Mass spectrometric detection of 27-hydroxycholesterol in breast cancer exosomes

LC-MS Approaches for Oxysterols in Various Biosamples

Oxysterols are involved in a plethora of biological processes, including a wide variety of diseases. Therefore, monitoring oxysterols is important for obtaining a deeper understanding of their biological roles and utilizing them as, for example, biomarkers. However, oxysterols can be challenging compounds to study, as they can be very similar in chemical structure but still have distinct biological roles. In addition, oxysterols may be difficult to detect, even with advanced analytical instrumentation. We here focus on the use of liquid chromatography-mass spectrometry (LC-MS) for the analysis of oxysterols, with an additional focus on the steps needed to prepare oxysterols for LC-MS. Steps can include chemical modification of the oxysterols for improving LC-MS sensitivity and adding chemicals that can reveal if the oxysterol levels have been perturbed during preparation. We then round off with descriptions and applications of various sample preparations for different biological matrices, from blood to cells, and biosamples with emerging attention, for example, exosomes and organoids. Taken together, oxysterol analysis is highly compatible with a wide variety of biosamples, allowing for a deeper understanding of these challenging analytes.

The role of exosomes in cancer biology by shedding light on their lipid contents

Exosomes are extracellular bilayer membrane nanovesicles released by cells after the fusion of multivesicular bodies (MVBs) with the plasma membrane. One of the interesting features of exosomes is their ability to carry and transfer various molecules, including lipids, proteins, nucleic acids, and therapeutic cargoes among cells. As intercellular signaling organelles, exosomes participate in various signaling processes such as tumor growth, metastasis, angiogenesis, epithelial-to-mesenchymal transition (EMT), and cell physiology such as cell-to-cell communication. Moreover, these particles are considered good vehicles to shuttle vaccines and drugs for therapeutic applications regarding cancers and tumor cells. These bioactive vesicles are also rich in various lipid molecules such as cholesterol, sphingomyelin (SM), glycosphingolipids, and phosphatidylserine (PS). These lipids play an important role in the formation, release, and function of the exosomes and interestingly, some lipids are used as biomarkers in cancer diagnosis. This review aimed to focus on exosomes lipid content and their role in cancer biology.

Deciphering the Functional Status of Breast Cancers through the Analysis of Their Extracellular Vesicles

Breast cancer (BC) accounts for the highest incidence of tumor-related mortality among women worldwide, justifying the growing search for molecular tools for the early diagnosis and follow-up of BC patients under treatment. Circulating extracellular vesicles (EVs) are membranous nanocompartments produced by all human cells, including tumor cells. Since minimally invasive methods collect EVs, which represent reservoirs of signals for cell communication, these particles have attracted the interest of many researchers aiming to improve BC screening and treatment. Here, we analyzed the cargoes of BC-derived EVs, both proteins and nucleic acids, which yielded a comprehensive list of potential markers divided into four distinct categories, namely, (i) modulation of aggressiveness and growth; (ii) preparation of the pre-metastatic niche; (iii) epithelial-to-mesenchymal transition; and (iv) drug resistance phenotype, further classified according to their specificity and sensitivity as vesicular BC biomarkers. We discuss the therapeutic potential of and barriers to the clinical implementation of EV-based tests, including the heterogeneity of EVs and the available technologies for analyzing their content, to present a consistent, reproducible, and affordable set of markers for further evaluation.

Lipid Metabolic Regulatory Crosstalk Between Cancer Cells and Tumor-Associated Macrophages

In the tumor microenvironment, tumor-associated macrophages (TAMs) are one of the most abundant cell populations, playing key roles in tumorigenesis, chemoresistance, immune evasion, and metastasis. There is an important interaction between TAMs and cancer cells: on the one hand, tumors control the function of infiltrating macrophages, contributing to reprogramming of TAMs, and on the other hand, TAMs affect the growth of cancer cells. This review focuses on lipid metabolism changes in the complex relationship between cancer cells and TAMs. We discuss how lipid metabolism in cancer cells affects macrophage phenotypic and metabolic changes and, subsequently, how altered lipid metabolism of TAMs influences tumor progression. Identifying the metabolic changes that influence the complex interaction between tumor cells and TAMs is also an important step in exploring new therapeutic approaches that target metabolic reprogramming of immune cells to enhance their tumoricidal potential and bypass therapy resistance. Our work may provide new targets for antitumor therapies.

The biological function of tumor-derived extracellular vesicles on metabolism

Multiple studies have shown that extracellular vesicles (EVs) play a key role in the process of information transfer and material transport between cells. EVs are classified into different types according to their sizes, which includes the class of exosomes. In comparison to normal EVs, tumor-derived EVs (TDEs) have both altered components and quantities of contents. TDEs have been shown to help facilitate an environment conducive to the occurrence and development of tumor by regulation of glucose, lipids and amino acids. Furthermore, TDEs can also affect the host metabolism and immune system. EVs have been shown to have multiple clinically useful properties, including the use of TDEs as biomarkers for the early diagnosis of diseases and using the transport properties of exosomes for drug delivery. Targeting the key bioactive cargoes of exosomes could be applied to provide new strategies for the treatment of tumors. In this review, we summarize the finding of studies focused on measuring the effects of TDE on tumor-related microenvironment and systemic metabolism. Video Abstract.

Tspan6 stimulates the chemoattractive potential of breast cancer cells for B cells in an EV- and LXR-dependent manner

The immune microenvironment in breast cancer (BCa) is controlled by a complex network of communication between various cell types. Here, we find that recruitment of B lymphocytes to BCa tissues is controlled via mechanisms associated with cancer cell-derived extracellular vesicles (CCD-EVs). Gene expression profiling identifies the Liver X receptor (LXR)-dependent transcriptional network as a key pathway that controls both CCD-EVs-induced migration of B cells and accumulation of B cells in BCa tissues. The increased accumulation oxysterol ligands for LXR (i.e., 25-hydroxycholesterol and 27-hydroxycholesterol) in CCD-EVs is regulated by the tetraspanin 6 (Tspan6). Tspan6 stimulates the chemoattractive potential of BCa cells for B cells in an EV- and LXR-dependent manner. These results demonstrate that tetraspanins control intercellular trafficking of oxysterols via CCD-EVs. Furthermore, tetraspanin-dependent changes in the oxysterol composition of CCD-EVs and the LXR signaling axis play a key role in specific changes in the tumor immune microenvironment.

