Tumor-derived exosomes: A message delivery system for tumor progression

Extracellular vesicle cross-talk in the bone marrow microenvironment: implications in multiple myeloma

The bone marrow (BM) represents a complex microenvironment containing stromal cells, immune cells, osteoclasts, osteoblasts, and hematopoietic cells, which are crucial for the immune response, bone formation, and hematopoiesis. Apart from soluble factors and direct cell-cell contact, extracellular vesicles (EVs), including exosomes, were recently identified as a third mediator for cell communication. Solid evidence has already demonstrated the involvement of various BM-derived cells and soluble factors in the regulation of multiple biological processes whereas the EV-mediated message delivery system from the BM has just been explored in recent decades. These EVs not only perform physiological functions but can also play a role in cancer development, including in Multiple Myeloma (MM) which is a plasma cell malignancy predominantly localized in the BM. This review will therefore focus on the multiple functions of EVs derived from BM cells, the manipulation of the BM by cancer-derived EVs, and the role of BM EVs in MM progression.

CD44/CD44v6 a Reliable Companion in Cancer-Initiating Cell Maintenance and Tumor Progression

Metastasis is the leading cause of cancer death, tumor progression proceeding through emigration from the primary tumor, gaining access to the circulation, leaving the circulation, settling in distant organs and growing in the foreign environment. The capacity of a tumor to metastasize relies on a small subpopulation of cells in the primary tumor, so called cancer-initiating cells (CIC). CIC are characterized by sets of markers, mostly membrane anchored adhesion molecules, CD44v6 being the most frequently recovered marker. Knockdown and knockout models accompanied by loss of tumor progression despite unaltered primary tumor growth unraveled that these markers are indispensable for CIC. The unexpected contribution of marker molecules to CIC-related activities prompted research on underlying molecular mechanisms. This review outlines the contribution of CD44, particularly CD44v6 to CIC activities. A first focus is given to the impact of CD44/CD44v6 to inherent CIC features, including the crosstalk with the niche, apoptosis-resistance, and epithelial mesenchymal transition. Following the steps of the metastatic cascade, we report on supporting activities of CD44/CD44v6 in migration and invasion. These CD44/CD44v6 activities rely on the association with membrane-integrated and cytosolic signaling molecules and proteases and transcriptional regulation. They are not restricted to, but most pronounced in CIC and are tightly regulated by feedback loops. Finally, we discuss on the engagement of CD44/CD44v6 in exosome biogenesis, loading and delivery. exosomes being the main acteurs in the long-distance crosstalk of CIC with the host. In brief, by supporting the communication with the niche and promoting apoptosis resistance CD44/CD44v6 plays an important role in CIC maintenance. The multifaceted interplay between CD44/CD44v6, signal transducing molecules and proteases facilitates the metastasizing tumor cell journey through the body. By its engagement in exosome biogenesis CD44/CD44v6 contributes to disseminated tumor cell settlement and growth in distant organs. Thus, CD44/CD44v6 likely is the most central CIC biomarker.

Biomarker discovery for renal cancer stem cells

Characterised by high intra- and inter-tumor heterogeneity, metastatic renal cell carcinoma (RCC) is resistant to chemo- and radiotherapy. Therefore, the development of new prognostic and diagnostic markers for RCC patients is needed. Cancer stem cells (CSCs) are a small population of neoplastic cells within a tumor which present characteristics reminiscent of normal stem cells. CSCs are characterised by unlimited cell division, maintenance of the stem cell pool (self-renewal), and capability to give rise to all cell types within a tumor; and contribute to metastasis in vivo (tumourigenicity), treatment resistance and recurrence. So far, many studies have tried to establish unique biomarkers to identify CSC populations in RCC. At the same time, different approaches have been developed with the aim to isolate CSCs. Consequently, several markers were found to be specifically expressed in CSCs and cancer stem-like cells derived from RCC such as CD105, ALDH1, OCT4, CD133, and CXCR4. However, the contribution of genetic and epigenetic mechanisms, and tumor microenvironment, to cellular plasticity have made the discovery of unique biomarkers a very difficult task. In fact, contrasting results regarding the applicability of such markers to the isolation of renal CSCs have been reported in the literature. Therefore, a better understanding of the mechanism underlying CSC may help dissecting tumor heterogeneity and drug treatment efficiency.

The effect of tumor-derived exosomes on immune regulation and cancer immunotherapy

Tumor-derived exosomes (TEX) carry both immunosuppressive and immunostimulatory receptor/ligands that in part mimic the profiles of the parent tumor cells. Operating as an intercellular communication system, TEX deliver protumor or antitumor signals to immune and nonimmune cells reprogramming their functions. Mechanisms responsible for cellular reprogramming include cell surface signaling and/or uptake of TEX by recipient cells. Once internalized, TEX transfer mRNA, miRNA and proteins that promote transcriptional/translational activities. TEX-mediated signaling is contextual and, in the tumor microenvironment, TEX largely mediate suppression. TEX may interfere with immune therapies either by sequestration of therapeutic antibodies or elimination of vaccine-induced or adoptively-transferred immune effector cells. TEX are emerging as an ubiquitous subcellular system regulating immune responses in patients with cancer.

