changed and which alternative TKI (or TKIs) are most likely to be effective. Real-time quantitative polymerase chain reaction (RQ-qPCR) and Sanger sequencing are currently the gold standard for molecular response monitoring and mutation testing, respectively. However, in recent years, novel technologies such as digital PCR (dPCR) and next-generation sequencing (NGS) have been evaluated. Here, we critically describe the main features of these old and novel technologies, provide an overview of the recently published studies assessing the potential clinical value of dPCR and NGS, and discuss how the state of the art might evolve in the next years.

Mechanisms of Action of EGFR Tyrosine Kinase Receptor Incorporated in Extracellular Vesicles

EGFR and some of the cognate ligands extensively traffic in extracellular vesicles (EVs) from different biogenesis pathways. EGFR belongs to a family of four homologous tyrosine kinase receptors (TKRs). This family are one of the major drivers of cancer and is involved in several of the most frequent malignancies such as non-small cell lung cancer, breast cancer, colorectal cancer and ovarian cancer. The carrier EVs exert crucial biological effects on recipient cells, impacting immunity, pre-metastatic niche preparation, angiogenesis, cancer cell stemness and horizontal oncogene transfer. While EV-mediated EGFR signalling is important to EGFR-driven cancers, little is known about the precise mechanisms by which TKRs incorporated in EVs play their biological role, their stoichiometry and associations to other proteins relevant to cancer pathology and EV biogenesis, and their means of incorporation in the target cell. In addition, it remains unclear whether different subtypes of EVs incorporate different complexes of TKRs with specific functions. A raft of high spatial and temporal resolution methods is emerging that could solve these and other questions regarding the activity of EGFR and its ligands in EVs. More importantly, methods are emerging to block or mitigate EV activity to suppress cancer progression and drug resistance. By highlighting key findings and areas that remain obscure at the intersection of EGFR signalling and EV action, we hope to cross-fertilise the two fields and speed up the application of novel techniques and paradigms to both.

Extracellular Vesicle Dissemination of Epidermal Growth Factor Receptor and Ligands and Its Role in Cancer Progression

Simple Summary

Overexpression of the transmembrane protein, epidermal growth factor receptor (EGFR), drives tumour progression in several cancers including breast, lung, glioblastoma and head and neck cancers. In recent years, it has been shown that tumour cells can transfer EGFR to other tumour cells and non-tumour cells using extracellular vesicles (EVs). EVs are nano-sized vesicles secreted by cells and contain protein, RNA and DNA. The function of EVs is to send messages between cells which occurs in both healthy and diseased states. In this review, we will discuss how the transfer of EGFR and EGFR ligands by EVs in cancer can promote metastases, the formation of new tumour blood vessels and decrease the anti-tumour activity of immune cells. We will also discuss how EGFR contained in EVs can be used as a non-invasive diagnostic marker of cancer, and finally, how EVs can be re-engineered to promote targeting to EGFR expressing tumours.

Abstract

The epidermal growth factor receptor (EGFR) pathway functions through the autocrine or paracrine activation of cellular EGFR by a number of transmembrane ligands. Amplified or mutant EGFR can lead to tumour formation due to increased cell proliferation, growth, migration and survival signals. These oncogenic effects were thought to be confined to aberrant cells hosting genetic alterations in EGFR. However, in the past decade, numerous studies identified that tumour cells could harness extracellular vesicles (EVs) to disseminate EGFR, mutant EGFR, phosphorylated EGFR and EGFR ligands to local and distant cells. This functions to impart a pro-tumourigenic phenotype in recipient cells. EVs play an essential role in intracellular communication, through receptor signalling or the release of their intra-vesicular content into recipient cells. This review will discuss the role of EVs delivering EGFR or EGFR ligands either to or from tumour cells and how this can promote metastases, pre-metastatic niche formation, osteoclastogenesis, angiogenesis and immune modulation in cancer. We will examine how circulating EVs positive for EGFR may be exploited as diagnostic, prognostic or therapeutic markers in cancers including breast, lung, glioblastoma, ovarian and prostate. Finally, we will explore recent breakthroughs in bio-engineering EVs with EGFR targeting abilities for targeted drug delivery.