Multiparametric Biosensors for Characterizing Extracellular Vesicle Subpopulations

Extracellular vesicles (EVs) are an important intercellular communication conduit for cells that have applications in precision therapy and targeted drug delivery. Small EVs, or exosomes, are a 30-150 nm phospholipid-encased subpopulation of EVs that are particularly difficult to characterize due to their small size and because they are difficult to isolate using conventional methods. In this review, we discuss some recent advances in exosome isolation, purification, and sensing platforms using microfluidics, acoustics, and size exclusion chromatography. We discuss some of the challenges and unanswered questions with respect to understanding exosome size heterogeneity and how modern biosensor technology can be applied to exosome isolation. In addition, we discuss how some advancements in sensing platforms such as colorimetric, fluorescent, electronic, surface plasmon resonance (SPR), and Raman spectroscopy may be applied to exosome detection in multiparametric systems. The application of cryogenic electron tomography and microscopy to understanding exosome ultrastructure will become vital as this field progresses. In conclusion, we speculate on some future needs in the exosome research field and how these technologies could be applied.

Colorimetric Assaying of Exosomal Metabolic Biomarkers

Exosomes released into the extracellular matrix have been reported to contain metabolic biomarkers of various diseases. These intraluminal vesicles are typically found in blood, urine, saliva, breast milk, cerebrospinal fluid, semen, amniotic fluid, and ascites. Analysis of exosomal content with specific profiles of DNA, microRNA, proteins, and lipids can mirror their cellular origin and physiological state. Therefore, exosomal cargos may reflect the physiological processes at cellular level and can potentially be used as biomarkers. Herein, we report an optical detection method for assaying exosomal biomarkers that supersedes the state-of-the-art time consuming and laborious assays such as ELISA and NTA. The proposed assay monitors the changes in optical properties of poly(3-(4-methyl-3'-thienyloxy) propyltriethylammonium bromide) upon interacting with aptamers/peptide nucleic acids in the presence or absence of target biomarkers. As a proof of concept, this study demonstrates facile assaying of microRNA, DNA, and advanced glycation end products in exosomes isolated from human plasma with detection levels of ~1.2, 0.04, and 0.35 fM/exosome, respectively. Thus, the obtained results illustrate that the proposed methodology is applicable for rapid and facile detection of generic exosomal biomarkers for facilitating diseases diagnosis.

Metabolites as extracellular vesicle cargo in health, cancer, pleural effusion, and cardiovascular diseases: An emerging field of study to diagnostic and therapeutic purposes

Extracellular vesicles (EVs) are highly diverse nanoscale membrane-bound structures released from different cell types into the extracellular environment. They play essential functions in cell signaling by transporting their cargo, such as proteins, RNA, DNA, lipids, metabolites, and small molecules, to recipient cells. It has recently been shown that EVs might modulate carcinogenesis by delivering cargo to recipient cells. Furthermore, recent discoveries revealed that changes in plasma-derived EV levels and cargo in subjects with metabolic diseases were documented by many researchers, suggesting that EVs might be a promising source of disease biomarkers. One of the cargos of EVs that has recently attracted the most attention is metabolites. The metabolome of these vesicles introduces a plethora of disease indicators; hence, examining the metabolomics of EVs detected in human biofluids would be an effective approach. On the other hand, metabolites have various roles in biological systems, including the production of energies, synthesizing macromolecules, and serving as signaling molecules and hormones. Metabolome rewiring in cancer and stromal cells is a characteristic of malignancy, but the current understanding of how this affects the metabolite composition and activity of tumor-derived EVs remains in its infancy. Since new findings and studies in the field of exosome biology and metabolism are constantly being published, it is likely that diagnostic and treatment techniques, including the use of exosome metabolites, will be launched in the coming years. Recent years have seen increased interest in the EV metabolome as a possible source for biomarker development. However, our understanding of the role of these molecules in health and disease is still immature. In this work, we have provided the latest findings regarding the role of metabolites as EV cargoes in the pathophysiology of diseases, including cancer, pleural effusion (PE), and cardiovascular disease (CVD). We also discussed the significance of metabolites as EV cargoes of microbiota and their role in host-microbe interaction. In addition, the latest findings on metabolites in the form of EV cargoes as biomarkers for disease diagnosis and treatment are presented in this study.

Current perspectives on clinical use of exosomes as novel biomarkers for cancer diagnosis

Exosomes are a heterogeneous subset of extracellular vesicles (EVs) that biogenesis from endosomes. Besides, exosomes contain a variety of molecular cargoes including proteins, lipids and nucleic acids, which play a key role in the mechanism of exosome formation. Meanwhile, exosomes are involved with physiological and pathological conditions. The molecular profile of exosomes reflects the type and pathophysiological status of the originating cells so could potentially be exploited for diagnostic of cancer. This review aims to describe important molecular cargoes involved in exosome biogenesis. In addition, we highlight exogenous factors, especially autophagy, hypoxia and pharmacology, that regulate the release of exosomes and their corresponding cargoes. Particularly, we also emphasize exosome molecular cargoes as potential biomarkers in liquid biopsy for diagnosis of cancer.

Rhenium(I) conjugates as tools for tracking cholesterol in cells

Cholesterol is vital to control membrane integrity and fluidity, but is also a precursor to produce steroid hormones, bile acids, and vitamin D. Consequently, altered cholesterol biology has been linked to many diseases, including metabolic syndromes and cancer. Defining the intracellular pools of cholesterol and its trafficking within cells is essential to understand both normal cell physiology and mechanisms of pathogenesis. We have synthesized a new cholesterol mimic (ReTEGCholestanol), comprising a luminescent rhenium metal complex and a cholestanol targeting unit, linked using a tetraethylene glycol (TEG) spacer. ReTEGCholestanol demonstrated favourable imaging properties and improved water solubility when compared to a cholesterol derivative, and structurally related probes lacking the TEG linker. A non-malignant and three malignant prostate cell lines were used to characterize the uptake and intracellular distribution of ReTEGCholestanol. The ReTEGCholestanol complex was effectively internalized and mainly localized to late endosomes/lysosomes in non-malignant PNT1a cells, while in prostate cancer cells it also accumulated in early endosomes and multivesicular bodies, suggesting disturbed cholesterol biology in the malignant cells. The ReTEGCholestanol is a novel imaging agent for visualizing endosomal uptake and trafficking, which may be used to define cholesterol related biology including membrane integration and altered lipid trafficking/processing.

Our evolving understanding of how 27-hydroxycholesterol influences cancer

Cholesterol has been implicated in the pathophysiology and progression of several cancers now, although the mechanisms by which it influences cancer biology are just emerging. Two likely contributing mechanisms are the ability for cholesterol to directly regulate signaling molecules within the membrane, and certain metabolites acting as signaling molecules. One such metabolite is the oxysterol 27-hydroxycholesterol (27HC), which is a primary metabolite of cholesterol synthesized by the enzyme Cytochrome P450 27A1 (CYP27A1). Physiologically, 27HC is involved in the regulation of cholesterol homeostasis and contributes to cholesterol efflux through liver X receptor (LXR) and inhibition of de novo cholesterol synthesis through the insulin-induced proteins (INSIGs). 27HC is also a selective modulator of the estrogen receptors. An increasing number of studies have identified its importance in cancer progression of various origins, especially in breast cancer. In this review, we discuss the physiological roles of 27HC targeting these two nuclear receptors and the subsequent contribution to cancer progression. We describe how 27HC promotes tumor growth directly through cancer-intrinsic factors, and indirectly through its immunomodulatory roles which lead to decreased immune surveillance and increased tumor invasion. This review underscores the importance of the cholesterol metabolic pathway in cancer progression and the potential therapeutic utility of targeting this metabolic pathway.

