Breast cancer-derived microparticles display tissue selectivity in the transfer of resistance proteins to cells

Deciphering cellular and molecular mechanism of MUC13 mucin involved in cancer cell plasticity and drug resistance

There has been a surge of interest in recent years in understanding the intricate mechanisms underlying cancer progression and treatment resistance. One molecule that has recently emerged in these mechanisms is MUC13 mucin, a transmembrane glycoprotein. Researchers have begun to unravel the molecular complexity of MUC13 and its impact on cancer biology. Studies have shown that MUC13 overexpression can disrupt normal cellular polarity, leading to the acquisition of malignant traits. Furthermore, MUC13 has been associated with increased cancer plasticity, allowing cells to undergo epithelial-mesenchymal transition (EMT) and metastasize. Notably, MUC13 has also been implicated in the development of chemoresistance, rendering cancer cells less responsive to traditional treatment options. Understanding the precise role of MUC13 in cellular plasticity, and chemoresistance could pave the way for the development of targeted therapies to combat cancer progression and enhance treatment efficacy.

Lipid raft interacting galectin 8 regulates primary ciliogenesis

Primary cilium is a specialized sensory organelle that transmits environmental information into cells. Its length is tightly controlled by various mechanisms such as the frequency or the cargo size of the intraflagellar transport trains which deliver the building materials such as tubulin subunits essential for the growing cilia. Here, we show the sialoglycan interacting galectin 8 regulates the process of primary ciliogenesis. As the epithelia become polarized, there are more galectin 8 being apically secreted and these extracellular galectin 8 molecules apparently bind to a lipid raft enriched domain at the base of the primary cilia through interacting with lipid raft components, such as GD3 ganglioside and scaffold protein caveolin 1. Furthermore, the binding of galectin 8 at this critical region triggers rapid growth of primary cilia by perturbing the barrier function of the transition zone (TZ). Our study also demonstrates the functionality of this barrier depends on intact organization of lipid rafts at the cilia as genetically knockout of Cav1 and pharmacologically inhibition of lipid raft both phenocopy the effect of apical addition of recombinant galectin 8; that is, rapid elongation of primary cilia and redistribution of cilia proteins from TZ to the growing axoneme. Indeed, as cilia elongated, endogenous galectin 8, caveolin 1, and TZ component, TMEM231, also transited from the TZ to the growing axoneme. We also noted that the interaction between caveolin 1 and TMEM231 could be perturbed by exogenous galectin 8. Taken together, we proposed that galectin 8 promoted primary cilia elongation through impeding the barrier function of the TZ by interfering with the interaction between caveolin 1 and TMEM231.

Studying exogenous extracellular vesicle biodistribution by in vivo fluorescence microscopy

Extracellular vesicles (EVs) are lipid-bound vesicles released from cells that play a crucial role in many physiological processes and pathological mechanisms. As such, there is great interest in their biodistribution. One currently accessible technology to study their fate in vivo involves fluorescent labelling of exogenous EVs followed by whole-animal imaging. Although this is not a new technology, its translation from studying the fate of whole cells to subcellular EVs requires adaptation of the labelling techniques, excess dye removal and a refined experimental design. In this Review, we detail the methods and considerations for using fluorescence in vivo and ex vivo imaging to study the biodistribution of exogenous EVs and their roles in physiology and disease biology.

Extracellular Vesicles and Cancer Multidrug Resistance: Undesirable Intercellular Messengers?

Cancer multidrug resistance (MDR) is one of the main mechanisms contributing to therapy failure and mortality. Overexpression of drug transporters of the ABC family (ATP-binding cassette) is a major cause of MDR. Extracellular vesicles (EVs) are nanoparticles released by most cells of the organism involved in cell-cell communication. Their cargo mainly comprises, proteins, nucleic acids, and lipids, which are transferred from a donor cell to a target cell and lead to phenotypical changes. In this article, we review the scientific evidence addressing the regulation of ABC transporters by EV-mediated cell-cell communication. MDR transfer from drug-resistant to drug-sensitive cells has been identified in several tumor entities. This was attributed, in some cases, to the direct shuttle of transporter molecules or its coding mRNA between cells. Also, EV-mediated transport of regulatory proteins (e.g., transcription factors) and noncoding RNAs have been indicated to induce MDR. Conversely, the transfer of a drug-sensitive phenotype via EVs has also been reported. Additionally, interactions between non-tumor cells and the tumor cells with an impact on MDR are presented. Finally, we highlight uninvestigated aspects and possible approaches to exploiting this knowledge toward the identification of druggable processes and molecules and, ultimately, the development of novel therapeutic strategies.

Exosomes are involved in the intercellular transfer of rapamycin resistance in the breast cancer cells

Introduction

Resistance to chemotherapy and/or irradiation remains one of the key features of malignant tumors, which largely limits the efficiency of antitumor therapy. In this work, we studied the progression mechanism of breast cancer cell resistance to target drugs, including mTOR blockers, and in particular, we studied the exosome function in intercellular resistance transfer.

Methods

The cell viability was assessed by the MTT assay, exosomes were purified by successive centrifugations, immunoblotting was used to evaluate protein expression, AP-1 activity was analyzed using reporter assay.

Results

In experiments on the MCF-7 cell line (breast cancer) and the MCF-7/Rap subline that is resistant to rapamycin, the capability of resistant cell exosomes to trigger a similar rapamycin resistance in the parent MCF-7 cells was demonstrated. Exosome-induced resistance reproduces the changes revealed in MCF-7/Rap resistant cells, including the activation of ERK/AP-1 signaling, and it remains for a long time, for at least several months, after exosome withdrawal. We have shown that both the MCF-7 subline resistant to rapamycin and cells having exosome-triggered resistance demonstrate a stable decrease in the expression of DNMT3A, the key enzyme responsible for DNA methylation. Knockdown of DNMT3A in MCF-7 cells by siRNA leads to partial cell resistance to rapamycin; thus, the DNMT3A suppression is regarded as one of the necessary elements for the development of acquired rapamycin resistance.

Conclusion

We propose that DNA demethylation followed by increased expression of key genes may be one of the factors responsible for the progression and maintenance of the resistant cell phenotype that includes exosome-induced resistance.

Circulating biosignatures in multiple myeloma and their role in multidrug resistance

A major obstacle to chemotherapeutic success in cancer treatment is the development of drug resistance. This occurs when a tumour fails to reduce in size after treatment or when there is clinical relapse after an initial positive response to treatment. A unique and serious type of resistance is multidrug resistance (MDR). MDR causes the simultaneous cross resistance to unrelated drugs used in chemotherapy. MDR can be acquired through genetic alterations following drug exposure, or as discovered by us, through alternative pathways mediated by the transfer of functional MDR proteins and nucleic acids by extracellular vesicles (M Bebawy V Combes E Lee R Jaiswal J Gong A Bonhoure GE Grau, 23 9 1643 1649, 2009).Multiple myeloma is an incurable cancer of bone marrow plasma cells. Treatment involves high dose combination chemotherapy and patient response is unpredictable and variable due to the presence of multisite clonal tumour infiltrates. This clonal heterogeneity can contribute to the development of MDR. There is currently no approved clinical test for the minimally invasive testing of MDR in myeloma.Extracellular vesicles comprise a group of heterogeneous cell-derived membranous structures which include; exosomes, microparticles (microvesicles), migrasomes and apoptotic bodies. Extracellular vesicles serve an important role in cellular communication through the intercellular transfer of cellular protein, nucleic acid and lipid cargo. Of these, microparticles (MPs) originate from the cell plasma membrane and vary in size from 0.1-1um. We have previously shown that MPs confer MDR through the transfer of resistance proteins and nucleic acids. A test for the early detection of MDR would benefit clinical decision making, improve survival and support rational drug use. This review focuses on microparticles as novel clinical biomarkers for the detection of MDR in Myeloma and discusses their role in the therapeutic management of the disease.