Natural extracellular nanovesicles and photodynamic molecules: is there a future for drug delivery?

Photodynamic molecules represent an alternative approach for cancer therapy for their property (i) to be photo-reactive; (ii) to be not-toxic for target cells in absence of light; (iii) to accumulate specifically into tumour tissues; (iv) to be activable by a light beam only at the tumour site and (v) to exert cytotoxic activity against tumour cells. However, to date their clinical use is limited by the side effects elicited by systemic administration. Extracellular vesicles are endogenous nanosized-carriers that have been recently introduced as a natural delivery system for therapeutic molecules. We have recently shown the ability of human exosomes to deliver photodynamic molecules. Therefore, this review focussed on extracellular vesicles as a novel strategy for the delivery of photodynamic molecules at cancer sites. This completely new approach may enhance the delivery and decrease the toxicity of photodynamic molecules, therefore, represent the future for photodynamic therapy for cancer treatment.

DNM3, p65 and p53 from exosomes represent potential clinical diagnosis markers for glioblastoma multiforme

Background:

Glioblastoma multiforme (GBM) is the most aggressive and deadly primary brain cancer that arises from astrocytes and classified as grade IV. Recently, exosomes have been reported as an essential mediator in diverse cancer carcinogenesis and metastasis. However, their role in GBM is still unclear. In this study, we aimed to investigate whether blood exosomes can be potential clinical diagnostic markers for GBM.

Methods:

We used a xenograft orthotopic mouse model to detect the differentially expressed genes in the brain and blood exosomes of original/recurrent GBM.

Results:

We found that recurrent GBM had stronger growth capacity and lethality than original GBM in the mouse model. A gene microarray of original tumors and blood exosomes from GBM orthotopic xenografts results showed that DNM3, p65 and CD117 expressions increased, whereas PTEN and p53 expressions decreased in both original tumors and blood exosomes. In the recurrent GBM tumor model, DNM3 and p65 showed increased expressions, whereas ST14 and p53 showed decreased expressions in tumor and blood exosomes of the recurrent GBM mouse model.

Conclusion:

In summary, we found that DNM3, p65 and p53 had a similar trend in brain and blood exosomes both for original and recurrent GBM, and could serve as potential clinical diagnostic markers for GBM.

Recent advances in exosome-based nanovehicles as RNA interference therapeutic carriers

RNA interference (RNAi) therapeutics (siRNA, miRNA, etc.) represent an emerging medicinal remedy for a variety of ailments. However, their low serum stability and low cellular uptake significantly restrict their clinical applications. Exosomes are biologically derived nanodimensional vesicle ranging from a few nanometers to a hundred. In the last few years, several reports have been published demonstrating the emerging applications of these exogenous membrane vesicles, particularly in carrying different RNAi therapeutics to adjacent or distant targeted cells. In this report, we explored the numerous aspects of exosomes from structure to clinical implications with special emphasis on their application in delivering RNAi-based therapeutics. siRNA and miRNA have attracted great interest in recent years due to their specific application in treating many complex diseases including cancer. We highlight strategies to obviate the challenges of their low bioavailability for gene therapy.

S100-A9 protein in exosomes from chronic lymphocytic leukemia cells promotes NF-κB activity during disease progression

Plasma-derived exosomes from patients with CLL exhibit different protein cargo compositions depending on disease status and progression. S100-A9 protein is overexpressed and S100-A9 cargo in exosomes activates NF-κB pathway in patients with CLL during disease progression.

Heparanase: Potential roles in multiple sclerosis

Heparanase is a heparan sulfate degrading enzyme that cleaves heparan sulfate (HS) chains present on HS proteoglycans (HSPGs), and has been well characterized for its roles in tumor metastasis and inflammation. However, heparanase is emerging as a contributing factor in the genesis and severity of a variety of neurodegenerative diseases and conditions. This is in part due to the wide variety of HSPGs on which the presence or absence of HS moieties dictates protein function. This includes growth factors, chemokines, cytokines, as well as components of the extracellular matrix (ECM) which in turn regulate leukocyte infiltration into the CNS. Roles for heparanase in stroke, Alzheimer's disease, and glioma growth have been described; roles for heparanase in other disease such as multiple sclerosis (MS) are less well established. However, given its known roles in inflammation and leukocyte infiltration, it is likely that heparanase also contributes to MS pathology. In this review, we will briefly summarize what is known about heparanase roles in the CNS, and speculate as to its potential role in regulating disease progression in MS and its animal model EAE (experimental autoimmune encephalitis), which may justify testing of heparanase inhibitors for MS treatment.