Metabolomic Profiling of Blood-Derived Microvesicles in Breast Cancer Patients

Malignant cells differ from benign ones in their metabolome and it is largely unknown whether this difference is reflected in the metabolic profile of their microvesicles (MV), which are secreted into the blood of cancer patients. Here, they are present together with MV from the various blood and endothelial cells. Harvesting MV from 78 breast cancer patients (BC) and 30 controls, we characterized the whole blood MV metabolome using targeted and untargeted mass spectrometry. Especially (lyso)-phosphatidylcholines and sphingomyelins were detected in a relevant abundance. Eight metabolites showed a significant discriminatory power between BC and controls. High concentrations of lysoPCaC26:0 and PCaaC38:5 were associated with shorter overall survival. Comparing BC subtype-specific metabolome profiles, 24 metabolites were differentially expressed between luminal A and luminal B. Pathway analysis revealed alterations in the glycerophospholipid metabolism for the whole cancer cohort and in the ether lipid metabolism for the molecular subtype luminal B. Although this mixture of blood-derived MV contains only a minor number of tumor MV, a combination of metabolites was identified that distinguished between BC and controls as well as between molecular subtypes, and was predictive for overall survival. This suggests that these metabolites represent promising biomarkers and, moreover, that they may be functionally relevant for tumor progression.

Recent advances in microscale separation techniques for lipidome analysis

This review paper highlights the recent research on liquid-phase microscale separation techniques for lipidome analysis over the last 10 years, mainly focusing on capillary liquid chromatography (LC) and capillary electrophoresis (CE) coupled with mass spectrometry (MS). Lipids are one of the most important classes of biomolecules which are involved in the cell membrane, energy storage, signal transduction, and so on. Since lipids include a variety of hydrophobic compounds including numerous structural isomers, lipidomes are a challenging target in bioanalytical chemistry. MS is the key technology that comprehensively identifies lipids; however, separation techniques like LC and CE are necessary prior to MS detection in order to avoid ionization suppression and resolve structural isomers. Separation techniques using μm-scale columns, such as a fused silica capillary and microfluidic device, are effective at realizing high-resolution separation. Microscale separation usually employs a nL-scale flow, which is also compatible with nanoelectrospray ionization-MS that achieves high sensitivity. Owing to such analytical advantages, microscale separation techniques like capillary/microchip LC and CE have been employed for more than 100 lipidome studies. Such techniques are still being evolved and achieving further higher resolution and wider coverage of lipidomes. Therefore, microscale separation techniques are promising as the fundamental technology in next-generation lipidome analysis.

Protein biomarkers in breast cancer-derived extracellular vesicles for use in liquid biopsies

Breast cancer is the most common malignant disease in women worldwide. Early diagnosis and treatment can greatly improve the management of breast cancer. Liquid biopsies are becoming convenient detection methods for diagnosing and monitoring breast cancer due to their noninvasiveness and ability to provide real-time feedback. A range of liquid biopsy markers, including circulating tumor proteins, circulating tumor cells, and circulating tumor nucleic acids, have been implemented for breast cancer diagnosis and prognosis, with each having its own advantages and limitations. Circulating extracellular vesicles are messengers of intercellular communication that are packed with information from mother cells and are found in a wide variety of bodily fluids; thus, they are emerging as ideal candidates for liquid biopsy biomarkers. In this review, we summarize extracellular vesicle protein markers that can be potentially used for the early diagnosis and prognosis of breast cancer or determining its specific subtypes.

Ionising Radiation Promotes Invasive Potential of Breast Cancer Cells: The Role of Exosomes in the Process

Along with the cells that are exposed to radiation, non-irradiated cells can unveil radiation effects as a result of intercellular communication, which are collectively defined as radiation induced bystander effects (RIBE). Exosome-mediated signalling is one of the core mechanisms responsible for multidirectional communication of tumor cells and their associated microenvironment, which may result in enhancement of malignant tumor phenotypes. Recent studies show that exosomes and exosome-mediated signalling also play a dynamic role in RIBE in cancer cell lines, many of which focused on altered exosome cargo or their effects on DNA damage. However, there is a lack of knowledge regarding how these changes in exosome cargo are reflected in other functional characteristics of cancer cells from the aspects of invasiveness and metastasis. Therefore, in the current study, we aimed to investigate exosome-mediated bystander effects of 2 Gy X-ray therapeutic dose of ionizing radiation on the invasive potential of MCF-7 breast cancer cells in vitro via assessing Matrigel invasion potential, epithelial mesenchymal transition (EMT) characteristics and the extent of glycosylation, as well as underlying plausible molecular mechanisms. The findings show that exosomes derived from irradiated MCF-7 cells enhance invasiveness of bystander MCF-7 cells, possibly through altered miRNA and protein content carried in exosomes.

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.

Extracellular Vesicles-The Next Frontier in Endocrinology

Extracellular vesicles (EVs), including exosomes, are emerging as important carriers of signals in normal and pathological physiology. As EVs are a long-range communication or signaling modality-just like hormones are-the field of endocrinology is uniquely poised to offer insight into their functional biology and regulation. EVs are membrane-bound particles secreted by many different cell types and can have local or systemic effects, being transported in body fluids. They express transmembrane proteins, some of which are shared between EVs and some being specific to the tissue of origin, that can interact with target cells directly (much like hormones can). They also contain cargo within them that includes DNA, RNA, miRNA, and various metabolites. They can fuse with target cells to empty their cargo and alter their target cell physiology in this way also. Similar to the endocrine system, the EV system is likely to be under homeostatic control, making the regulation of their biogenesis and secretion important aspects to study. In this review, we briefly highlight select examples of how EVs are implicated in normal physiology and disease states. We also discuss what is known about their biogenesis and regulation of secretion. We hope that this paper inspires the endocrinology field to use our collective expertise to explore these new multimodal "hormones."