Extracellular Vesicles Released from Cancer Cells Promote Tumorigenesis by Inducing Epithelial to Mesenchymal Transition via β-Catenin Signaling

Lung cancer is the leading cause of cancer-related deaths globally, in part due to a lack of early diagnostic tools and effective pharmacological interventions. Extracellular vesicles (EVs) are lipid-based membrane-bound particles released from all living cells in both physiological and pathological states. To understand the effects of lung-cancer-derived EVs on healthy cells, we isolated and characterized EVs derived from A549 lung adenocarcinoma cells and transferred them to healthy human bronchial epithelial cells (16HBe14o). We found that A549-derived EVs carry oncogenic proteins involved in the pathway of epithelial to mesenchymal transition (EMT) that are regulated by β-catenin. The exposure of 16HBe14o cells to A549-derived EVs resulted in a significant increase in cell proliferation, migration, and invasion via upregulating EMT markers such as E-Cadherin, Snail, and Vimentin and cell adhesion molecules such as CEACAM-5, ICAM-1, and VCAM-1, with concomitant downregulation of EpCAM. Our study suggests a role for cancer-cell-derived EVs to induce tumorigenesis in adjacent healthy cells by promoting EMT via β-catenin signaling.

The potential applications of microparticles in the diagnosis, treatment, and prognosis of lung cancer

Microparticles (MPs) are 100–1000 nm heterogeneous submicron membranous vesicles derived from various cell types that express surface proteins and antigenic profiles suggestive of their cellular origin. MPs contain a diverse array of bioactive chemicals and surface receptors, including lipids, nucleic acids, and proteins, which are essential for cell-to-cell communication. The tumour microenvironment (TME) is enriched with MPs that can directly affect tumour progression through their interactions with receptors. Liquid biopsy, a minimally invasive test, is a promising alternative to tissue biopsy for the early screening of lung cancer (LC). The diverse biomolecular information from MPs provides a number of potential biomarkers for LC risk assessment, early detection, diagnosis, prognosis, and surveillance. Remodelling the TME, which profoundly influences immunotherapy and clinical outcomes, is an emerging strategy to improve immunotherapy. Tumour-derived MPs can reverse drug resistance and are ideal candidates for the creation of innovative and effective cancer vaccines. This review described the biogenesis and components of MPs and further summarised their main isolation and quantification methods. More importantly, the review presented the clinical application of MPs as predictive biomarkers in cancer diagnosis and prognosis, their role as therapeutic drug carriers, particularly in anti-tumour drug resistance, and their utility as cancer vaccines. Finally, we discussed current challenges that could impede the clinical use of MPs and determined that further studies on the functional roles of MPs in LC are required.

Multidrug Resistance in Cancer: Understanding Molecular Mechanisms, Immunoprevention and Therapeutic Approaches

Cancer is one of the leading causes of death worldwide. Several treatments are available for cancer treatment, but many treatment methods are ineffective against multidrug-resistant cancer. Multidrug resistance (MDR) represents a major obstacle to effective therapeutic interventions against cancer. This review describes the known MDR mechanisms in cancer cells and discusses ongoing laboratory approaches and novel therapeutic strategies that aim to inhibit, circumvent, or reverse MDR development in various cancer types. In this review, we discuss both intrinsic and acquired drug resistance, in addition to highlighting hypoxia- and autophagy-mediated drug resistance mechanisms. Several factors, including individual genetic differences, such as mutations, altered epigenetics, enhanced drug efflux, cell death inhibition, and various other molecular and cellular mechanisms, are responsible for the development of resistance against anticancer agents. Drug resistance can also depend on cellular autophagic and hypoxic status. The expression of drug-resistant genes and the regulatory mechanisms that determine drug resistance are also discussed. Methods to circumvent MDR, including immunoprevention, the use of microparticles and nanomedicine might result in better strategies for fighting cancer.

Targeting the Ezrin Adaptor Protein Sensitizes Metastatic Breast Cancer Cells to Chemotherapy and Reduces Neoadjuvant Therapy-induced Metastasis

The main cause of cancer-associated deaths is the spread of cancer cells to distant organs. Despite its success in the primary tumor setting, modern chemotherapeutic strategies are rendered ineffective at treating metastatic disease, largely due to the development of resistance. The adaptor protein ezrin has been shown to promote cancer metastasis in multiple preclinical models and is associated with poor prognosis in several cancer types, including breast cancer. Ezrin promotes pro-survival signaling, particularly in disseminated cancer cells, to facilitate metastatic outgrowth. However, the role of ezrin in breast cancer chemoresistance is not fully known. In this study, we show that upregulating or downregulating ezrin expression modifies the sensitivity of breast cancer cells to doxorubicin and docetaxel treatment in vitro and is associated with changes in PI3K/Akt and NFκB pathway activation. In addition, we tested the effects of systemic treatment with a small-molecule ezrin inhibitor, NSC668394, on lung metastatic burden in vivo as a monotherapy, or in combination with anthracycline- or taxane-based chemotherapy treatment. We show that anti-ezrin treatment alone reduces metastatic burden and markedly sensitizes metastases to doxorubicin or docetaxel in neoadjuvant as well as neoadjuvant plus adjuvant treatment models. Taken together, our findings demonstrate the impact of anti-ezrin treatment in modulating response to chemotherapy in breast cancer cells as well as the efficacy of anti-ezrin treatment in combination with chemotherapy at reducing metastatic burden.

Significance

This work provides preclinical evidence for combining anti-ezrin treatment with chemotherapy as a novel strategy for effectively targeting metastasis, particularly in a neoadjuvant treatment setting.

Microparticles: biogenesis, characteristics and intervention therapy for cancers in preclinical and clinical research

Extracellular vesicles (EVs), spherical biological vesicles, mainly contain nucleic acids, proteins, lipids and metabolites for biological information transfer between cells. Microparticles (MPs), a subtype of EVs, directly emerge from plasma membranes, and have gained interest in recent years. Specific cell stimulation conditions, such as ultraviolet and X-rays irradiation, can induce the release of MPs, which are endowed with unique antitumor functionalities, either for therapeutic vaccines or as direct antitumor agents. Moreover, the size of MPs (100–1000 nm) and their spherical structures surrounded by a lipid bilayer membrane allow MPs to function as delivery vectors for bioactive antitumor compounds, with favorable phamacokinetic behavior, immunostimulatory activity and biological function, without inherent carrier-specific toxic side effects. In this review, the mechanisms underlying MP biogenesis, factors that influence MP production, properties of MP membranes, size, composition and isolation methods of MPs are discussed. Additionally, the applications and mechanisms of action of MPs, as well as the main hurdles for their applications in cancer management, are introduced.