Exosomes carrying immunoinhibitory proteins and their role in cancer

Recent emergence of exosomes as information carriers between cells has introduced us to a new previously unknown biological communication system. Multi-directional cross-talk mediated by exosomes carrying proteins, lipids and nucleic acids between normal cells, cells harbouring a pathogen or cancer and immune cells has been instrumental in determining outcomes of physiological as well as pathological conditions. Exosomes play a key role in the broad spectrum of human diseases. In cancer, tumour-derived exosomes carry multiple immunoinhibitory signals, disable anti-tumour immune effector cells and promote tumour escape from immune control. Exosomes delivering negative signals to immune cells in cancer, viral infections, autoimmune or other diseases may interfere with therapy and influence outcome. Exosomes can activate tissue cells to produce inhibitory factors and thus can suppress the host immune responses indirectly. Exosomes also promise to be non-invasive disease biomarkers with a dual capability to provide insights into immune dysfunction as well as disease progression and outcome.

Targeting adenosine in cancer immunotherapy: a review of recent progress

INTRODUCTION

The adenosine pathway plays a key role in modulating immune responses in health and in disease. In health, anti-inflammatory effects of adenosine balance pro-inflammatory ATP, limiting tissue destruction by activated immune cells. In disease, this balance is disturbed. Areas covered: This review focuses on cancer and explains how in the microenvironment, the ATP-adenosine balance shifts towards an excess of extracellular adenosine Expert commentary: The CD73-adenosine axis plays a key role in the inhibition of anti-tumor functions of immune effector cells. Today, adenosine emerges as one of the immune checkpoints that are implicated in the tumor escape from the host immune system. The adenosine pathway is currently viewed as a significant barrier to the effectiveness of immune therapies and becomes an important therapeutic target in cancer. Pharmacologic inhibitors or antibodies specific for the components of the adenosine pathways or adenosine receptors show efficacy in pre-clinical studies and are entering the clinical arena.

Clinical application of a microfluidic chip for immunocapture and quantification of circulating exosomes to assist breast cancer diagnosis and molecular classification

Increasing attention has been attracted by exosomes in blood-based diagnosis because cancer cells release more exosomes in serum than normal cells and these exosomes overexpress a certain number of cancer-related biomarkers. However, capture and biomarker analysis of exosomes for clinical application are technically challenging. In this study, we developed a microfluidic chip for immunocapture and quantification of circulating exosomes from small sample volume and applied this device in clinical study. Circulating EpCAM-positive exosomes were measured in 6 cases breast cancer patients and 3 healthy controls to assist diagnosis. A significant increase in the EpCAM-positive exosome level in these patients was detected, compared to healthy controls. Furthermore, we quantified circulating HER2-positive exosomes in 19 cases of breast cancer patients for molecular classification. We demonstrated that the exosomal HER2 expression levels were almost consistent with that in tumor tissues assessed by immunohistochemical staining. The microfluidic chip might provide a new platform to assist breast cancer diagnosis and molecular classification.

Exosomes in Cancer: Another Mechanism of Tumor-Induced Immune Suppression

Exosomes are the smallest extracellular vesicles (EV) produced under physiological and pathological conditions by all cells and present in all body fluids. They are critical components of the intercellular communication network. Tumor cells release exosomes which are enriched in immunosuppressive molecules as well as biologically-active soluble factors and enzymes. Tumor-derived exosomes (TEX) interact with immune effector cells in the tumor microenvironment and in the circulation, deliver negative signals to these cells and interfere with their anti-tumor functions. By suppressing functions of immune effector cells, TEX promote tumor progression and facilitate tumor escape from the immune system. Thus, TEX can be viewed as immune checkpoint inhibitors. Silencing of TEX-mediated immune inhibition without disrupting the physiologically important cellular communication networks represents a considerable challenge. Current efforts are directed at achieving a better understanding of the role exosomes play in cancer progression and/or outcome and of molecular/genetic mechanisms responsible for immunoinhibitory activity of TEX.

MicroRNAs contribution in tumor microenvironment of esophageal cancer

BACKGROUND

miRNAs have recently been implicated in tumor's microenvironment remodeling and tumor-stromal cells interactions. We have previously reported a signaling role for miR-21, as a secretory molecule released by cancer associated fibroblasts (CAF) adjacent to esophagus tumor cells.

OBJECTIVE

To discover other potential signaling miRNAs, we employed a co-culture system of esophageal cancer cell line and normal fibroblasts to mimic the tumor microenvironment.

METHODS

We measured the expression profile of secretory miRNAs in the conditioned media (CM) of our co-culture system using a panel PCR array. We used pathway enrichment analysis to define potential pathways regulated by these miRNAs. Then using ultracentrifugation, we purified exosomes secreted to the CM of co-cultured cell lines and evaluated exosomal secretion of these miRNAs.

RESULTS

We found 18 miRNAs which were significantly up/down-regulated in the CM of co-culture system. Pathways related to cell adhesion, endocytosis and cell junctions were among the enriched pathways that might be related to CAF phenotype and tumor progression. Moreover, we detected higher exosomal levels of miR-33a and miR-326 in the purified exosomes both in co-cultured and untreated CM. So, these miRNAs are mainly secreted into the CM by means of exosomes.

CONCLUSIONS

Briefly, our data shed more light on the role of CAFs through secretion of miRNAs within tumor microenvironment and propose novel therapeutic targets for esophageal and probably other cancer types.