The Cholesterol Metabolite 27HC Increases Secretion of Extracellular Vesicles Which Promote Breast Cancer Progression

Cholesterol has been implicated in the clinical progression of breast cancer, a disease that continues to be the most commonly diagnosed cancer in women. Previous work has identified the cholesterol metabolite 27-hydroxycholesterol (27HC) as a major mediator of the effects of cholesterol on breast tumor growth and progression. 27HC can act as an estrogen receptor (ER) modulator to promote the growth of ERα+ tumors, and as a liver X receptor (LXR) ligand in myeloid immune cells to establish an immune-suppressive program. In fact, the metastatic properties of 27HC require the presence of myeloid cells with neutrophils (polymorphonuclear neutrophils; PMNs) being essential for the increase in lung metastasis in murine models. In an effort to further elucidate the mechanisms by which 27HC alters breast cancer progression, we made the striking finding that 27HC promoted the secretion of extracellular vesicles (EVs), a diverse assortment of membrane bound particles that includes exosomes. The resulting EVs had a size distribution that was skewed slightly larger than EVs generated by treating cells with vehicle. The increase in EV secretion and size was consistent across 3 different subtypes: primary murine PMNs, RAW264.7 monocytic cells, and 4T1 murine mammary cancer cells. Label-free analysis of 27HC-EVs indicated that they had a different metabolite composition to those from vehicle-treated cells. Importantly, 27HC-EVs from primary PMNs promoted tumor growth and metastasis in 2 different syngeneic models, demonstrating the potential role of 27HC-induced EVs in the progression of breast cancer. EVs from PMNs were taken up by cancer cells, macrophages, and PMNs, but not T cells. Since EVs did not alter proliferation of cancer cells, it is likely that their protumor effects are mediated through interactions with myeloid cells. Interestingly, RNA-seq analysis of tumors from 27HC-EV-treated mice do not display significantly altered transcriptomes, suggesting that the effects of 27HC-EVs occur early on in tumor establishment and growth. Future work will be required to elucidate the mechanisms by which 27HC increases EV secretion, and how these EVs promote breast cancer progression. Collectively, however, our data indicate that EV secretion and content can be regulated by a cholesterol metabolite, which may have detrimental effects in terms of disease progression, important findings given the prevalence of both breast cancer and hypercholesterolemia.

Cellular crosstalk in cardioprotection: Where and when do reactive oxygen species play a role?

A well-balanced intercellular communication between the different cells within the heart is vital for the maintenance of cardiac homeostasis and function. Despite remarkable advances on disease management and treatment, acute myocardial infarction remains the major cause of morbidity and mortality worldwide. Gold standard reperfusion strategies, namely primary percutaneous coronary intervention, are crucial to preserve heart function. However, reestablishment of blood flow and oxygen levels to the infarcted area are also associated with an accumulation of reactive oxygen species (ROS), leading to oxidative damage and cardiomyocyte death, a phenomenon termed myocardial reperfusion injury. In addition, ROS signaling has been demonstrated to regulate multiple biological pathways, including cell differentiation and intercellular communication. Given the importance of cell-cell crosstalk in the coordinated response after cell injury, in this review, we will discuss the impact of ROS in the different forms of inter- and intracellular communication, as well as the role of gap junctions, tunneling nanotubes and extracellular vesicles in the propagation of oxidative damage in cardiac diseases, particularly in the context of ischemia/reperfusion injury.

Tumor-derived exosomal components: the multifaceted roles and mechanisms in breast cancer metastasis

Breast cancer (BC) is the most frequently invasive malignancy and the leading cause of tumor-related mortality among women worldwide. Cancer metastasis is a complex, multistage process, which eventually causes tumor cells to colonize and grow at the metastatic site. Distant organ metastases are the major obstacles to the management of advanced BC patients. Notably, exosomes are defined as specialized membrane-enclosed extracellular vesicles with specific biomarkers, which are found in a wide variety of body fluids. Recent studies have demonstrated that exosomes are essential mediators in shaping the tumor microenvironment and BC metastasis. The transferred tumor-derived exosomes modify the capability of invasive behavior and organ-specific metastasis in recipient cells. BC exosomal components, mainly including noncoding RNAs (ncRNAs), proteins, lipids, are the most investigated components in BC metastasis. In this review, we have emphasized the multifaceted roles and mechanisms of tumor-derived exosomes in BC metastasis based on these important components. The underlying mechanisms mainly include the invasion behavior change, tumor vascularization, the disruption of the vascular barrier, and the colonization of the targeted organ. Understanding the significance of tumor-derived exosomal components in BC metastasis is critical for yielding novel routes of BC intervention.

Mass spectrometry in the lipid study of cancer

Introduction: Cancer is a heterogeneous disease that exploits various metabolic pathways to meet the demand for increased energy and structural components. Lipids are biomolecules that play essential roles as high energy sources, mediators, and structural components of biological membranes. Accumulating evidence has established that altered lipid metabolism is a hallmark of cancer.Areas covered: Mass spectrometry (MS) is a label-free analytical tool that can simultaneously identify and quantify hundreds of analytes. To date, comprehensive lipid studies exclusively rely on this technique. Here, we reviewed the use of MS in the study of lipids in various cancers and discuss its instrumental limitations and challenges.Expert opinion: MS and MS imaging have significantly contributed to revealing altered lipid metabolism in a variety of cancers. Currently, a single MS approach cannot profile the entire lipidome because of its lack of sensitivity and specificity for all lipid classes. For the metabolic pathway investigation, lipid study requires the integration of MS with other molecular approaches. Future developments regarding the high spatial resolution, mass resolution, and sensitivity of MS instruments are warranted.

Obesity, Type 2 Diabetes, and Cancer Risk

Obesity and type 2 diabetes have both been associated with increased cancer risk and are becoming increasingly prevalent. Metabolic abnormalities such as insulin resistance and dyslipidemia are associated with both obesity and type 2 diabetes and have been implicated in the obesity-cancer relationship. Multiple mechanisms have been proposed to link obesity and diabetes with cancer progression, including an increase in insulin/IGF-1 signaling, lipid and glucose uptake and metabolism, alterations in the profile of cytokines, chemokines, and adipokines, as well as changes in the adipose tissue directly adjacent to the cancer sites. This review aims to summarize and provide an update on the epidemiological and mechanistic evidence linking obesity and type 2 diabetes with cancer, focusing on the roles of insulin, lipids, and adipose tissue.