Expression Patterns of Ezrin and AJAP1 and Clinical Significance in Breast Cancer

Ezrin and adherens junction-associated protein 1 (AJAP1) are structural proteins which are involved in numerous human malignancies. However, little is known about the relationship between them in breast cancer. This study was set out to investigate the relationship between them and to further explore the mechanism of AJAP1-mediating cytoskeleton in breast cancer progression. Ezrin and AJAP1 expressions were detected in 377 samples of breast cancer by immunohistochemistry, and different expression patterns between AJAP1 and Ezrin with clinicopathological parameters were analyzed. Besides, univariate and multivariate Cox models were used to evaluate their prognostic potential. Enzyme-linked immunosorbent assay, Western blot, qRT-PCR, and phalloidin staining of F-actin were used to explore the relationship and the mechanism between AJAP1 and Ezrin in cytoskeleton arrangement. 377 cases of breast cancer results showed that AJAP1 expression was negatively related with histological grade and lymph node involvement and could be an independent prognosis marker of breast cancer. AJAP1 expression tended to be higher in the Ezrin-negative expression case. Patients with AJAP1^negative and Ezrin^positive expression had a worse prognosis (p < 0.0001) and shorter DFS (p = 0.015). More importantly, AJAP1 depletion increased the cell ability of F-actin formation through promoting Ezrin expression. AJAP1 depletion might mediate breast cancer malignancy potential through promoting Ezrin expression and cytoskeleton formation.

Pioneer Role of Extracellular Vesicles as Modulators of Cancer Initiation in Progression, Drug Therapy, and Vaccine Prospects

Cancer is one of the leading diseases, causing deaths worldwide. Nearly 10 million deaths were reported in 2020 due to cancer alone. Several factors are involved in cancer progressions, such as lifestyle and genetic characteristics. According to a recent report, extracellular vesicles (EVs) are involved in cancer initiation, progression, and therapy failure. EVs can play a major role in intracellular communication, the maintenance of tissue homeostasis, and pathogenesis in several types of diseases. In a healthy person, EVs carry different cargoes, such as miRNA, lncRNA etc., to help other body functions. On the other hand, the same EV in a tumor microenvironment carries cargoes such as miRNA, lncRNA, etc., to initiate or help cancer progression at various stages. These stages may include the proliferation of cells and escape from apoptosis, angiogenesis, cell invasion, and metastasis, reprogramming energy metabolism, evasion of the immune response, and transfer of mutations. Tumor-derived EVs manipulate by altering normal functions of the body and affect the epigenetics of normal cells by limiting the genetic makeup through transferring mutations, histone modifications, etc. Tumor-derived EVs also pose therapy resistance through transferring drug efflux pumps and posing multiple drug resistances. Such EVs can also help as biomarkers for different cancer types and stages, which ultimately help with cancer diagnosis at early stages. In this review, we will shed light on EVs' role in performing normal functions of the body and their position in different hallmarks of cancer, in altering the genetics of a normal cell in a tumor microenvironment, and their role in therapy resistance, as well as the importance of EVs as diagnostic tools.

Treatment Failure in Acute Myeloid Leukemia: Focus on the Role of Extracellular Vesicles

Acute myeloblastic leukemia (AML) is one of the most common types of blood malignancies that results in an AML-associated high mortality rate each year. Several causes have been reported as prognostic factors for AML in children and adults, the most important of which are cytogenetic abnormalities and environmental risk factors. Following the discovery of numerous drugs for AML treatment, leukemic cells sought a way to escape from the cytotoxic effects of chemotherapy drugs, leading to treatment failure. Nowadays, comprehensive studies have looked at the role of extracellular vesicles (EVs) secreted by AML blasts and how the microenvironment of the tumor changes in favor of cancer progression and survival to discover the mechanisms of treatment failure to choose the well-advised treatment. Reports show that malignant cells secrete EVs that transmit messages to adjacent cells and the tumor's microenvironment. By secreting EVs, containing immune-inhibiting cytokines, AML cells inactivate the immune system against malignant cells, thus ensuring their survival. Also, increased secretion of EVs in various malignancies indicates an unfavorable prognostic factor and the possibility of drug resistance. In this study, we briefly reviewed the challenges of treating AML with a glance at the EVs' role in this process. It is hoped that with a deeper understanding of EVs, new therapies will be developed to eliminate the relapse of leukemic cells.

Roles of Microvesicles in Tumor Progression and Clinical Applications

Microvesicles are extracellular vesicles with diameter ranging from 100 to 1000 nm that are secreted by tumor cells or other cells in the tumor microenvironment. A growing number of studies demonstrate that tumor-derived microvesicles are involved in tumor initiation and progression, as well as drug resistance. In addition, tumor-derived microvesicles carry a variety of immunogenic molecules and inhibit tumor response to immunotherapy; therefore, they can be exploited for use in tumor vaccines. Moreover, because of their high stability, tumor-derived microvesicles extracted from body fluids can be used as biomarkers for cancer diagnosis or assessment of prognosis. Tumor-derived microvesicles can also be deployed to reverse drug resistance of tumor regenerative cells, or to deliver chemotherapeutic drugs and oncolytic adenovirus for the treatment of cancer patients. This review summarizes the general characteristics of tumor-derived microvesicles, focusing on their biological characteristics, their involvement in tumor progression, and their clinical applications.

Exosomes: A Forthcoming Era of Breast Cancer Therapeutics

Despite the recent advancements in therapeutics and personalized medicine, breast cancer remains one of the most lethal cancers among women. The prognostic and diagnostic aids mainly include assessment of tumor tissues with conventional methods towards better therapeutic strategies. However, current era of gene-based research may influence the treatment outcome particularly as an adjunct to diagnostics by exploring the role of non-invasive liquid biopsies or circulating markers. The characterization of tumor milieu for physiological fluids has been central to identifying the role of exosomes or small extracellular vesicles (sEVs). These exosomes provide necessary communication between tumor cells in the tumor microenvironment (TME). The manipulation of exosomes in TME may provide promising diagnostic/therapeutic strategies, particularly in triple-negative breast cancer patients. This review has described and highlighted the role of exosomes in breast carcinogenesis and how they could be used or targeted by recent immunotherapeutics to achieve promising intervention strategies.

Tailoring drug co-delivery nanosystem for mitigating U-87 stem cells drug resistance

Glioblastoma multiforme (GBM) is the most prevalent form of brain tumor, which generally has a poor prognosis. According to consensus, recurrence of the tumor and chemotherapy resistance acquisition are the two distinguishing features of GBM originated from glioblastoma stem cells (GSCs). To eliminate these obstacles inherent in GBM chemotherapy, targeting GSCs through a smart drug delivery system has come to the front position of GBM therapeutics. In this study, B19 aptamer (Apt)-conjugated polyamidoamine (PAMAM) G4C12 dendrimer nanoparticles (NPs), called Apt-NPs, were formulated for the co-delivery of paclitaxel (PTX) and temozolomide (TMZ) to U-87 stem cells. These drugs were loaded using a double emulsification solvent evaporation method. As a result, drug-loaded Apt-NPs significantly inhibited the tumor growth of U-87 stem cells, by the initiation of apoptosis via the downregulation of autophagic and multidrug resistance (MDR) genes. Additionally, by their downregulation by qPCR of CD133, CD44, SOX2, and the canonical Wnt/β-catenin pathway, cell proliferation has substantially decreased. Altogether, the results demonstrate that this intelligent drug co-delivery system is capable of effectively transferring PTX and TMZ to U-87 stem cells and without any toxic effect on Apt-NPs alone to U-87 stem cells. Furthermore, the designed dendrimer-based pharmaceutical system along with single-stranded B19 aptamer might be utilized as a new therapeutic strategy for the treatment of U-87 stem cells drug resistance in the GBM.