Communication between stromal and hematopoietic stem cell by exosomes in normal and malignant bone marrow niche

Extracellular vesicles (EVs) have been regarded as important tools for cell-cell communication. They act as carriers for the transfer of various molecules such as genes, proteins and miRNA. EVs shift and transfer their ingredients to target cells in an active form. These particles have prominent roles in modulation of bone marrow (BM) niche; therefore they can regulate proliferation, differentiation, and other properties of hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs). This review discusses the different roles of EVs on BM niche; HPCs fate regulation and downstream effects of them on HSCs. Moreover, cellular and molecular mechanisms of BM microenvironment cross-talking are explained in healthy and malignant settings.

The regulatory role of exosomes in leukemia and their clinical significance

Recurrence is a primary cause of death in patients with leukemia. The interactions of tumor cells with the microenvironment and tumor stem cells hidden in bone marrow promote the recurrence and metastasis of leukemia to lymphoid tissue. Exosomes, membrane-coated nanovesicles secreted by living cells, perform biomaterial transfer and information exchange between cells. Exosomes contain various other biological components derived from parental cells, and they remotely regulate the function of target cells through body fluid flow. Recent studies revealed that exosomes participate in the development of leukemia and play important roles in its diagnosis and treatment by influencing cell proliferation and apoptosis, regulating bone marrow microenvironment, promoting angiogenesis, and inhibiting hematopoiesis. Exosomes are potential biomarkers and therapeutic targets for leukemia, and they can influence drug resistance. Leukemia-derived exosomes present leukemia-related antigens to target cells, promote the proliferation of leukemic cells, help these cells escape immunity, protect them from the cytotoxic effects of chemotherapeutics, and promote angiogenesis and tumor migration. Therefore, exosomes are closely related to the metastasis, treatment, and prognosis of leukemia, and they can be used to detect and monitor the progression of leukemia. This paper reviews the regulatory roles of exosomes in leukemia and their clinical significance.

Targeting epidermal growth factor-overexpressing triple-negative breast cancer by natural killer cells expressing a specific chimeric antigen receptor

OBJECTIVES

Traditional cancer therapy and regular immunotherapy are ineffective for treating triple-negative breast cancer (TNBC) patients. Recently, chimeric antigen receptor-engineered natural killer cells (CAR NK) have been applied to target several hormone receptors on different cancer cells to improve the efficacy of immunotherapy. Furthermore, epidermal growth factor receptor (EGFR) is a potential therapeutic target for TNBC. Here, we demonstrated that EGFR-specific CAR NK cells (EGFR-CAR NK cells) could be potentially used to treat patients with TNBC exhibiting enhanced EGFR expression.

MATERIALS AND METHODS

We investigated the cytotoxic effects of EGFR-CAR NK cells against TNBC cells in vitro and in vivo. The two types of EGFR-CAR NK cells were generated by transducing lentiviral vectors containing DNA sequences encoding the single-chain variable fragment (scFv) regions of the two anti-EGFR antibodies. The cytotoxic and anti-tumor effects of the two cell types were examined by performing cytokine release and cytotoxicity assays in vitro, and tumor growth assays in breast cancer cell line-derived xenograft (CLDX) and patient-derived xenograft (PDX) mouse models.

RESULTS

Both EGFR-CAR NK cell types were activated by TNBC cells exhibiting upregulated EGFR expression and specifically triggered the lysis of the TNBC cells in vitro. Furthermore, the two EGFR-CAR NK cell types inhibited CLDX and PDX tumors in mice.

CONCLUSIONS

This study suggested that treatment with EGFR-CAR NK cells could be a promising strategy for TNBC patients.

Deciphering the messages carried by extracellular vesicles in hematological malignancies

Extracellular vesicles (EVs) are nanosized membrane-bound particles released from all living cells examined thus far. EVs can transfer information in the form of proteins, nucleic acids, and lipids from donor cells to recipient cells. Here we summarize recent advances in understanding the role(s) EVs play in hematological malignancies (HM) and outline potential prognostic and diagnostic strategies using EVs. EVs have been shown to promote proliferation and angiogenesis, and alter the bone marrow microenvironment to favour the growth and survival of diverse HM. They also promote evasion of anti-cancer immune responses and increase multi-drug resistance. Using knowledge of EV biology, including HM-specific packaging of cargo, EV based diagnostics and therapeutic approaches show substantial clinical promise. However, while EVs may represent a new paradigm to solve many of the challenges in treating and/or diagnosing HM, much work is needed before they can be used clinically to improve patient outcomes.