Membrane organization and intracellular transport of a fluorescent analogue of 27-hydroxycholesterol

Oxysterols are cholesterol metabolites with multiple functions in controlling cellular homeostasis. In particular, 27-hydroxycholesterol (27-OH-Chol) has been shown to regulate a variety of physiological functions, but little is known about its uptake, intracellular trafficking, and efflux from cells. This is largely due to a lack of suitable analogs of 27-OH-Chol, which mimic this oxysterol closely. Here, we present the intrinsically fluorescent 27-hydroxy-cholestatrienol (27-OH-CTL), which differs from 27-OH-Chol only by having two additional double bonds in the steroid ring system. Based on molecular dynamics (MD) simulations, we show that 27-OH-CTL possesses almost identical membrane properties compared to 27-OH-Chol. By comparative imaging of 27-OH-CTL and of the cholesterol analogue cholestatrienol (CTL) in living cells, we assess the impact of a single hydroxy group on sterol trafficking. We find that human fibroblasts take up more CTL than 27-OH-CTL, but efflux the oxysterol analogue more efficiently. For both sterols, efflux includes shedding of vesicles from the plasma membrane. Intracellular, 27-OH-CTL accumulates primarily in lipid droplets (LDs), while CTL is mostly found in endosomes and lysosomes. Using fluorescence recovery after photobleaching (FRAP), we find for both sterols a rapidly exchanging pool, which moves orders of magnitude faster than sterol containing vesicles and LDs. In summary, by applying a new fluorescent derivative of 27-OH-Chol we demonstrate that human cells can distinguish sterols based on a single hydroxy group in the side chain, resulting in different transport itineraries, dynamics, and efflux kinetics. Both intrinsically fluorescent cholesterol and oxysterol analogues show rapid non-vesicular transport in human fibroblasts.

Progress in exosome associated tumor markers and their detection methods

Exosomes are secreted by cells and are widely present in body fluids. Exosomes contain various molecular constituents of their cells of origin such as proteins, mRNA, miRNAs, DNA, lipid and glycans which are very similar as the content in tumor cells. These contents play an important role in various stages of tumor development, and make the tumor-derived exosome as a hot and emerging biomarker for various cancers diagnosis and management in non-invasive manner. The present problems of exosome isolation and detection hinder the application of exosomes. With the development of exosome isolation and detection technology, the contents of exosomes can be exploited for early cancer diagnosis. This review summarizes the recent progress on exosome-associated tumor biomarkers and some new technologies for exosome isolation and detection. Furthermore, we have also discussed the future development direction in exosome analysis methods.

The crosstalk: exosomes and lipid metabolism

Exosomes have been considered as novel and potent vehicles of intercellular communication, instead of "cell dust". Exosomes are consistent with anucleate cells, and organelles with lipid bilayer consisting of the proteins and abundant lipid, enhancing their "rigidity" and "flexibility". Neighboring cells or distant cells are capable of exchanging genetic or metabolic information via exosomes binding to recipient cell and releasing bioactive molecules, such as lipids, proteins, and nucleic acids. Of note, exosomes exert the remarkable effects on lipid metabolism, including the synthesis, transportation and degradation of the lipid. The disorder of lipid metabolism mediated by exosomes leads to the occurrence and progression of diseases, such as atherosclerosis, cancer, non-alcoholic fatty liver disease (NAFLD), obesity and Alzheimer's diseases and so on. More importantly, lipid metabolism can also affect the production and secretion of exosomes, as well as interactions with the recipient cells. Therefore, exosomes may be applied as effective targets for diagnosis and treatment of diseases. Video abstract.

Oxysterols: From physiological tuners to pharmacological opportunities

Oxysterols are oxygenated forms of cholesterol generated via autooxidation by free radicals and ROS, or formed enzymically by a variety of enzymes such as those involved in the synthesis of bile acids. Although found at very low concentrations in vivo, these metabolites play key roles in health and disease, particularly in development and regulating immune cell responses, by binding to effector proteins such as LXRα, RORγ and Insig and directly or indirectly regulating transcriptional programmes that affect cell metabolism and function. In this review, we summarise the routes by which oxysterols can be generated and subsequently modified to other oxysterol metabolites and highlight their diverse and profound biological functions and opportunities to alter their levels using pharmacological approaches. LINKED ARTICLES: This article is part of a themed issue on Oxysterols, Lifelong Health and Therapeutics. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.16/issuetoc.

Extracellular vesicle-associated lipids in central nervous system disorders

Increasing evidence indicates that lipid metabolism is disturbed in central nervous system (CNS) disorders, such as multiple sclerosis, Alzheimer's, and Parkinson's disease. Extracellular vesicles (EVs), including exosomes and microvesicles, are nanosized particles that play an essential role in intercellular communication and tissue homeostasis by transporting diverse biologically active molecules, including a large variety of lipid species. In the last decade, studies defined that changes in the EV lipidome closely correlate with disease-progression and -remission in CNS disorders. In this review, we summarize and discuss these changes in the EV lipidome and elaborate on the impact of different EV-associated lipids on pathological processes in CNS disorders. We conclude that EV-associated lipids are closely associated with neuroinflammation, CNS repair, and pathological protein aggregation in CNS disorders, and that modulation of the EV lipidome represents a promising therapeutic strategy to halt disease progression in multiple sclerosis, Alzheimer's, and Parkinson's disease. Moreover, we predict that disease-stage specific EV-associated lipid signatures can be invaluable markers for the diagnosis and early detection of CNS disorders in the future.

Impaired LXRα Phosphorylation Attenuates Progression of Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is a very common indication for liver transplantation. How fat-rich diets promote progression from fatty liver to more damaging inflammatory and fibrotic stages is poorly understood. Here, we show that disrupting phosphorylation at Ser196 (S196A) in the liver X receptor alpha (LXRα, NR1H3) retards NAFLD progression in mice on a high-fat-high-cholesterol diet. Mechanistically, this is explained by key histone acetylation (H3K27) and transcriptional changes in pro-fibrotic and pro-inflammatory genes. Furthermore, S196A-LXRα expression reveals the regulation of novel diet-specific LXRα-responsive genes, including the induction of Ces1f, implicated in the breakdown of hepatic lipids. This involves induced H3K27 acetylation and altered LXR and TBLR1 cofactor occupancy at the Ces1f gene in S196A fatty livers. Overall, impaired Ser196-LXRα phosphorylation acts as a novel nutritional molecular sensor that profoundly alters the hepatic H3K27 acetylome and transcriptome during NAFLD progression placing LXRα phosphorylation as an alternative anti-inflammatory or anti-fibrotic therapeutic target.

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LXRαS196A induces liver steatosis and prevents cholesterol accumulation

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LXRαS196A reduces progression to hepatic inflammation and fibrosis

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LXRαS196A modulates hepatic chromatin acetylation

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LXRαS196A reveals unique dual LXRα phosphorylation and diet-responsive genes

Recent achievements in exosomal biomarkers detection by nanomaterials-based optical biosensors - A review

Exosomal biomarkers including tumor-derived exosomes, exosomal surface proteins and exosomal nucleic acids have emerged as one of the most important and general cancer biomarkers in modern biomedical science. These indicators can provide momentous biological information for early diagnosis and treatment of cancer. Recently, numerous studies have been conducted to design biosensors for exosomal biomarkers detection and profiling with high sensitivity and strong applied ability. Among these biosensors, nanomaterial-based optical biosensors are prospective future platforms for rapid and cost-effective detection of exosomal biomarkers. Firstly, we have focused on the progress and advancements in different optical-transducing approaches (Surface-Enhanced Raman Scattering, Surface Plasmon Resonance, Colorimetry, Immunochromatographic assay, Chemiluminescence, Electrochemiluminescence, and fluorescence) for detecting and profiling exosomal biomarkers. Additionally, we have summarized strengths and drawbacks of each strategy. Finally, challenges and future outlooks in developing efficient nanomaterial-based optical biosensor systems for exosomal tumor biomarkers detection have been discussed. The review will exhibit an overview of this field and provide meaningful information for scientific researchers.