Biodistribution of extracellular vesicles following administration into animals: A systematic review

In recent years, attention has turned to examining the biodistribution of EVs in recipient animals to bridge between knowledge of EV function in vitro and in vivo. We undertook a systematic review of the literature to summarize the biodistribution of EVs following administration into animals. There were time-dependent changes in the biodistribution of small-EVs which were most abundant in the liver. Detection peaked in the liver and kidney in the first hour after administration, while distribution to the lungs and spleen peaked between 2-12 h. Large-EVs were most abundant in the lungs with localization peaking in the first hour following administration and decreased between 2-12 h. In contrast, large-EV localization to the liver increased as the levels in the lungs decreased. There was moderate to low localization of large-EVs to the kidneys while localization to the spleen was typically low. Regardless of the origin or size of the EVs or the recipient species into which the EVs were administered, the biodistribution of the EVs was largely to the liver, lungs, kidneys, and spleen. There was extreme variability in the methodology between studies and we recommend that guidelines should be developed to promote standardization where possible of future EV biodistribution studies.

Exploring interactions between extracellular vesicles and cells for innovative drug delivery system design

Extracellular vesicles (EVs) are submicron cell-secreted structures containing proteins, nucleic acids and lipids. EVs can functionally transfer these cargoes from one cell to another to modulate physiological and pathological processes. Due to their presumed biocompatibility and capacity to circumvent canonical delivery barriers encountered by synthetic drug delivery systems, EVs have attracted considerable interest as drug delivery vehicles. However, it is unclear which mechanisms and molecules orchestrate EV-mediated cargo delivery to recipient cells. Here, we review how EV properties have been exploited to improve the efficacy of small molecule drugs. Furthermore, we explore which EV surface molecules could be directly or indirectly involved in EV-mediated cargo transfer to recipient cells and discuss the cellular reporter systems with which such transfer can be studied. Finally, we elaborate on currently identified cellular processes involved in EV cargo delivery. Through these topics, we provide insights in critical effectors in the EV-cell interface which may be exploited in nature-inspired drug delivery strategies.

High-throughput proteomics of breast cancer interstitial fluid: identification of tumor subtype-specific serologically relevant biomarkers

Despite significant advancements in breast cancer (BC) research, clinicians lack robust serological protein markers for accurate diagnostics and tumor stratification. Tumor interstitial fluid (TIF) accumulates aberrantly externalized proteins within the local tumor space, which can potentially gain access to the circulatory system. As such, TIF may represent a valuable starting point for identifying relevant tumor-specific serological biomarkers. The aim of the study was to perform comprehensive proteomic profiling of TIF to identify proteins associated with BC tumor status and subtype. A liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis of 35 TIFs of three main subtypes: luminal (19), Her2 (4), and triple-negative (TNBC) (12) resulted in the identification of > 8800 proteins. Unsupervised hierarchical clustering segregated the TIF proteome into two major clusters, luminal and TNBC/Her2 subgroups. High-grade tumors enriched with tumor infiltrating lymphocytes (TILs) were also stratified from low-grade tumors. A consensus analysis approach, including differential abundance analysis, selection operator regression, and random forest returned a minimal set of 24 proteins associated with BC subtypes, receptor status, and TIL scoring. Among them, a panel of 10 proteins, AGR3, BCAM, CELSR1, MIEN1, NAT1, PIP4K2B, SEC23B, THTPA, TMEM51, and ULBP2, was found to stratify the tumor subtype-specific TIFs. In particular, upregulation of BCAM and CELSR1 differentiates luminal subtypes, while upregulation of MIEN1 differentiates Her2 subtypes. Immunohistochemistry analysis showed a direct correlation between protein abundance in TIFs and intratumor expression levels for all 10 proteins. Sensitivity and specificity were estimated for this protein panel by using an independent, comprehensive breast tumor proteome dataset. The results of this analysis strongly support our data, with eight of the proteins potentially representing biomarkers for stratification of BC subtypes. Five of the most representative proteomics databases currently available were also used to estimate the potential for these selected proteins to serve as putative serological markers.

Extracellular Vesicles in Chemoresistance

Chemotherapy represents the current mainstay therapeutic approach for most types of cancer. Despite the development of targeted chemotherapeutic strategies, the efficacy of anti-cancer drugs is severely limited by the development of drug resistance. Multidrug resistance (MDR) consists of the simultaneous resistance to various unrelated cytotoxic drugs and is one of the main causes of anticancer treatment failure. One of the principal mechanisms by which cancer cells become MDR involves the overexpression of ATP Binding Cassette (ABC) transporters, such as P-glycoprotein (P-gp), mediating the active efflux of cytotoxic molecules from the cytoplasm. Extracellular vesicles (EVs) are submicron lipid-enclosed vesicles that are released by all cells and which play a fundamental role in intercellular communication in physiological and pathological contexts. EVs have fundamental function at each step of cancer development and progression. They mediate the transmission of MDR through the transfer of vesicle cargo including functional ABC transporters as well as nucleic acids, proteins and lipids. Furthermore, EVs mediate MDR by sequestering anticancer drugs and stimulate cancer cell migration and invasion. EVs also mediate the communication with the tumour microenvironment and the immune system, resulting in increased angiogenesis, metastasis and immune evasion. All these actions contribute directly and indirectly to the development of chemoresistance and treatment failure. In this chapter, we describe the many roles EVs play in the acquisition and spread of chemoresistance in cancer. We also discuss possible uses of EVs as pharmacological targets to overcome EV-mediated drug resistance and the potential that the analysis of tumour-derived EVs offers as chemoresistance biomarkers.

Flow Cytometry Analysis of Circulating Extracellular Vesicle Subtypes from Fresh Peripheral Blood Samples

Extracellular vesicles (EVs) are released by shedding during different physiological processes and are increasingly thought to be new potential biomarkers. However, the impact of pre-analytical processing phases on the final measurement is not predictable and for this reason, the translation of basic research into clinical practice has been precluded. Here we have optimized a simple procedure in combination with polychromatic flow cytometry (PFC), to identify, classify, enumerate, and separate circulating EVs from different cell origins. This protocol takes advantage of a lipophilic cationic dye (LCD) able to probe EVs. Moreover, the application of the newly optimized PFC protocol here described allowed the obtainment of repeatable EVs counts. The translation of this PFC protocol to fluorescence-activated cell sorting allowed us to separate EVs from fresh peripheral blood samples. Sorted EVs preparations resulted particularly suitable for proteomic analyses, which we applied to study their protein cargo. Here we show that LCD staining allowed PFC detection and sorting of EVs from fresh body fluids, avoiding pre-analytical steps of enrichment that could impact final results. Therefore, LCD staining is an essential step towards the assessment of EVs clinical significance.

Novel Intrinsic Mechanisms of Active Drug Extrusion at the Blood-Brain Barrier: Potential Targets for Enhancing Drug Delivery to the Brain?