The Impact of Matrix Metalloproteinase-9 on the Sequential Steps of the Metastatic Process

In industrialized countries, cancer is the second leading cause of death after cardiovascular disease. Most cancer patients die because of metastases, which consist of the self-transplantation of malignant cells in anatomical sites other than the one from where the tumor arose. Disseminated cancer cells retain the phenotypic features of the primary tumor, and display very poor differentiation indices and functional regulation. Upon arrival at the target organ, they replace preexisting, normal cells, thereby permanently compromising the patient's health; the metastasis can, in turn, metastasize. The spread of cancer cells implies the degradation of the extracellular matrix by a variety of enzymes, among which the matrix metalloproteinase (MMP)-9 is particularly effective. This article reviews the available published literature concerning the important role that MMP-9 has in the metastatic process. Additionally, information is provided on therapeutic approaches aimed at counteracting, or even preventing, the development of metastasis via the use of MMP-9 antagonists.

The Emerging Roles of Exosomes as EMT Regulators in Cancer

Epithelial–mesenchymal transition (EMT) causes epithelial cells to lose their polarity and adhesion property, and endows them with migratory and invasive properties to enable them to become mesenchymal stem cells. EMT occurs throughout embryonic development, during wound healing, and in various pathological processes, including tumor progression. Considerable research in the last few decades has revealed that EMT is invariably related to tumor aggressiveness and metastasis. Apart from the interactions between numerous intracellular signaling pathways known to regulate EMT, extracellular modulators in the tumor microenvironment also influence tumor cells to undergo EMT, with extracellular vesicles (EVs) receiving increasing attention as EMT inducers. EVs comprise exosomes and microvesicles that carry proteins, nucleic acids, lipids, and other small molecules to stimulate EMT in cells. Among EVs, exosomes have been investigated in many studies, and their role has been found to be significant with respect to regulating intercellular communications. In this review, we summarize recent studies on exosomes and their cargoes that induce cancer-associated EMT. Furthermore, we describe the possible applications of exosomes as promising therapeutic strategies.

Cell Stress Induced Stressome Release Including Damaged Membrane Vesicles and Extracellular HSP90 by Prostate Cancer Cells

Tumor cells exhibit therapeutic stress resistance-associated secretory phenotype involving extracellular vesicles (EVs) such as oncosomes and heat shock proteins (HSPs). Such a secretory phenotype occurs in response to cell stress and cancer therapeutics. HSPs are stress-responsive molecular chaperones promoting proper protein folding, while also being released from cells with EVs as well as a soluble form known as alarmins. We have here investigated the secretory phenotype of castration-resistant prostate cancer (CRPC) cells using proteome analysis. We have also examined the roles of the key co-chaperone CDC37 in the release of EV proteins including CD9 and epithelial-to-mesenchymal transition (EMT), a key event in tumor progression. EVs derived from CRPC cells promoted EMT in normal prostate epithelial cells. Some HSP family members and their potential receptor CD91/LRP1 were enriched at high levels in CRPC cell-derived EVs among over 700 other protein types found by mass spectrometry. The small EVs (30-200 nm in size) were released even in a non-heated condition from the prostate cancer cells, whereas the EMT-coupled release of EVs (200-500 nm) and damaged membrane vesicles with associated HSP90α was increased after heat shock stress (HSS). GAPDH and lactate dehydrogenase, a marker of membrane leakage/damage, were also found in conditioned media upon HSS. During this stress response, the intracellular chaperone CDC37 was transcriptionally induced by heat shock factor 1 (HSF1), which activated the CDC37 core promoter, containing an interspecies conserved heat shock element. In contrast, knockdown of CDC37 decreased EMT-coupled release of CD9-containing vesicles. Triple siRNA targeting CDC37, HSP90α, and HSP90β was required for efficient reduction of this chaperone trio and to reduce tumorigenicity of the CRPC cells in vivo. Taken together, we define "stressome" as cellular stress-induced all secretion products, including EVs (200-500 nm), membrane-damaged vesicles and remnants, and extracellular HSP90 and GAPDH. Our data also indicated that CDC37 is crucial for the release of vesicular proteins and tumor progression in prostate cancer.