Cholesterol, Oxysterols and LXRs in Breast Cancer Pathophysiology

Breast cancer is the most frequent cancer among women. In 2018, it is estimated that 627,000 women died from breast cancer. This is approximately 15% of all cancer deaths among women (WHO 2018). Breast cancer is a multifactorial chronic disease. While important progress has been made to treat patients, many questions regarding aspects of this disease relating to carcinogenesis are still open. During carcinogenesis, cells exhibit cholesterol homeostasis deregulation. This results in an accumulation of intracellular cholesterol, which is required to sustain their high growth rate. Cholesterol efflux and influx are two metabolic pathways that are necessary to prevent cholesterol accumulation in the cells. Liver X receptors (LXRs) are nuclear receptors that, upon activation, induce the expression of ABC transporters, responsible for promoting cholesterol efflux, and the expression of IDOL (inducible degrader of low-density lipoprotein receptor), in charge of reducing cholesterol influx. Oxysterols, oxygenated derivatives of cholesterol formed through different pathways, have been discovered as LXR-specific ligands. Some oxysterols are involved in tumor formation while others are considered anti-tumor agents. In the present review, we discuss the involvement of cholesterol, oxysterols and LXRs in breast cancer pathophysiology, with an emphasis on the biological effects of LXR ligands.

Lipidomic characterization of exosomes isolated from human plasma using various mass spectrometry techniques

Ultrahigh-performance supercritical fluid chromatography - mass spectrometry (UHPSFC/MS), ultrahigh-performance liquid chromatography - mass spectrometry (UHPLC/MS), and matrix-assisted laser desorption/ionization (MALDI) - MS techniques were used for the lipidomic characterization of exosomes isolated from human plasma. The high-throughput methods UHPSFC/MS and UHPLC/MS using a silica-based column containing sub-2 μm particles enabled the lipid class separation and the quantitation based on exogenous class internal standards in <7 minute run time. MALDI provided the complementary information on anionic lipid classes, such as sulfatides. The nontargeted analysis of 12 healthy volunteers was performed, and absolute molar concentration of 244 lipids in exosomes and 191 lipids in plasma belonging to 10 lipid classes were quantified. The statistical evaluation of data included principal component analysis, orthogonal partial least square discriminant analysis, S-plots, p-values, T-values, fold changes, false discovery rate, box plots, and correlation plots, which resulted in the information on lipid changes in exosomes in comparison to plasma. The major changes were detected in the composition of triacylglycerols, diacylglycerols, phosphatidylcholines, and lysophosphatidylcholines, whereby sphingomyelins, phosphatidylinositols, and sulfatides showed rather similar profiles in both biological matrices.

Cancer-Derived Exosomes: Their Role in Cancer Biology and Biomarker Development

Exosomes are a subset of tiny extracellular vesicles manufactured by all cells and are present in all body fluids. They are produced actively in tumor cells, which are released and utilized to facilitate tumor growth. Their characteristics enable them to assist major cancer hallmarks, leveraged by cancer cells in fostering cancer growth and spread while implementing ways to escape elimination from the host environment. This review updates on the latest progress on the roles of cancer-derived exosomes, of 30-100 nm in size, in deregulating paracrine trafficking in the tumor microenvironment and circulation. Thus, exosomes are being exploited in diagnostic biomarker development, with its potential in clinical applications as therapeutic targets utilized in exosome-based nanoparticle drug delivery strategies for cancer therapy. Ongoing studies were retrieved from PubMed^® and Scopus database and ClinicalTrials.gov registry for review, highlighting how cancer cells from entirely different cell lines rely on genetic information carried by their exosomes for homotypic and heterotypic intercellular communications in the microenvironment to favor proliferation and invasion, while establishing a pre-metastatic niche in welcoming cancer cells' arrival. We will elaborate on the trafficking of tumor-derived exosomes in fostering cancer proliferation, invasion, and metastasis in hematopoietic (leukemia and myeloma), epithelial (breast cancer), and mesenchymal (soft tissue sarcoma and osteosarcoma) cancers. Cancer-derived exosomal trafficking is observed in several types of liquid or solid tumors, confirming their role as cancer hallmark enabler. Their enriched genetic signals arising from their characteristic DNA, RNA, microRNA, and lncRNA, along with specific gene expression profiles, protein, or lipid composition carried by the exosomal cargo shed into blood, saliva, urine, ascites, and cervicovaginal lavage, are being studied as a diagnostic, prognostic, or predictive cancer biomarker. We reveal the latest research efforts in exploiting the use of nanoparticles to improve the overall cancer diagnostic capability in the clinic.

An emerging focus on lipids in extracellular vesicles

Extracellular vesicles contain a lipid bilayer membrane that protects the encapsulated material, such as proteins, nucleic acids, lipids and metabolites, from the extracellular environment. These vesicles are released from cells via different mechanisms. During recent years extracellular vesicles have been studied as possible biomarkers for different diseases, as biological nanoparticles for drug delivery, and in basic studies as a tool to understand the structure of biological membranes and the mechanisms involved in vesicular trafficking. Lipids are essential molecular components of extracellular vesicles, but at the moment our knowledge about the lipid composition and the function of lipids in these vesicles is limited. However, the interest of the research community in these molecules is increasing as their role in extracellular vesicles is starting to be acknowledged. In this review, we will present the status of the field and describe what is needed to bring it forward.

Omics analysis of oxysterols to better understand their pathophysiological role

High amounts of cholesterol have been definitely associated with the pathogenesis of several diseases, including metabolic and neurodegenerative disorders, cardiovascular diseases, and cancer. In all these pathologies the exacerbation of pro-oxidant and inflammatory responses is a consistent feature. In this scenario, species derived from enzymatic and non-enzymatic cholesterol oxidation, namely oxysterols, are strongly suspected to play a primary role. The consideration of these bioactive lipids is therefore helpful in investigating pathological mechanisms and may also acquire clinical value for the diagnosis and treatment of diseases. For this purpose and considering that a great number of oxysterols may be present together in the body, the employment of lipidomics technology certainly represents a powerful strategy for the simultaneous detection and characterization of these compounds in biological specimens. In this review, we will discuss the applicability of the lipidomics approach in the study of the association between oxysterols and diseases.