The blood-brain barrier (BBB) limits the pharmacotherapy of several brain disorders. In addition to the structural and metabolic characteristics of the BBB, the ATP-driven, drug efflux transporter P-glycoprotein (Pgp) is a selective gatekeeper of the BBB; thus, it is a primary hindrance to drug delivery into the brain. Here, we review the complex regulation of Pgp expression and functional activity at the BBB with an emphasis on recent studies from our laboratory. In addition to traditional processes such as transcriptional regulation and posttranscriptional or posttranslational modification of Pgp expression and functionality, novel mechanisms such as intra- and intercellular Pgp trafficking and intracellular Pgp-mediated lysosomal sequestration in BBB endothelial cells with subsequent disposal by blood neutrophils are discussed. These intrinsic mechanisms of active drug extrusion at the BBB are potential therapeutic targets that could be used to modulate P-glycoprotein activity in the treatment of brain diseases and enhance drug delivery to the brain.

Breast Cancer-Derived Microparticles Reduce Cancer Cell Adhesion, an Effect Augmented by Chemotherapy

Tumor cell heterogeneity is primarily dictated by mutational changes, sometimes leading to clones that undergo a metastatic switch. However, little is known about tumor heterogeneity following chemotherapy perturbation. Here we studied the possible involvement of tumor-derived extracellular vesicles, often referred to as tumor-derived microparticles (TMPs), as mediators of the metastatic switch in the tumor microenvironment by hindering cell adhesion properties. Specifically, we show that highly metastatic or chemotherapy-treated breast cancer cells shed an increased number of TMPs compared to their respective controls. We found that these TMPs substantially reduce cell adhesion and disrupt actin filament structure, therefore increasing their biomechanical force pace, further implicating tumor cell dissemination as part of the metastatic cascade. Our results demonstrate that these pro-metastatic effects are mediated in part by CD44 which is highly expressed in TMPs obtained from highly metastatic cells or cells exposed to chemotherapy when compared to cells with low metastatic potential. Consequently, when we inhibited CD44 expression on TMPs by a pharmacological or a genetic approach, increased tumor cell adhesion and re-organized actin filament structure were observed. We also demonstrated that breast cancer patients treated with paclitaxel chemotherapy exhibited increased CD44-expressing TMPs. Overall, our study provides further insights into the role of TMPs in promoting metastasis, an effect which is augmented when tumor cells are exposed to chemotherapy.

Selectively-Packaged Proteins in Breast Cancer Extracellular Vesicles Involved in Metastasis

Cancer-derived extracellular vesicles are known to play a role in the progression of the disease. In this rapidly-growing field, there are many reports of phenotypic changes in cells following exposure to cancer-derived extracellular vesicles. This study examines the protein contents of vesicles derived from three well-known breast cancer cell lines, MCF-7, MDA-MB-231 and T47D, using peptide-centric LC-MS/MS and cytokine multiplex immunoassay analysis to understand the molecular basis of these changes. Through these techniques a large number of proteins within these vesicles were identified. A large proportion of these proteins are known to be important in cancer formation and progression and associated with cancer signaling, angiogenesis, metastasis and invasion and immune regulation. This highlights the importance of extracellular vesicles (EVs) in cancer communications and shows some of the mechanisms the vesicles use to assist in cancer progression.

Recent Advances in Targeting of Breast Cancer Stem Cells Based on Biological Concepts and Drug Delivery System Modification

Breast cancer with various biological diversity known as the common reason of death in the world and despite progress in novel therapeutic approaches, it faced with failure and recurrence in general. Recent clinical and preclinical statistics support cancer stem cells (CSCs) hypothesis and its similarities with normal stem cells. Evaluation of related paper conclude in significance finding in the further characterization of CSCs biology such as surface biomarkers, microenvironment regulatory molecules, cell signaling pathways, cell to cell transition and drug efflux pumps to overcome multidrug resistance and effective therapy. Emerging novel data indicate biological concepts in the base of unsuccessful treatment. A powerful understanding of the cell signaling pathways in cancer and CSCs topics can be led us to define and control treatment problems in cancer. More recently nano medicine based on drug delivery system modification and new implications on combinatorial therapy have been used to treat breast cancer effectively. The aim of this review is focus on CSCs as a potential target of cancer therapy, to overcome the limitation and problems of current therapeutic strategies in cancer.

The Role of Extracellular Vesicles in the Hallmarks of Cancer and Drug Resistance

Extracellular vesicles (EVs) mediate intercellular signaling and communication, allowing the intercellular exchange of proteins, lipids, and genetic material. Their recognized role in the maintenance of the physiological balance and homeostasis seems to be severely disturbed throughout the carcinogenesis process. Indeed, the modus operandi of cancer implies the highjack of the EV signaling network to support tumor progression in many (if not all) human tumor malignancies. We have reviewed the current evidence for the role of EVs in affecting cancer hallmark traits by: (i) promoting cell proliferation and escape from apoptosis, (ii) sustaining angiogenesis, (iii) contributing to cancer cell invasion and metastasis, (iv) reprogramming energy metabolism, (v) transferring mutations, and (vi) modulating the tumor microenvironment (TME) by evading immune response and promoting inflammation. Special emphasis was given to the role of EVs in the transfer of drug resistant traits and to the EV cargo responsible for this transfer, both between cancer cells or between the microenvironment and tumor cells. Finally, we reviewed evidence for the increased release of EVs by drug resistant cells. A timely and comprehensive understanding of how tumor EVs facilitate tumor initiation, progression, metastasis and drug resistance is instrumental for the development of innovative EV-based therapeutic approaches for cancer.

Nutritional Exchanges Within Tumor Microenvironment: Impact for Cancer Aggressiveness

Neoplastic tissues are composed not only by tumor cells but also by several non-transformed stromal cells, such as cancer-associated fibroblasts, endothelial and immune cells, that actively participate to tumor progression. Starting from the very beginning of carcinogenesis, tumor cells, through the release of paracrine soluble factors and vesicles, i.e., exosomes, modify the behavior of the neighboring cells, so that they can give efficient support for cancer cell proliferation and spreading. A mandatory role in tumor progression has been recently acknowledged to metabolic deregulation. Beside undergoing a metabolic reprogramming coherent to their high proliferation rate, tumor cells also rewire the metabolic assets of their stromal cells, educating them to serve as nutrient donors. Hence, an alteration in the composition and in the flow rate of many nutrients within tumor microenvironment has been associated with malignancy progression. This review is focused on metabolic remodeling of the different cell populations within tumor microenvironment, dealing with reciprocal re-education through the symbiotic sharing of metabolites, behaving both as nutrients and as transcriptional regulators, describing their impact on tumor growth and metastasis.

A liquid biopsy to detect multidrug resistance and disease burden in multiple myeloma

Multiple myeloma is an incurable cancer of bone marrow plasma cells, with a 5-year survival rate of 43%. Its incidence has increased by 126% since 1990. Treatment typically involves high-dose combination chemotherapy, but therapeutic response and patient survival are unpredictable and highly variable—attributed largely to the development of multidrug resistance (MDR). MDR is the simultaneous cross-resistance to a range of unrelated chemotherapeutic agents and is associated with poor prognosis and survival. Currently, no clinical procedures allow for a direct, continuous monitoring of MDR. We identified circulating large extracellular vesicles (specifically microparticles (MPs)) that can be used to monitor disease burden, disease progression and development of MDR in myeloma. These MPs differ phenotypically in the expression of four protein biomarkers: a plasma-cell marker (CD138), the MDR protein, P-glycoprotein (P-gp), the stem-cell marker (CD34); and phosphatidylserine (PS), an MP marker and mediator of cancer spread. Elevated levels of P-gp⁺ and PS⁺ MPs correlate with disease progression and treatment unresponsiveness. Furthermore, P-gp, PS and CD34 are predominantly expressed in CD138⁻ MPs in advanced disease. In particular, a dual-positive (CD138⁻P-gp⁺CD34⁺) population is elevated in aggressive/unresponsive disease. Our test provides a personalised liquid biopsy with potential to address the unmet clinical need of monitoring MDR and treatment failure in myeloma.