Human BCR/ABL1 induces chronic myeloid leukemia-like disease in zebrafish

Chronic myeloid leukemia (CML) is induced by the BCR/ABL1 oncogene, which encodes a protein tyrosine kinase. We examined the effect of direct overexpression of the human p210 BCR/ABL1 oncoprotein in zebrafish. Humanized p210 BCR/ABL1 protein was detectable in Tg(hsp70: p210BCR/ABL1 ) transgenic zebrafish embryos and adult kidney marrow. Transgenic zebrafish developed CML, which could be induced via cells transplanted into recipients. The expression of human BCR/ABL1 promoted myeloid lineages in Tg(hsp70:p210BCR/ABL1) transgenic embryos. A total of 77 of 101 (76.24%) Tg(hsp70:p210BCR/ABL1) adult transgenic zebrafish (age 6 months-1 year) developed CML. CML in zebrafish showed a triphasic phenotype, similar to that in humans, involving a chronic phase predominantly characterized by neutrophils in various degrees of maturation, an accelerated phase with an increase in blasts and immature myeloid elements, and a blast phase with >90% blasts in both the peripheral blood and kidney marrow. Tyrosine kinase inhibitors, as the standard drug treatment for human CML, effectively reduced the expanded myeloid population in Tg(hsp70:p210BCR/ABL1) transgenic embryos. Moreover, we screened a library of 171 compounds and identified ten new drugs against BCR/ABL1 kinase-dependent or -independent pathways that could also reduce lcp1+ myeloid cell numbers in Tg(hsp70:p210BCR/ABL1) transgenic embryos. In summary, we generated the first humanized zebrafish CML model that recapitulates many characteristics of human CML. This novel in vivo model will help to elucidate the mechanisms of CML disease progression and allow high-throughput drug screening of possible treatments for this disease.

Exosomes as a storehouse of tissue remodeling proteases and mediators of cancer progression

Rapidly increasing scientific reports of exosomes and their biological effects have improved our understanding of their cellular sources and their cell-to-cell communication. These nano-sized vesicles act as potent carriers of regulatory bio-macromolecules and can induce regulatory functions by delivering them from its source to recipient cells. The details of their communication network are less understood. Recent studies have shown that apart from delivering its cargo to the cells, it can directly act on extracellular matrix (ECM) proteins and growth factors and can induce various remodeling events. More importantly, exosomes carry many surface-bound proteases, which can cleave different ECM proteins and carbohydrates and can shed cell surface receptors. These local extracellular events can modulate signaling cascades, which consequently influences the whole tissue and organ. This review aims to highlight the critical roles of exosomal proteases and their mechanistic insights within the cellular and extracellular environment.

Extracellular Vesicles and Cancer: A Focus on Metabolism, Cytokines, and Immunity

A better understanding of the mechanisms of cell communication between cancer cells and the tumor microenvironment is crucial to develop personalized therapies. It has been known for a while that cancer cells are metabolically distinct from other non-transformed cells. This metabolic phenotype is not peculiar to cancer cells but reflects the characteristics of the tumor microenvironment. Recently, it has been shown that extracellular vesicles are involved in the metabolic switch occurring in cancer and tumor-stroma cells. Moreover, in an immune system, the metabolic programs of different cell subsets are distinctly associated with their immunological function, and extracellular vesicles could be a key factor in the shift of cell fate modulating cancer immunity. Indeed, during tumor progression, tumor-associated immune cells and fibroblasts acquire a tumor-supportive and anti-inflammatory phenotype due to their interaction with tumor cells and several findings suggest a role of extracellular vesicles in this phenomenon. This review aims to collect all the available evidence so far obtained on the role of extracellular vesicles in the modulation of cell metabolism and immunity. Moreover, we discuss the possibility for extracellular vesicles of being involved in drug resistance mechanisms, cancer progression and metastasis by inducing immune-metabolic effects on surrounding cells.

Super-Enhancer-Associated Hub Genes In Chronic Myeloid Leukemia Identified Using Weighted Gene Co-Expression Network Analysis

Purpose

Super-enhancer (SE)-associated oncogenes extensively potentiate the uncontrolled proliferation capacity of cancer cells. In this study, we aimed to identify the SE-associated hub genes associated with the clinical characteristics of chronic myeloid leukemia (CML).

Methods

Eigengenes from CML clinical modules were determined using weighted gene co-expression network analysis (WGCNA). Overlapping genes between eigengenes and SE-associated genes were used to construct protein–protein interaction (PPI) networks and annotate for pathway enrichment analysis. Expression patterns of the top-ranked SE-associated hub genes were further determined in CML patients and healthy controls via real-time PCR. After treatment of K562 cells with the BRD4 inhibitor, JQ1, for 24 hrs, mRNA and protein levels of SE-associated hub genes were evaluated using real-time PCR and Western blotting, respectively. H3K27ac, H3K4me1 and BRD4 ChIP-seq signal peaks were used to predict and identify SEs visualized by the Integrative Genomics Viewer.