Tumor-Derived Exosomes and Their Role in Tumor-Induced Immune Suppression

Tumor-derived exosomes (TEX) are emerging as critical components of an intercellular information network between the tumor and the host. The tumor escapes from the host immune system by using a variety of mechanisms designed to impair or eliminate anti-tumor immunity. TEX carrying a cargo of immunoinhibitory molecules and factors represent one such mechanism. TEX, which are present in all body fluids of cancer patients, deliver negative molecular or genetic signals to immune cells re-programming their functions. Although TEX can also stimulate immune activity, in the microenvironments dominated by the tumor, TEX tend to mediate immune suppression thus promoting tumor progression. The TEX content, in part resembling that of the parent cell, may serve as a source of cancer biomarkers. TEX also interfere with immune therapies. A better understanding of TEX and their contribution to cancer progression and cancer patients’ response to immune therapies represents a challenging new field of investigation.

Exosomes derived from HCC cells induce sorafenib resistance in hepatocellular carcinoma both in vivo and in vitro

Background

Exosomes are carriers of intercellular information and regulate the tumor microenvironment. They play an important role in drug resistance by transporting RNA molecules and proteins. However, their effects on sorafenib resistance in hepatocellular carcinoma (HCC) are not completely understood.

Methods

Exosomes were isolated from two invasive hepatoma cell lines (MHCC-97 L and MHCC-97H), and their roles in regulating sorafenib resistance in liver cancer cells as well as the underlying molecular mechanisms were determined. The exosomes were analyzed by TEM (transmission electron microscopy), DLS (dynamic light scattering) and Western blotting. Cell viability, cell death and the effects of exosomes on the HGF/c-Met/Akt signaling pathway in cancer cells were analyzed by MTT assays, FACS analysis and Western blotting, respectively. Moreover, the effects of exosomes on sorafenib resistance in vivo were investigated using a subcutaneous transplantation tumor model in athymic nude mice.

Results

Exosomes derived from HCC cells were of the expected size and expressed the exosomal markers CD9 and CD63. They induced sorafenib resistance in vitro by activating the HGF/c-Met/Akt signaling pathway and inhibiting sorafenib-induced apoptosis. They also induced sorafenib resistance in vivo by inhibiting sorafenib-induced apoptosis. Moreover, exosomes derived from highly invasive tumor cells had greater efficacy than that of exosomes derived from less invasive cells.

Conclusions

These data reveal the important role of HCC cell-derived exosomes in the drug resistance of liver cancer cells and demonstrate the intrinsic interaction between exosomes and their targeted tumor cells. This study suggests a new strategy for improving the effectiveness of sorafenib in treating HCC.

Proteomic Analysis of Exosomes and Exosome-Free Conditioned Media From Human Osteosarcoma Cell Lines Reveals Secretion of Proteins Related to Tumor Progression

Osteosarcomas are the most prevalent bone tumors in pediatric patients, but can also occur later in life. Bone tumors have the potential to metastasize to lung and occasionally other vital organs. To understand how osteosarcoma cells interact with their micro-environment to support bone tumor progression and metastasis, we analyzed secreted proteins and exosomes from three human osteosarcoma cell lines. Exosome isolation was validated by transmission electron microscopy (TEM) and immuno-blotting for characteristic biomarkers (CD63, CD9, and CD81). Exosomal and soluble proteins (less than 100 kDa) were identified by mass spectrometry analysis using nanoLC-MS/MS and classified by functional gene ontology clustering. We identified a secretome set of >3,000 proteins for both fractions, and detected proteins that are either common or unique among the three osteosarcoma cell lines. Protein ontology comparison of proteomes from exosomes and exosome-free fractions revealed differences in the enrichment of functional categories associated with different biological processes, including those related to tumor progression (i.e., angiogenesis, cell adhesion, and cell migration). The secretome characteristics of osteosarcoma cells are consistent with the pathological properties of tumor cells with metastatic potential. J. Cell. Biochem. 118: 351-360, 2017. © 2016 Wiley Periodicals, Inc.

Extracellular vesicle microRNAs mediate skeletal muscle myogenesis and disease

Skeletal muscle function is important for good health and independent living, and has been subject to numerous studies focused on skeletal muscle development, function and metabolism. However, progressive and degenerative changes in skeletal muscle function often occur following physiological and pathological stress, and these lead to the progression of diabetes, obesity, chronic kidney disease, and cardiovascular or respiratory diseases. Identifying the mechanisms that influence the processes regulating skeletal muscle function is a key priority. Recently, studies have demonstrated that microRNAs (miRNAs) play important roles in regulating biological processes. For instance, exosomes are key tools for communication between cells. Therefore, by determining how select miRNAs are transported to target organs and initiate their effects, these results will help explain muscle and organ crosstalk, improve our understanding and application of current therapeutic approaches and lead to the identification of new therapeutic strategies and targets aimed at maintaining and/or improving skeletal muscle health.

Plasma-derived exosomes in acute myeloid leukemia for detection of minimal residual disease: are we ready?