Ca2+ mediates extracellular vesicle biogenesis through alternate pathways in malignancy

Extracellular vesicles (EVs) are small membrane vesicles that serve as important intercellular signalling intermediaries in both malignant and non-malignant cells. For EVs formed by the plasma membrane, their biogenesis is characterized by an increase in intracellular calcium followed by successive membrane and cytoskeletal changes. EV-production is significantly higher in malignant cells relative to non-malignant cells and previous work suggests this is dependent on increased calcium mobilization and activity of calpain. However, calcium-signalling pathways involved in malignant and non-malignant EV biogenesis remain unexplored. Here we demonstrate; malignant cells have high basal production of plasma membrane EVs compared to non-malignant cells and this is driven by a calcium–calpain dependent pathway. Resting vesiculation in malignant cells occurs via mobilization of calcium from endoplasmic reticulum (ER) stores rather than from the activity of plasma membrane calcium channels. In the event of ER store depletion however, the store-operated calcium entry (SOCE) pathway is activated to restore ER calcium stores. Depleting both ER calcium stores and blocking SOCE, inhibits EV biogenesis. In contrast, calcium signalling pathways are not activated in resting non-malignant cells. Consequently, these cells are relatively low vesiculators in the resting state. Following cellular activation however, an increase in cytosolic calcium and activation of calpain increase in EV biogenesis. These findings contribute to furthering our understanding of extracellular vesicle biogenesis. As EVs are key mediators in the intercellular transfer of deleterious cancer traits such as cancer multidrug resistance (MDR), understanding the molecular mechanisms governing their biogenesis in cancer is the crucial first step in finding novel therapeutic targets that circumvent EV-mediated MDR.

A Comprehensive Picture of Extracellular Vesicles and Their Contents. Molecular Transfer to Cancer Cells

Critical processes such as growth, invasion, and metastasis of cancer cells are sustained via bidirectional cell-to-cell communication in tissue complex environments. Such communication involves the secretion of soluble factors by stromal cells and/or cancer cells within the tumor microenvironment (TME). Both stromal and cancer cells have been shown to export bilayer nanoparticles: encapsulated regulatory molecules that contribute to cell-to-cell communication. These nanoparticles are known as extracellular vesicles (EVs) being classified into exosomes, microvesicles, and apoptotic bodies. EVs carry a vast repertoire of molecules such as oncoproteins and oncopeptides, DNA fragments from parental to target cells, RNA species (mRNAs, microRNAs, and long non-coding RNA), and lipids, initiating phenotypic changes in TME. According to their specific cargo, EVs have crucial roles in several early and late processes associated with tumor development and metastasis. Emerging evidence suggests that EVs are being investigated for their implication in early cancer detection, monitoring cancer progression and chemotherapeutic response, and more relevant, the development of novel targeted therapeutics. In this study, we provide a comprehensive understanding of the biophysical properties and physiological functions of EVs, their implications in TME, and highlight the applicability of EVs for the development of cancer diagnostics and therapeutics.

Communication in tiny packages: Exosomes as means of tumor-stroma communication

Tumor-derived exosomes are nano-sized vesicles acting as multi-signal devices influencing tumor growth at local and distant sites. Exosomes are derived from the endolysosomal compartment and can shuttle diverse biomolecules like nucleic acids (microRNAs and DNA fragments), lipids, proteins, and even pharmacological compounds from a donor cell to recipient cells. The transfer of cargo to recipient cells enables tumor-derived exosomes to influence diverse cellular functions like proliferation, cell survival, and migration in recipient cells, highlighting tumor-derived exosomes as important players in communication within the tumor microenvironment and at distant sites. In this review, we discuss the mechanisms associated with exosome biogenesis and cargo sorting. In addition, we highlight the communication of tumor-derived exosomes in the tumor microenvironment during different phases of tumor development, focusing on angiogenesis, immune escape mechanisms, drug resistance, and metastasis.

WNT Signaling in Tumors: The Way to Evade Drugs and Immunity

WNT/β-catenin signaling is involved in many physiological processes. Its implication in embryonic development, cell migration, and polarization has been shown. Nevertheless, alterations in this signaling have also been related with pathological events such as sustaining and proliferating the cancer stem cell (CSC) subset present in the tumor bulk. Related with this, WNT signaling has been associated with the maintenance, expansion, and epithelial-mesenchymal transition of stem cells, and furthermore with two distinctive features of this tumor population: therapeutic resistance (MDR, multidrug resistance) and immune escape. These mechanisms are developed and maintained by WNT activation through the transcriptional control of the genes involved in such processes. This review focuses on the description of the best known WNT pathways and the molecules involved in them. Special attention is given to the WNT cascade proteins deregulated in tumors, which have a decisive role in tumor survival. Some of these proteins function as extrusion pumps that, in the course of chemotherapy, expel the drugs from the cells; others help the tumoral cells hide from the immune effector mechanisms. Among the WNT targets involved in drug resistance, the drug extrusion pump MDR-1 (P-GP, ABCB1) and the cell adhesion molecules from the CD44 family are highlighted. The chemokine CCL4 and the immune checkpoint proteins CD47 and PD-L1 are included in the list of WNT target molecules with a role in immunity escape. This pathway should be a main target in cancer therapy as WNT signaling activation is essential for tumor progression and survival, even in the presence of the anti-tumoral immune response and/or antineoplastic drugs. The appropriate design and combination of anti-tumoral strategies, based on the modulation of WNT mediators and/or protein targets, could negatively affect the growth of tumoral cells, improving the efficacy of these types of therapies.

In-hospital outcomes and 5-year mortality following an acute myocardial infarction in patients with a history of cancer: Results from the French registry on Acute ST-elevation or non-ST-elevation myocardial infarction (FAST-MI) 2005 cohort

BACKGROUND

Cancer and acute myocardial infarction (AMI) have important prognostic consequences. Treatment of some cancers may affect coronary artery disease, myocardial function and/or AMI management. Whether the early and long-term mortality of patients with AMI differ according to their history of cancer remains questionable.

AIMS

To determine in-hospital outcomes and 5-year mortality following AMI according to patient history of cancer.

METHODS

The FAST-MI registry is a nationwide French survey collecting data on characteristics, management and outcomes of 3670 consecutive patients admitted for AMI during October 2005.

RESULTS

Overall, 246/3664 patients (6.7%) admitted for an AMI (47.6% with ST-segment elevation myocardial infarction [STEMI]; 52.4% with non-STEMI [NSTEMI]) had a history of cancer. In-hospital mortality was not significantly different for patients with versus without a history of cancer, overall (adjusted odds ratio [OR]: 1.15, 95% confidence interval [CI]: 0.68-1.94; P=0.61) and in patients with STEMI (adjusted OR: 1.37, 95% CI: 0.69-2.71; P=0.37) or NSTEMI (adjusted OR: 0.97, 95% CI: 0.41-2.28; P=0.95). All-cause mortality at 5 years was higher among patients with a history of cancer (adjusted hazard ratio [HR]: 1.36, 95% CI: 1.08-1.69; P=0.008), whereas 5-year cardiovascular mortality did not differ (adjusted HR: 1.17, 95% CI: 0.89-1.53; P=0.25), regardless of whether the patients had STEMI or NSTEMI. Similar results were found in populations matched on a propensity score including baseline characteristics and early management.