Novel strategies for enhancing shotgun lipidomics for comprehensive analysis of cellular lipidomes

Shotgun lipidomics is one of the most powerful tools in analysis of cellular lipidomes in lipidomics, which directly analyzes lipids from lipid extracts of diverse biological samples with high accuracy/precision. However, despite its great advances in high throughput analysis of cellular lipidomes, low coverage of poorly ionized lipids, especially those species in very low abundance, and some types of isomers within complex lipid extracts by shotgun lipidomics remains a huge challenge. In the past few years, many strategies have been developed to enhance shotgun lipidomics for comprehensive analysis of lipid species. Chemical derivatization represents one of the most attractive and effective strategies, already receiving considerable attention. This review focuses on novel advanced derivatization strategies for enhancing shotgun lipidomics. It is anticipated that with the development of enhanced strategies, shotgun lipidomics can make greater contributions to biological and biomedical research.

3D cell culture models and organ-on-a-chip: Meet separation science and mass spectrometry

In vitro derived simplified 3D representations of human organs or organ functionalities are predicted to play a major role in disease modeling, drug development, and personalized medicine, as they complement traditional cell line approaches and animal models. The cells for 3D organ representations may be derived from primary tissues, embryonic stem cells or induced pluripotent stem cells and come in a variety of formats from aggregates of individual or mixed cell types, self-organizing in vitro developed "organoids" and tissue mimicking chips. Microfluidic devices that allow long-term maintenance and combination with other tissues, cells or organoids are commonly referred to as "microphysiological" or "organ-on-a-chip" systems. Organ-on-a-chip technology allows a broad range of "on-chip" and "off-chip" analytical techniques, whereby "on-chip" techniques offer the possibility of real time tracking and analysis. In the rapidly expanding tool kit for real time analytical assays, mass spectrometry, combined with "on-chip" electrophoresis, and other separation approaches offer attractive emerging tools. In this review, we provide an overview of current 3D cell culture models, a compendium of current analytical strategies, and we make a case for new approaches for integrating separation science and mass spectrometry in this rapidly expanding research field.

Tumor-derived extracellular vesicles: insights into bystander effects of exosomes after irradiation

This review article aims to address the kinetic of TDEs in cancer cells pre- and post-radiotherapy. Radiotherapy is traditionally used for the treatment of multiple cancer types; however, there is growing evidence to show that radiotherapy exerts NTEs on cells near to the irradiated cells. In tumor mass, irradiated cells can affect non-irradiated cells in different ways. Of note, exosomes are nano-scaled cell particles releasing from tumor cells and play key roles in survival, metastasis, and immunosuppression of tumor cells. Recent evidence indicated that irradiation has the potential to affect the dynamic of different signaling pathways such as exosome biogenesis. Indeed, exosomes act as intercellular mediators in various cell communication through transmitting bio-molecules. Due to their critical roles in cancer biology, exosomes are at the center of attention. TDEs contain an exclusive molecular signature that they may serve as tumor biomarker in the diagnosis of different cancers. Interestingly, radiotherapy and IR could also contribute to altering the dynamic of exosome secretion. Most probably, the content of exosomes in irradiated cells is different compared to exosomes originated from the non-irradiated BCs. Irradiated cells release exosomes with exclusive content that mediate NTEs in BCs. Considering variation in cell type, IR doses, and radio-resistance or radio-sensitivity of different cancers, there is, however, contradictions in the feature and activity of irradiated exosomes on neighboring cells.

Fast liquid chromatography-mass spectrometry reveals side chain oxysterol heterogeneity in breast cancer tumour samples

Oxysterols can contribute to proliferation of breast cancer through activation of the Estrogen Receptors, and to metastasis through activation of the Liver X Receptors. Endogenous levels of both esterified and free sidechain-hydroxylated oxysterols were examined in breast cancer tumours from Estrogen Receptor positive and negative breast tumours, using a novel fast liquid chromatography tandem mass spectrometry method. Multiple aliquots of five milligram samples of 22 tumours were analysed for oxysterol content to assess intra- and inter-tumour variation. Derivatization was performed with Girard T reagent (with and without alkaline hydrolysis) and sample clean-up was performed using a robust automatic on-line column switching system ("AFFL"). Oxysterols were separated isocratically on a 2.1 mm inner diameter column packed with ACE SuperPhenylHexyl core shell particles using a mobile phase consisting of 0.1% formic acid in H₂O/methanol/acetonitrile (57/10/33, v/v/v) followed by a wash out step (0.1% formic acid in methanol/acetonitrile, 50/50, v/v). The total analysis time, including sample clean-up and column reconditioning, was 8 min (80% time reduction compared to other on-line systems). Analysis revealed large intra-tumour variations of sidechain oxysterols, resulting in no significant differences in endogenous oxysterols levels between Estrogen Receptor positive and Estrogen Receptor negative breast cancers. However, a correlation between esterified and free 27-hydroxycholesterol was observed. The same correlation was not observed for 24S-hydroxycholesterol or 25-hydroxycholesterol. The oxysterol heterogeneity of tumour tissue is a critical factor when assessing the role of these lipids in cancer.

Current Progresses of Exosomes as Cancer Diagnostic and Prognostic Biomarkers

Cancer related exosomes are nano-size membrane vesicles that play important roles in tumor microenvironment. Emerging evidence indicates that exosomes can load unique cargoes, including proteins and nucleic acids that reflect the condition of tumor. Therefore, exosomes are being used as diagnostic and prognostic biomarkers for various cancers. In this review, we describe the current progresses of cancer related exosomes, including their biogenesis, molecular contents, biological functions, sources where they are derived from, and methods for their detection. We will also discuss the current exosomal biomarkers and the utilization of them for early diagnosis and prognostics in cancer.

Ultracentrifugation versus kit exosome isolation: nanoLC-MS and other tools reveal similar performance biomarkers, but also contaminations

Aim

For isolation of exosomes, differential ultracentrifugation and an isolation kit from a major vendor were compared.

Materials & methods

'Case study' exosomes isolated from patient-derived cells from glioblastoma multiforme and a breast cancer cell line were analyzed.

Results

Transmission electron microscopy, dynamic light scattering, western blotting, and so forth, revealed comparable performance. Potential protein biomarkers for both diseases were also identified in the isolates using nanoLC-MS. Western blotting and nanoLC-MS also revealed negative exosome markers regarding both isolation approaches.

Conclusion

The two isolation methods had an overall similar performance, but we hesitate to use the term 'exosome isolation' as impurities may be present with both isolation methods. NanoLC-MS can detect disease biomarkers in exosomes and is useful for critical assessment of exosome enrichment procedures.