The recent emergence of plasma-derived exosomes as biomarkers of leukemic relapse has introduced the potential for more sensitive non-invasive monitoring of leukemia patients based on the molecular and genetic analysis of the exosome cargo. In principle, the protein, lipid, miRNA, mRNA or DNA profiles of exosomes in patients' plasma that associate with leukemic relapse can be identified. The diagnostic/prognostic value of these profiles could then be validated in prospective clinical studies. Here, we consider the potential of exosomes to fulfill the role of future biomarkers of minimal residual disease in AML. The rationale for developing exosome-based methodology for minimal residual disease detection is based on promising early observations. However, standards need to be established for evaluating exosome identity, isolation from body fluids, and assessment methods. The rapidly expanding knowledge of the exosome biology suggests that the exosome status as potential biomarkers may become clarified in the near future.

Tumor-Derived Exosomes and Their Role in Cancer Progression

Tumor cells actively produce, release, and utilize exosomes to promote tumor growth. Mechanisms through which tumor-derived exosomes subserve the tumor are under intense investigation. These exosomes are information carriers, conveying molecular and genetic messages from tumor cells to normal or other abnormal cells residing at close or distant sites. Tumor-derived exosomes are found in all body fluids. Upon contact with target cells, they alter phenotypic and functional attributes of recipients, reprogramming them into active contributors to angiogenesis, thrombosis, metastasis, and immunosuppression. Exosomes produced by tumors carry cargos that in part mimic contents of parent cells and are of potential interest as noninvasive biomarkers of cancer. Their role in inhibiting the host antitumor responses and in mediating drug resistance is important for cancer therapy. Tumor-derived exosomes may interfere with cancer immunotherapy, but they also could serve as adjuvants and antigenic components of antitumor vaccines. Their biological roles in cancer development or progression as well as cancer therapy suggest that tumor-derived exosomes are critical components of oncogenic transformation.

High-efficiency Generation of Multiple Short Noncoding RNA in B-cells and B-cell-derived Extracellular Vesicles

Short noncoding (snc)RNAs are important new players in the landscape of biologics with therapeutic potential. Recently, we reported on a new method for the synthesis and delivery of snc RNA in B-cells transfected with plasmid DNA. Here using the same approach, we demonstrate that B-cells can be programmed for the enforced biogenesis and synchronous release of multiple sncRNAs. Our data show that this goal is feasible and that multiple sncRNA are released in the extracellular compartment in amounts comparable to those from B-cells programmed to express and secrete one scnRNA only. Furthermore, we found that the cargo of extracellular vescicles (EVs) isolated from programmed B-cells is remarkably enriched for multiple sncRNA. On average, we found that the content of multiple sncRNAs in EVs is 3.6 copynumber/EV. Collectively, we demonstrate that B-cells can be easily programmed toward the synthesis and release of multiple sncRNAs, including sncRNA-laden EVs, efficiently and specifically.

Claudin-7 promotes the epithelial-mesenchymal transition in human colorectal cancer

In colorectal cancer (CoCa) EpCAM is frequently associated with claudin-7. There is evidence that tumor-promoting EpCAM activities are modulated by the association with claudin-7. To support this hypothesis, claudin-7 was knocked-down (kd) in HT29 and SW948 cells.

HT29-cld7^kd and SW948-cld7^kd cells display decreased anchorage-independent growth and the capacity for holoclone-, respectively, sphere-formation is reduced. Tumor growth is delayed and cld7^kd cells poorly metastasize. In line with this, migratory and invasive potential of cld7^kd clones is strongly impaired, migration being inhibited by anti-CD49c, but not anti-EpCAM, although motility is reduced in EpCAM siRNA-treated cells. This is due to claudin-7 recruiting EpCAM in glycolipid-enriched membrane fractions towards claudin-7-associated TACE and presenilin2, which cleave EpCAM. The cleaved intracellular domain, EpIC, promotes epithelial-mesenchymal transition (EMT)-associated transcription factor expression, which together with fibronectin and vimentin are reduced in claudin-7^kd cells. But, uptake of HT29^wt and SW948^wt exosomes by the claudin-7^kd lines sufficed for transcription factor upregulation and for restoring motility.

Thus, claudin-7 contributes to motility and invasion and is required for recruiting EpCAM towards TACE/presenilin2. EpIC generation further supports motility by promoting a shift towards EMT. Notably, EMT features of cld7-competent metastatic CoCa cells can be transferred via exosomes to poorly metastatic cells.