CONCLUSION

A history of cancer, per se, does not appear to be a risk factor for increased in-hospital mortality or long-term cardiovascular mortality in patients admitted for AMI.

Microparticles from tumors exposed to radiation promote immune evasion in part by PD-L1

Radiotherapy induces immune-related responses in cancer patients by various mechanisms. Here, we investigate the immunomodulatory role of tumor-derived microparticles (TMPs)—extracellular vesicles shed from tumor cells—following radiotherapy. We demonstrate that breast carcinoma cells exposed to radiation shed TMPs containing elevated levels of immune-modulating proteins, one of which is programmed death-ligand 1 (PD-L1). These TMPs inhibit cytotoxic T lymphocyte (CTL) activity both in vitro and in vivo, and thus promote tumor growth. Evidently, adoptive transfer of CTLs pre-cultured with TMPs from irradiated breast carcinoma cells increases tumor growth rates in mice recipients in comparison with control mice receiving CTLs pre-cultured with TMPs from untreated tumor cells. In addition, blocking the PD-1-PD-L1 axis, either genetically or pharmacologically, partially alleviates TMP-mediated inhibition of CTL activity, suggesting that the immunomodulatory effects of TMPs in response to radiotherapy is mediated, in part, by PD-L1. Overall, our findings provide mechanistic insights into the tumor immune surveillance state in response to radiotherapy and suggest a therapeutic synergy between radiotherapy and immune checkpoint inhibitors.

Intercellular transfer of P-glycoprotein mediates the formation of stable multi-drug resistance in human bladder cancer BIU-87 cells

We investigated the biological characteristics of acquired drug-resistant cells (AqMDRs) formed by intercellular P-glycoprotein (P-gp) transfer and whether AqMDRs can form stable drug-resistant strains. Drug-sensitive BIU-87 cells were co-cultured with doxorubicin (DOX)-resistant derivative BIU-87/DOX cells in transwell chambers for up to 96 h. The presence of P-gp in recipient cell membranes (AqMDRs) was detected by confocal microscopy, CCK-8, western blot, and RT-PCR were used to detect resistance index (RI), P-gp expression and MDR1 mRNA expression in AqMDRs after 0, 4, 8, 16, and 20 passages and frozen/resuscitated twentieth generation AqMDRs. There was an increase in P-gp transfer with longer co-culture times of drug-resistant and sensitive strains. Without DOX, although the AqMDR numbers increased with each passage, the RI and P-gp expression decreased gradually, and the expression level of MDR1 mRNA did not change significantly. With DOX, the RI and P-gp expression increased slightly, and the MDR1 mRNA expression level gradually increased to the BIU-87/DOX level. AqMDRs can grow stably at drug concentrations slightly higher than the IC50 of sensitive strains, which sensitive strains cannot survive. P-gp transfer between cells gradually increases with longer co-culturing of drug-resistant and sensitive strains. The drug resistance of AqMDRs decreases without drug intervention, but with drug intervention, cells can maintain resistance and gradually develop into stable drug-resistant cells. This article has an associated First Person interview with the first author of the paper.

Microvesicles and chemokines in tumor microenvironment: mediators of intercellular communications in tumor progression

Increasing evidence indicates that the ability of cancer cells to convey biological information to recipient cells within the tumor microenvironment (TME) is crucial for tumor progression. Microvesicles (MVs) are heterogenous vesicles formed by budding of the cellular membrane, which are secreted in larger amounts by cancer cells than normal cells. Recently, several reports have also disclosed that MVs function as important mediators of intercellular communication between cancerous and stromal cells within the TME, orchestrating complex pathophysiological processes. Chemokines are a family of small inflammatory cytokines that are able to induce chemotaxis in responsive cells. MVs which selective incorporate chemokines as their molecular cargos may play important regulatory roles in oncogenic processes including tumor proliferation, apoptosis, angiogenesis, metastasis, chemoresistance and immunomodulation, et al. Therefore, it is important to explore the association of MVs and chemokines in TME, identify the potential prognostic marker of tumor, and develop more effective treatment strategies. Here we review the relevant literature regarding the role of MVs and chemokines in TME.

Intercellular Vesicular Transfer by Exosomes, Microparticles and Oncosomes - Implications for Cancer Biology and Treatments

Intercellular communication is a normal feature of most physiological interactions between cells in healthy organisms. While cells communicate directly through intimate physiology contact, other mechanisms of communication exist, such as through the influence of soluble mediators such as growth factors, cytokines and chemokines. There is, however, yet another mechanism of intercellular communication that permits the exchange of information between cells through extracellular vesicles (EVs). EVs are microscopic (50 nm−10 μM) phospholipid bilayer enclosed entities produced by virtually all eukaryotic cells. EVs are abundant in the intracellular space and are present at a cells' normal microenvironment. Irrespective of the EV “donor” cell type, or the mechanism of EV biogenesis and production, or the size and EV composition, cancer cells have the potential to utilize EVs in a manner that enhances their survival. For example, cancer cell EV overproduction confers benefits to tumor growth, and tumor metastasis, compared with neighboring healthy cells. Herein, we summarize the current status of knowledge on different populations of EVs. We review the situations that regulate EV release, and the factors that instruct differential packaging or sorting of EV content. We then highlight the functions of cancer-cell derived EVs as they impact on cancer outcomes, promoting tumor progression, metastases, and the mechanisms by which they facilitate the creation of a pre-metastatic niche. The review finishes by focusing on the beneficial (and challenging) features of tumor-derived EVs that can be adapted and utilized for cancer treatments, including those already being investigated in human clinical trials.

Proteins Regulating Microvesicle Biogenesis and Multidrug Resistance in Cancer

Microvesicles (MV) are emerging as important mediators of intercellular communication. While MVs are important signaling vectors for many physiological processes, they are also implicated in cancer pathology and progression. Cellular activation is perhaps the most widely reported initiator of MV biogenesis, however, the precise mechanism remains undefined. Uncovering the proteins involved in regulating MV biogenesis is of interest given their role in the dissemination of deleterious cancer traits. MVs shed from drug-resistant cancer cells transfer multidrug resistance (MDR) proteins to drug-sensitive cells and confer the MDR phenotype in a matter of hours. MDR is attributed to the overexpression of ABC transporters, primarily P-glycoprotein and MRP1. Their expression and functionality is dependent on a number of proteins. In particular, FERM domain proteins have been implicated in supporting the functionality of efflux transporters in drug-resistant cells and in recipient cells during intercellular transfer by vesicles. Herein, the most recent research on the proteins involved in MV biogenesis and in the dissemination of MV-mediated MDR are discussed. Attention is drawn to unanswered questions in the literature that may prove to be of benefit in ongoing efforts to improve clinical response to chemotherapy and circumventing MDR.

Fatty acids: Adiposity and breast cancer chemotherapy, a bad synergy?