Results

The yellow module was significantly related to the status and pathological phase of CML. SE-associated hub candidate genes were mainly enriched in the cell cycle pathway. Based on the PPI networks of hub genes and the top rank of degree, five SE-associated genes were identified: specifically, BUB1, CENPO, KIF2C, ORC1, and RRM2. Elevated expression of these five genes was not only related to CML status and phase but also positively regulated by SE and suppressed by the BRD4 inhibitor, JQ1, in K562 cells. Strong signal peaks of H3K27ac, H3K4me1 and BRD4 ChIP-seq of the five genes were additionally observed close to the predicted SE regions.

Conclusion

This is the first study to characterize SE-associated genes linked to clinical characteristics of CML via weighted gene co-expression network analysis. Our results support a novel mechanism involving aberrant expression of hub SE-associated genes in CML patients and K562 cells, and these genes will be potential new therapeutic targets for human leukemia.

Liquid biopsies in myeloid malignancies

Hematologic malignancies are the most common type of cancer affecting children and young adults, and encompass diseases, such as leukemia, lymphoma, and myeloma, all of which impact blood associated tissues such as the bone marrow, lymphatic system, and blood cells. Clinical diagnostics of these malignancies relies heavily on the use of bone marrow samples, which is painful, debilitating, and not free from risks for leukemia patients. Liquid biopsies are based on minimally invasive assessment of markers in the blood (and other fluids) and have the potential to improve the efficacy of diagnostic/therapeutic strategies in leukemia patients, providing a useful tool for the real time molecular profiling of patients. The most promising noninvasive biomarkers are circulating tumor cells, circulating tumor DNA, microRNAs, and exosomes. Herein, we discuss the role of assessing these circulating biomarkers for the understanding of tumor progression and metastasis, tumor progression dynamics through treatment and for follow-up.

Targeting amphiregulin (AREG) derived from senescent stromal cells diminishes cancer resistance and averts programmed cell death 1 ligand (PD-L1)-mediated immunosuppression

Aging is characterized by a progressive loss of physiological integrity, while cancer represents one of the primary pathological factors that severely threaten human lifespan and healthspan. In clinical oncology, drug resistance limits the efficacy of most anticancer treatments, and identification of major mechanisms remains a key to solve this challenging issue. Here, we highlight the multifaceted senescence-associated secretory phenotype (SASP), which comprises numerous soluble factors including amphiregulin (AREG). Production of AREG is triggered by DNA damage to stromal cells, which passively enter senescence in the tumor microenvironment (TME), a process that remarkably enhances cancer malignancy including acquired resistance mediated by EGFR. Furthermore, paracrine AREG induces programmed cell death 1 ligand (PD-L1) expression in recipient cancer cells and creates an immunosuppressive TME via immune checkpoint activation against cytotoxic lymphocytes. Targeting AREG not only minimized chemoresistance of cancer cells, but also restored immunocompetency when combined with classical chemotherapy in humanized animals. Our study underscores the potential of in vivo SASP in driving the TME-mediated drug resistance and shaping an immunosuppressive niche, and provides the proof of principle of targeting major SASP factors to improve therapeutic outcome in cancer medicine, the success of which can substantially reduce aging-related morbidity and mortality.

MiR-33a Controls hMSCS Osteoblast Commitment Modulating the Yap/Taz Expression Through EGFR Signaling Regulation