Adjuvant for vaccine immunotherapy of cancer--focusing on Toll-like receptor 2 and 3 agonists for safely enhancing antitumor immunity

Immune‐enhancing adjuvants usually targets antigen (Ag)‐presenting cells to tune up cellular and humoral immunity. CD141⁺ dendritic cells (DC) represent the professional Ag‐presenting cells in humans. In response to microbial pattern molecules, these DCs upgrade the maturation stage sufficient to improve cross‐presentation of exogenous Ag, and upregulation of MHC and costimulators, allowing CD4/CD8 T cells to proliferate and liberating cytokines/chemokines that support lymphocyte attraction and survival. These DCs also facilitate natural killer‐mediated cell damage. Toll‐like receptors (TLRs) and their signaling pathways in DCs play a pivotal role in DC maturation. Therefore, providing adjuvants in addition to Ag is indispensable for successful vaccine immunotherapy for cancer, which has been approved in comparison with antimicrobial vaccines. Mouse CD8α⁺DCs express TLR7 and TLR9 in addition to the TLR2 family (TLR1, 2, and 6) and TLR3, whereas human CD141⁺DCs exclusively express the TLR2 family and TLR3. Although human and mouse plasmacytoid DCs commonly express TLR7/9 to respond to their agonists, the results on mouse adjuvant studies using TLR7/9 agonists cannot be simply extrapolated to human adjuvant immunotherapy. In contrast, TLR2 and TLR3 are similarly expressed in both human and mouse Ag‐presenting DCs. Bacillus Calmette–Guerin peptidoglycan and polyinosinic–polycytidylic acid are representative agonists for TLR2 and TLR3, respectively, although they additionally stimulate cytoplasmic sensors: their functional specificities may not be limited to the relevant TLRs. These adjuvants have been posted up to a certain achievement in immunotherapy in some cancers. We herein summarize the history and perspectives of TLR2 and TLR3 agonists in vaccine‐adjuvant immunotherapy for cancer.

The potential of tumor-derived exosomes for noninvasive cancer monitoring

Tumor-derived exosomes (TEX) are emerging as a new type of cancer biomarker. TEX are membrane-bound, virus-size vesicles of endocytic origin present in all body fluids of cancer patients. Based on the expanding albeit incomplete knowledge of their biogenesis, secretion by tumor cells and cancer cell-specific molecular and genetic contents, TEX are viewed as promising, clinically-relevant surrogates of cancer progression and response to therapy. Preliminary proteomic, genetic and functional profiling of tumor cell-derived or cancer plasma-derived exosomes confirms their unique characteristics. Alterations in protein or nucleic acid profiles of exosomes in plasma of cancer patients responding to therapies appear to correlate with clinical endpoints. However, methods for TEX isolation and separation from the bulk of human plasma-derived exosomes are not yet established and their role as biomarkers remains to be confirmed. Further development and validation of TEX as noninvasive, liquid equivalents of tumor biopsies are necessary to move this effort forward.

Curcumin Modulates Pancreatic Adenocarcinoma Cell-Derived Exosomal Function

Pancreatic cancer has the highest mortality rates of all cancer types. One potential explanation for the aggressiveness of this disease is that cancer cells have been found to communicate with one another using membrane-bound vesicles known as exosomes. These exosomes carry pro-survival molecules and increase the proliferation, survival, and metastatic potential of recipient cells, suggesting that tumor-derived exosomes are powerful drivers of tumor progression. Thus, to successfully address and eradicate pancreatic cancer, it is imperative to develop therapeutic strategies that neutralize cancer cells and exosomes simultaneously. Curcumin, a turmeric root derivative, has been shown to have potent anti-cancer and anti-inflammatory effects in vitro and in vivo. Recent studies have suggested that exosomal curcumin exerts anti-inflammatory properties on recipient cells. However, curcumin's effects on exosomal pro-tumor function have yet to be determined. We hypothesize that curcumin will alter the pro-survival role of exosomes from pancreatic cancer cells toward a pro-death role, resulting in reduced cell viability of recipient pancreatic cancer cells. The main objective of this study was to determine the functional alterations of exosomes released by pancreatic cancer cells exposed to curcumin compared to exosomes from untreated pancreatic cancer cells. We demonstrate, using an in vitro cell culture model involving pancreatic adenocarcinoma cell lines PANC-1 and MIA PaCa-2, that curcumin is incorporated into exosomes isolated from curcumin-treated pancreatic cancer cells as observed by spectral studies and fluorescence microscopy. Furthermore, curcumin is delivered to recipient pancreatic cancer cells via exosomes, promoting cytotoxicity as demonstrated by Hoffman modulation contrast microscopy as well as AlamarBlue and Trypan blue exclusion assays. Collectively, these data suggest that the efficacy of curcumin may be enhanced in pancreatic cancer cells through exosomal facilitation.

Radionuclide Therapy of Unresectable Tumors with AvidinOX and (90)Y-biotinDOTA: Tongue Cancer Paradigm

Local treatment of unresectable tumors is challenging, particularly with radioactivity. Current practice relies on external beam irradiation or on a variety of medical devices for brachytherapy. Both approaches proved useful in controlling tumor growth, but are characterized by poor compliance of the patient, significant side-effects, high costs, and technological complexity, which hamper widespread use. The authors recently described a novel form of radionuclide therapy based on the oxidized form of avidin that, chemically reacting with tissue proteins, can secure radioactive biotin within the injected tissue, either when precomplexed or when taken from the blood stream after intravenous administration. AvidinOX-pretargeted ¹⁷⁷Lu-biotinDOTA (¹⁷⁷Lu-ST2210) is currently under clinical investigation for the treatment of liver oligometastases from colorectal cancer (clinicaltrials.gov/NCT02053324). In the present work, the authors show that injected AvidinOX can link tissues of various natures such as prostate, kidney, breast, or brain and can react by contact with scraped tissues such as skin or urinary bladder. AvidinOX injected into human OSC19 tongue cancer masses orthotopically transplanted in nude mice takes up intravenously administered ⁹⁰Y-ST2210, which exerts significant antitumor activity, while preserving the integrity and functionality of the tongue. Present data confirm that AvidinOX-based radionuclide therapy is an innovative and promising approach for the local treatment of inoperable tumors.