High-Performance Chemical Isotope Labeling Liquid Chromatography Mass Spectrometry for Exosome Metabolomics

Circulating exosomes in bodily fluids such as blood are being actively studied as a rich source of chemical biomarkers for cancer diagnosis and monitoring. Although nucleic acid analysis is a primary tool for the discovery of circulating biomarkers in exosomes, metabolomics holds the potential of expanding the chemical diversity of biomarkers that may be easy and rapid to detect. However, only trace amounts of exosomes can be isolated from a small volume of patient blood, and thus a very sensitive technique is required to analyze the metabolome of exosomes. In this report, we present a workflow that involves multiple cycles of ultracentrifugation for exosome isolation using a starting material of 2 mL of human serum, freeze-thaw-cycles in 50% methanol/water for exosome lysis and metabolite extraction, differential chemical isotope labeling (CIL) of metabolites for enhancing liquid chromatography (LC) separation and improving mass spectrometry (MS) detection, and nanoflow LC-MS (nLC-MS) with captivespray for analysis. As a proof-of-principle, we used dansylation labeling to analyze the amine- and phenol-submetabolomes in two sets of exosome samples isolated from the blood samples of five pancreatic cancer patients before and after chemotherapy treatment. The average number of peak pairs or metabolites detected was 1964 ± 60 per sample for a total of 2446 peak pairs ( n = 10) in the first set and 1948 ± 117 per sample for a total of 2511 peak pairs ( n = 10) in the second set. There were 101 and 94 metabolites positively identified in the first and second set, respectively, and 1580 and 1590 peak pairs with accurate masses matching those of metabolites in the MyCompoundID metabolome database. Analyzing the mixtures of 12C-labeled individual exosome samples spiked with a 13C-labeled pooled sample which served as an internal standard allowed relative quantification of metabolomic changes of exosomes of blood samples collected before and after treatment.

Roles of Extracellular Vesicles in Metastatic Breast Cancer

Cells can secrete extracellular vesicles (EVs) to communicate with neighboring or distant cells by EVs which are composed of a lipid bilayer containing transmembrane proteins and enclosing cytosolic proteins, lipids, and nucleic acids. Breast Cancer is the most frequently diagnosed malignancy with more than 1 million new cases each year and ranks the leading cause of cancer mortality in women worldwide. In this review, we will discuss recent progresses of the roles and mechanisms of cancer-derived EVs in metastatic breast cancer, with a special attention on tumor microenvironment construction, progression, and chemo/radiotherapy responses. This review also covers EV roles as biomarker and therapeutic target in clinical application.

The Origin and Functions of Exosomes in Cancer

Exosomes are nanovesicles having a maximum size of 150 nm and is a newly emerging focus in various fields of research. Its role in cargo trafficking along with its differential expression is associated with the disrupted homeostasis and provides an opportunity to defend against different diseases like cancer. Furthermore, exosomes are rich in cargos, which contain proteins and nucleic acids that directly reflect the metabolic state of the cells from which it originates. This review summarizes recent studies on tumor-derived exosomes with an overview about biogenesis, their functions and potential of using as diagnostic and prognostic markers. We also discussed the current challenges and microfluidic-based detection approaches that might improve the detection of exosomes in different settings. More intricate studies of the molecular mechanisms in angiogenesis, pre-metastatic niche formation, and metastasis can give more promising insights and novel strategies in oncotherapeutics.

Tumor-derived exosomes: Potential biomarker or therapeutic target in breast cancer?

Exosomes are released by normal and tumour cells, including those involved in breast cancer, and provide a means of intercellular communications. Exosomes with diameters ranging between 30-150 nm are involved in transferring biological information, via various lipids, proteins, different forms of RNAs, and DNA from one cell to another, and this can result in reprogramming of recipient cell functions. These vesicles are present in all body fluids, for example, blood plasma/serum, semen, saliva, cerebrospinal fluid, breast milk, and urine. It has been recently reported that these particles are involved in the development and progression of different tumor types, including breast cancer. Furthermore, it has been suggested that exosomes have the potential to be used as drug transporters, or as biomarkers. This review highlights the potential roles of exosomes in normal and breast cancer cells and their potential applications as biomarkers with special focus on their potential applications in treatment of breast cancer.

An update on oxysterol biochemistry: New discoveries in lipidomics

Oxysterols are oxidised derivatives of cholesterol or its precursors post lanosterol. They are intermediates in the biosynthesis of bile acids, steroid hormones and 1,25-dihydroxyvitamin D_3. Although often considered as metabolic intermediates there is a growing body of evidence that many oxysterols are bioactive and their absence or excess may be part of the cause of a disease phenotype. Using global lipidomics approaches oxysterols are underrepresented encouraging the development of targeted approaches. In this article, we discuss recent discoveries important in oxysterol biochemistry and some of the targeted lipidomic approaches used to make these discoveries.

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Oxysterols can regulate both the innate and adaptive immune systems.

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Oxysterols can be tumour suppressors and on cometabolites.

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Oxysterols can inhibit or activate the Hh signalling pathway.

Isolation of anti-extra-cellular vesicle single-domain antibodies by direct panning on vesicle-enriched fractions

Background

The thorough understanding of the physiological and pathological processes mediated by extracellular vesicles (EVs) is challenged by purification methods which are cumbersome, not reproducible, or insufficient to yield homogeneous material. Chromatography based on both ion-exchange and immune-capture can represent an effective method to improve EV purification and successive analysis.

Methods

Cell culture supernatant was used as a model sample for assessing the capacity of anion-exchange chromatography to separate distinct EV fractions and to isolate nanobodies by direct panning on whole EVs to recover binders specific for the native conformation of EV-surface epitopes and suitable to develop EV immune-capture reagents.

Results

Anion-exchange chromatography of cell culture supernatant separated distinct protein-containing fractions and all of them were positive for CD9, a biomarker associated to some EVs. This suggested the existence of several EV fractions but did not help in separating EVs from other contaminants. We further isolated several nanobodies instrumental for implementing immune-affinity protocols. These were able to immobilize EVs from both cell culture supernatant and biological samples, to be used in ELISA, flow-cytometry, and immune-purification.

Conclusions

Here we report the first successful isolation of anti-EV nanobodies for the use in immunoaffinity-based EV capture by panning a phage library directly on partially purified EVs. This achievement paves the way for the application of direct EV panning for the discovery of novel antibody-vesicle surface biomarker pairs and represents the preliminary requirement for the development of selective immune-capture that, in combination with anion-exchange chromatography, can simplify the systematic stratification of EV sub-populations and their individual characterization.

Electronic supplementary material

The online version of this article (10.1186/s12934-017-0856-9) contains supplementary material, which is available to authorized users.