Mesenchymal stromal cells (hMSCs) display a pleiotropic function in bone regeneration. The signaling involved in osteoblast commitment is still not completely understood, and that determines the failure of current therapies being used. In our recent studies, we identified two miRNAs as regulators of hMSCs osteoblast differentiation driving hypoxia signaling and cytoskeletal reorganization. Other signalings involved in this process are epithelial to mesenchymal transition (EMT) and epidermal growth factor receptor (EGFR) signalings through the regulation of Yes-associated protein (YAP)/PDZ-binding motif (TAZ) expression. In the current study, we investigated the role of miR-33a family as a (i) modulator of YAP/TAZ expression and (ii) a regulator of EGFR signaling during osteoblast commitments. Starting from the observation on hMSCs and primary osteoblast cell lines (Nh-Ost) in which EMT genes and miR-33a displayed a specific expression, we performed a gain and loss of function study with miR-33a-5p and 3p on hMSCs cells and Nh-Ost. After 24 h of transfections, we evaluated the modulation of EMT and osteoblast genes expression by qRT-PCR, Western blot, and Osteoimage assays. Through bioinformatic analysis, we identified YAP as the putative target of miR-33a-3p. Its role was investigated by gain and loss of function studies with miR-33a-3p on hMSCs; qRT-PCR and Western blot analyses were also carried out. Finally, the possible role of EGFR signaling in YAP/TAZ modulation by miR-33a-3p expression was evaluated. Human MSCs were treated with EGF-2 and EGFR inhibitor for different time points, and qRT-PCR and Western blot analyses were performed. The above-mentioned methods revealed a balance between miR-33a-5p and miR-33a-3p expression during hMSCs osteoblast differentiation. The human MSCs phenotype was maintained by miR-33a-5p, while the maintenance of the osteoblast phenotype in the Nh-Ost cell model was permitted by miR-33a-3p expression, which regulated YAP/TAZ through the modulation of EGFR signaling. The inhibition of EGFR blocked the effects of miR-33a-3p on YAP/TAZ modulation, favoring the maintenance of hMSCs in a committed phenotype. A new possible personalized therapeutic approach to bone regeneration was discussed, which might be mediated by customizing delivery of miR-33a in simultaneously targeting EGFR and YAP signaling with combined use of drugs.

Extracellular vesicles in urologic malignancies-Implementations for future cancer care

Extracellular vesicles (EVs), a heterogeneous group of vesicles differing in size and shape, cargo content and function, are membrane-bound and nano-sized vesicles that could be released by nearly all variations of cells. EVs have gained considerable attention in the past decades for their functions in modulating intercellular signalling and roles as potential pools for the novel diagnostic and prognostic biomarkers, as well as therapeutic targets in several cancers including urological neoplasms. In general, human and animal cells both can release distinct types of EVs, including exosomes, microvesicles, oncosomes and large oncosomes, and apoptotic bodies, while the content of EVs can be divided into proteins, lipids and nucleic acids. However, the lack of standard methods for isolation and detection platforms rein the widespread usage in clinical applications warranted furthermore investigations in the development of reliable, specific and sensitive isolation techniques. Whether and how the EVs work has become pertinent issues. With the aid of high-throughput proteomics or genomics methods, a fully understanding of contents contained in EVs from urogenital tumours, beyond all doubt, will improve our ability to identify the complex genomic alterations in the process of cancer and, in turn, contribute to detect potential therapeutic target and then provide personalization strategy for patient.

Feasibility of tumor‑derived exosome enrichment in the onco‑hematology leukemic model of chronic myeloid leukemia

Due to the discovery of their role in intra-cellular communications, exosomes, which carry information specific to the cell of origin, have garnered considerable attention in cancer research. Moreover, there is evidence to suggest the possibility of isolating different exosome sub-populations based on target antigens at the cell surface. Philadelphia chromosome-positive (Ph⁺) chronic myeloid leukemia (CML) is a clonal myeloproliferative neoplasia characterized by the break-point cluster region-proto-oncogene 1 tyrosine-protein kinase (BCR-ABL1) fusion-gene, derived from the t (9;22) translocation. Tyrosine kinase inhibitors (TKIs) target BCR-ABL1 protein and induce major or deep molecular responses in the majority of patients. Despite the fact that several studies have demonstrated the persistence of leukemic cells in the bone marrow niche, even following treatment, TKIs prolong patient survival time and facilitate treatment-free remission. These characteristics render CML a plausible model for investigating the feasibility of tumor-derived exosome fraction enrichment. In the present study, patients in the chronic phase (CP) of CML were treated with TKIs, and the quantification of the BCR-ABL1 exosomal transcript was performed using digital PCR (dPCR). The possibility of tumor-derived exosomes enrichment was confirmed, and for the first time, to the best of our knowledge, the detection of the BCR-ABL1 transcript highlighted the presence of active leukemic cells in patients with CP-CML. According to these findings, tumor-derived exosomes may be considered a novel tool for the identification of active leukemic cells, and for the assessment of innovative monitoring focused on the biological functions of exosomes in CML.