The mesmiRizing complexity of microRNAs for striated muscle tissue engineering

microRNAs (miRs) are small non-protein-coding RNAs, able to post-transcriptionally regulate many genes and exert pleiotropic effects. Alteration of miR levels in tissues and in the circulation has been associated with various pathological and regenerative conditions. In this regard, tissue engineering of cardiac and skeletal muscles is a fascinating context for harnessing the complexity of miR-based circuitries and signals. In this review, we will focus on miR-driven regulation of cardiac and skeletal myogenic routes in homeostatic and challenging states. Furthermore, we will survey the intriguing perspective of exosomal and circulating miRs as novel paracrine players, potentially useful for current and future approaches of regenerative medicine for the striated muscles.

Tracking miRNAs' footprints in tumor-microenvironment interactions: Insights and implications for targeted cancer therapy

In the past decades, cancer medicine studies have mainly focused on tumor cell biology as the main promoter of solid tumor progression. However, tumor biology does not explain the intertwinement and ambiguity of the tumors' territory. Recently, the approach of understanding cancer has shifted from investigating the biology of tumor cells to studying the microenvironment surrounding them. MicroRNAs (miRNAs), which play a role in exploiting indigenous stromal cells and are components that cooperate and produce a favorable microenvironment for progressive tumor formation, have been implicated in numerous processes essential for tumor initiation and growth. Understanding the mechanisms underlying interactions between tumor cells and their adjacent environment holds many promises for the future of cancer-targeted therapies. Herein, we provide a step-by-step account of miRNA involvement in tumor-microenvironment interactions as the micromediators of tumor cell and stroma communications. We also focus on the clinical challenges in using miRNAs tof overcome therapy resistance mechanisms and tumor heterogeneity bias in cancer therapy.

Immunoglobulin Free Light Chains and GAGs Mediate Multiple Myeloma Extracellular Vesicles Uptake and Secondary NfκB Nuclear Translocation

Multiple myeloma (MM) is a hematological malignancy caused by a microenviromentally aided persistence of plasma cells in the bone marrow. Monoclonal plasma cells often secrete high amounts of immunoglobulin free light chains (FLCs) that could induce tissue damage. Recently, we showed that FLCs are internalized in endothelial and myocardial cell lines and secreted in extracellular vesicles (EVs). MM serum derived EVs presented phenotypic differences if compared with monoclonal gammopathy of undetermined significance (MGUS) serum derived EVs suggesting their involvement in MM pathogenesis or progression. To investigate the effect of circulating EVs on endothelial and myocardial cells, we purified MM and MGUS serum derived EVs with differential ultracentrifugation protocols and tested their biological activity. We found that MM and MGUS EVs induced different proliferation and internalization rates in endothelial and myocardial cells, thus we tried to find specific targets in MM EVs docking and processing. Pre-treatment of EVs with anti-FLCs antibodies or heparin blocked the MM EVs uptake, highlighting that FLCs and glycosaminoglycans are involved. Indeed, only MM EVs exposure induced a strong nuclear factor kappa B nuclear translocation that was completely abolished after anti-FLCs antibodies and heparin pre-treatment. The protein tyrosine kinase c-src is present on MM circulating EVs and redistributes to the cell plasma membrane after MM EVs exposure. The anti-FLCs antibodies and heparin pre-treatments were able to block the intracellular re-distribution of the c-src kinase and the subsequent c-src kinase containing EVs production. Our results open new insights in EVs cellular biology and in MM therapeutic and diagnostic approaches.

Immunotherapeutic potential of extracellular vesicles

Extracellular vesicle or EV is a term that encompasses all classes of secreted lipid membrane vesicles. Despite being scientific novelties, EVs are gaining importance as a mediator of important physiological and pathological intercellular activities possibly through the transfer of their cargo of protein and RNA between cells. In particular, exosomes, the currently best characterized EVs have been notable for their in vitro and in vivo immunomodulatory activities. Exosomes are nanometer-sized endosome-derived vesicles secreted by many cell types and their immunomodulatory potential is independent of their cell source. Besides immune cells such as dendritic cells, macrophages, and T cells, cancer and stem cells also secrete immunologically active exosomes that could influence both physiological and pathological processes. The immunological activities of exosomes affect both innate and adaptive immunity and include antigen presentation, T cell activation, T cell polarization to regulatory T cells, immune suppression, and anti-inflammation. As such, exosomes carry much immunotherapeutic potential as a therapeutic agent and a therapeutic target.