Globally, breast cancer continues to be a major concern in women's health. Lifestyle related risk factors, specifically excess adipose tissue (adiposity) has reached epidemic proportions and has been identified as a major risk factor in the development of breast cancer. Dysfunctional adipose tissue has evoked research focusing on its association with metabolic-related conditions, breast cancer risk and progression. Adipose dysfunction in coordination with immune cells and inflammation, are responsible for accelerated cell growth and survival of cancer cells. Recently, evidence also implicates adiposity as a potential risk factor for chemotherapy resistance. Chemotherapeutic agents have been shown to negatively impact adipose tissue. Since adipose tissue is a major storage site for fatty acids, it is not unlikely that these negative effects may disrupt adipose tissue homeostasis. It is therefore argued that fatty acid composition may be altered due to the chemotherapeutic pharmacokinetics, which in turn could have severe health related outcomes. The underlying molecular mechanisms elucidating the effects of fatty acid composition in adiposity-linked drug resistance are still unclear and under explored. This review focuses on the potential role of adiposity in breast cancer and specifically emphasizes the role of fatty acids in cancer progression and treatment resistance.

Exosomes: A Promising Avenue for the Diagnosis of Breast Cancer

Currently, despite the advances in individualized treatment, breast cancer still remains the deadliest form of cancer in women. Diagnostic, prognostic, and therapy-predictive methods are mainly based on the evaluation of tumor tissue samples and are aimed to improve the overall therapeutic level. Therefore, the exploration of a series of circulating biomarkers, which serve as the information source of tumors and could be obtained by peripheral blood samples, represents a high field of interest. Apart from classical biomarkers, exosomes, which are nanovesicles, are emerging as an accessible and efficient source of cell information. The purpose of this review is to summarize the peculiarities of the presently available breast cancer exosomal biomarkers; the review also provides the prediction of a multitude of potential target genes of exosomal microRNAs using 4 databases.

Exosome-Mediated Transfer of Cancer Cell Resistance to Antiestrogen Drugs

Exosomes are small vesicles which are produced by the cells and released into the surrounding space. They can transfer biomolecules into recipient cells. The main goal of the work was to study the exosome involvement in the cell transfer of hormonal resistance. The experiments were performed on in vitro cultured estrogen-dependent MCF-7 breast cancer cells and MCF-7 sublines resistant to SERM tamoxifen and/or biguanide metformin, which exerts its anti-proliferative effect, at least in a part, via the suppression of estrogen machinery. The exosomes were purified by differential ultracentrifugation, cell response to tamoxifen was determined by MTT test, and the level and activity of signaling proteins were determined by Western blot and reporter analysis. We found that the treatment of the parent MCF-7 cells with exosomes from the resistant cells within 14 days lead to the partial resistance of the MCF-7 cells to antiestrogen drugs. The primary resistant cells and the cells with the exosome-induced resistance were characterized with these common features: decrease in ERα activity and parallel activation of Akt and AP-1, NF-κB, and SNAIL1 transcriptional factors. In general, we evaluate the established results as the evidence of the possible exosome involvement in the transferring of the hormone/metformin resistance in breast cancer cells.

Microparticles as new markers of cardiovascular risk in diabetes and beyond

The term microparticle (MP) identifies a heterogeneous population of vesicles playing a relevant role in the pathogenesis of vascular diseases, cancer and metabolic diseases such as diabetes mellitus. MPs are released by virtually all cell types by shedding during cell growth, proliferation, activation, apoptosis or senescence processes. MPs, in particular platelet- and endothelial-derived MPs (PMPs and EMPs), are increased in a wide range of thrombotic disorders, with an interesting relationship between their levels and disease pathophysiology, activity or progression. EMP plasma levels have been associated with several cardiovascular diseases and risk factors. PMPs are also shown to be involved in the progressive formation of atherosclerotic plaque and development of arterial thrombosis, especially in diabetic patients. Indeed, diabetes is characterised by an increased procoagulant state and by a hyperreactive platelet phenotype, with enhanced adhesion, aggregation, and activation. Elevated MP levels, such as TF+ MPs, have been shown to be one of the procoagulant determinants in patients with type 2 diabetes mellitus. Atherosclerotic plaque constitutes an opulent source of sequestered MPs, called “plaque” MPs. Otherwise, circulating MPs represent a TF reservoir, named “blood-borne” TF, challenging the dogma that TF is a constitutive protein expressed in minute amounts. “Blood-borne” TF is mainly harboured by PMPs, and it can be trapped within the developing thrombus. MP detection and enumeration by polychromatic flow cytometry (PFC) have opened interesting perspectives in clinical settings, particularly for the evaluation of MP numbers and phenotypes as independent marker of cardiovascular risk, disease and outcome in diabetic patients.

Microvesicle removal of anticancer drugs contributes to drug resistance in human pancreatic cancer cells

High mortality in pancreatic cancer patients is partly due to resistance to chemotherapy. We describe that human pancreatic cancer cells acquire drug resistance by a novel mechanism in which they expel and remove chemotherapeutic drugs from the microenvironment via microvesicles (MVs). Using human pancreatic cancer cells that exhibit varied sensitivity to gemcitabine (GEM), we show that GEM exposure triggers the cancer cells to release MVs in an amount that correlates with that cell line's sensitivity to GEM. The importance of MV-release in gaining drug resistance in GEM-resistant pancreatic cancer cells was confirmed when the inhibition of MV-release sensitized the cells to GEM treatment, both in vitro and in vivo. Mechanistically, MVs remove drugs that are internalized into the cells and that are in the microenvironment. The differences between the drug-resistant and drug-sensitive pancreatic cancer cell lines tested here are explained based on the variable content of influx/efflux proteins present on MVs, which directly dictates the ability of MVs either to trap GEM or to allow GEM to flow back to the microenvironment.

Circulating microparticles: challenges and perspectives of flow cytometric assessment

Circulating blood microparticles are likely to play a significant role as messengers of biological information. Their accurate quantification and characterisation is challenging and needs to be carefully designed with preferable usage of fresh minimally-processed blood samples. Utilisation of flow cytometers specifically designed for analysis of small-size particles is likely to provide considerable methodological advantages and should be the preferable option. This viewpoint manuscript provides a critical summary of the key methodological aspects of microparticle analysis.

Note: The review process for this viewpoint article was fully handled by Christian Weber, Editor in Chief.

Mechanisms of Drug Resistance in Cancer: The Role of Extracellular Vesicles

Drug resistance remains a major barrier to the successful treatment of cancer. The mechanisms by which therapeutic resistance arises are multifactorial. Recent evidence has shown that extracellular vesicles (EVs) play a role in mediating drug resistance. EVs are small vesicles carrying a variety of macromolecular cargo released by cells into the extracellular space and can be taken up into recipient cells, resulting in transfer of cellular material. EVs can mediate drug resistance by several mechanisms. They can serve as a pathway for sequestration of cytotoxic drugs, reducing the effective concentration at target sites. They can act as decoys carrying membrane proteins and capturing monoclonal antibodies intended to target receptors at the cell surface. EVs from resistant tumor cells can deliver mRNA, miRNA, long noncoding RNA, and protein inducing resistance in sensitive cells. This provides a new model for how resistance that arises can then spread through a heterogeneous tumor. EVs also mediate cross-talk between cancer cells and stromal cells in the tumor microenvironment, leading to tumor progression and acquisition of therapeutic resistance. In this review, we will describe what is known about how EVs can induce drug resistance, and discuss the ways in which EVs could be used as therapeutic targets or diagnostic markers for managing cancer treatment. While further characterization of the vesiculome and the mechanisms of EV function are still required, EVs offer an exciting opportunity in the fight against cancer.