Rapid isolation of extracellular vesicles from cell culture and biological fluids using a synthetic peptide with specific affinity for heat shock proteins

Recent studies indicate that extracellular vesicles are an important source material for many clinical applications, including minimally-invasive disease diagnosis. However, challenges for rapid and simple extracellular vesicle collection have hindered their application. We have developed and validated a novel class of peptides (which we named venceremin, or Vn) that exhibit nucleotide-independent specific affinity for canonical heat shock proteins. The Vn peptides were validated to specifically and efficiently capture HSP-containing extracellular vesicles from cell culture growth media, plasma, and urine by electron microscopy, atomic force microscopy, sequencing of nucleic acid cargo, proteomic profiling, immunoblotting, and nanoparticle tracking analysis. All of these analyses confirmed the material captured by the Vn peptides was comparable to those purified by the standard ultracentrifugation method. We show that the Vn peptides are a useful tool for the rapid isolation of extracellular vesicles using standard laboratory equipment. Moreover, the Vn peptides are adaptable to diverse platforms and therefore represent an excellent solution to the challenge of extracellular vesicle isolation for research and clinical applications.

Exocytosis and Endocytosis of Small Vesicles across the Plasma Membrane in Saccharomyces cerevisiae

When Saccharomyces cerevisiae is starved of glucose, the gluconeogenic enzymes fructose-1,6-bisphosphatase (FBPase), phosphoenolpyruvate carboxykinase, isocitrate lyase, and malate dehydrogenase, as well as the non-gluconeogenic enzymes glyceraldehyde-3-phosphate dehydrogenase and cyclophilin A, are secreted into the periplasm. In the extracellular fraction, these secreted proteins are associated with small vesicles that account for more than 90% of the total number of extracellular structures observed. When glucose is added to glucose-starved cells, FBPase is internalized and associated with clusters of small vesicles in the cytoplasm. Specifically, the internalization of FBPase results in the decline of FBPase and vesicles in the extracellular fraction and their appearance in the cytoplasm. The clearance of extracellular vesicles and vesicle-associated proteins from the extracellular fraction is dependent on the endocytosis gene END3. This internalization is regulated when cells are transferred from low to high glucose. It is rapidly occurring and is a high capacity process, as clusters of vesicles occupy 10%–20% of the total volume in the cytoplasm in glucose re-fed cells. FBPase internalization also requires the VPS34 gene encoding PI3K. Following internalization, FBPase is delivered to the vacuole for degradation, whereas proteins that are not degraded may be recycled.

The Role of Heparanase and Sulfatases in the Modification of Heparan Sulfate Proteoglycans within the Tumor Microenvironment and Opportunities for Novel Cancer Therapeutics

Heparan sulfate proteoglycans (HSPGs) are an integral and dynamic part of normal tissue architecture at the cell surface and within the extracellular matrix. The modification of HSPGs in the tumor microenvironment is known to result not just in structural but also functional consequences, which significantly impact cancer progression. As substrates for the key enzymes sulfatases and heparanase, the modification of HSPGs is typically characterized by the degradation of heparan sulfate (HS) chains/sulfation patterns via the endo-6-O-sulfatases (Sulf1 and Sulf2) or by heparanase, an endo-glycosidase that cleaves the HS polymers releasing smaller fragments from HSPG complexes. Numerous studies have demonstrated how these enzymes actively influence cancer cell proliferation, signaling, invasion, and metastasis. The activity or expression of these enzymes has been reported to be modified in a variety of cancers. Such observations are consistent with the degradation of normal architecture and basement membranes, which are typically compromised in metastatic disease. Moreover, recent studies elucidating the requirements for these proteins in tumor initiation and progression exemplify their importance in the development and progression of cancer. Thus, as the influence of the tumor microenvironment in cancer progression becomes more apparent, the focus on targeting enzymes that degrade HSPGs highlights one approach to maintain normal tissue architecture, inhibit tumor progression, and block metastasis. This review discusses the role of these enzymes in the context of the tumor microenvironment and their promise as therapeutic targets for the treatment of cancer.

Stem cell delivery of therapies for brain disorders

The blood brain barrier (BBB) poses a problem to deliver drugs for brain malignancies and neurodegenerative disorders. Stem cells such as neural stem cells (NSCs) and mesenchymal stem cells (MSCs) can be used to delivery drugs or RNA to the brain. This use of methods to bypass the hurdles of delivering drugs across the BBB is particularly important for diseases with poor prognosis such as glioblastoma multiforme (GBM). Stem cell treatment to deliver drugs to neural tumors is currently in clinical trial. This method, albeit in the early phase, could be an advantage because stem cells can cross the BBB into the brain. MSCs are particularly interesting because to date, the experimental and clinical evidence showed 'no alarm signal' with regards to safety. Additionally, MSCs do not form tumors as other more primitive stem cells such as embryonic stem cells. More importantly, MSCs showed pathotropism by migrating to sites of tissue insult. Due to the ability of MSCs to be transplanted across allogeneic barrier, drug-engineered MSCs can be available as off-the-shelf cells for rapid transplantation. This review discusses the advantages and disadvantages of stem cells to deliver prodrugs, genes and RNA to treat neural disorders.