Skip to content
Events

Extracellular vesicles and the tumour microenvironment

Discussion meeting

Starts:

January
232017

09:00

Ends:

January
242017

17:00

Location

The Royal Society, London, 6-9 Carlton House Terrace, London, SW1Y 5AG

Overview

Scientific discussion meeting organised by Dr Daniel Lambert, Dr Dave Carter, Dr Stuart Hunt, Dr Aled Clayton and Dr Andrew Devitt.

Prostate cancer exosomes (red) being taken up by fibroblasts (bright field / fluor overlay), taken by Alexander Cocks, Cardiff University.

This meeting will explore the fundamental roles that extracellular vesicles can play in cell-to-cell communication, with a specific focus on their role in the tumour microenvironment. The importance of these two areas has emerged in the past decade and this meeting will explore the synergies that exist between the two fields.

The schedule of talks and speaker biographies are available below. Speaker abstracts will be available closer to the meeting date. Recorded audio of the presentations will be available on this page after the meeting has taken place. Meeting papers will be published in a future issue of Philosophical Transactions B.

Attending this event

This meeting is intended for researchers in relevant fields.

  • Free to attend
  • Limited places, advanced registration is essential
  • An optional lunch can be purchased during registration

An evening poster session and drinks reception will be held following the close of the meeting on Monday 23 January. Whilst the posters are free to view for all  registered participants, the corresponding optional drinks reception is ticketed. Drinks tickets can be purchased in advance during registration. 

Enquiries: Contact the Scientific Programmes team

Event organisers

Select an organiser for more information

Schedule of talks

23 January

Chair: Dr Dan Lambert 09:00-12:30

9 talks Show detail Hide detail

Chairs

Dr Dan Lambert, University of Sheffield

09:05-09:30 Tumour extracellular vesicles and breast cancer metastasis

Dr Miki De Palma, École Polytechnique Eédérale de Lausanne

Abstract

In spite of significant improvements in treatments and survival rates, metastatic breast cancer remains one of the leading causes of cancer-related deaths in women worldwide. Taxanes are microtubule-stabilizing agents largely employed as cytotoxic agents for breast cancer treatment, both in the adjuvant and neoadjuvant setting. Increasing evidence suggests that the cancer cells of primary tumors release extracellular vesicles (tEVs), which can facilitate the homing of metastatic cells to target organs. We found that paclitaxel – a lead taxane – enhances tEV release from murine breast cancer cells, both in vitro and in vivo. I will present the functional implications of this phenomenon in the context of breast cancer. Furthermore, I will discuss the determinants of microRNA sorting to EVs, and the significance of EV-mediated microRNA transfer to acceptor cells.

Show speakers

09:30-09:45 Discussion

09:45-10:15 An apoptosis-driven 'onco-regenerative niche': roles of tumour-associated macrophages and extracellular vesicles

Professor Christopher D Gregory, MRC Centre for Inflammation Research

Abstract

Apoptosis is a well-established anti-oncogenic cell-death programme. Paradoxically, high apoptosis indices in tumours are closely coupled with poor prognosis. Indeed, where it has been studied, cell loss is a striking feature of high-grade cancers, illustrating the importance of considering malignant disease as an imbalance between cell gain and cell loss rather than as a unidirectional disorder of cell gain alone. In addition to orchestrating cell loss, apoptosis can signal regenerative responses; for example compensatory proliferation in other cells. Accumulating evidence suggests that normal tissue repair and regenerative processes are hijacked in the malignant tissue microenvironment such that cancer may be likened to a “wound that fails to stop repairing”. 

We have proposed that a critical requirement for the successful growth, progression and re-growth of malignant tumours is a complex niche, conceptually termed the “onco-regenerative niche”, which is composed, in addition to transformed neoplastic cells, of normal cells and factors activated as if in tissue repair and regeneration. Our work is based around the hypothesis that tumour cell apoptosis, macrophage activation and endothelial activation are key, interlinked elements of the onco-regenerative niche and that apoptotic tumour cell-derived extracellular vesicles (Apo-EVs) provide critical intercellular communication vehicles of the niche. In aggressive B-cell lymphoma, tumour cell apoptosis promotes both angiogenesis and the accumulation of pro-tumour macrophages in the lymphoma microenvironment. Furthermore, lymphoma-derived apo-EVs have potent pro-tumour potential. These findings have important implications for the roles of apoptosis in regulation of malignant diseases and for the efficacy of apoptosis-inducing anti-cancer therapies.

Show speakers

10:15-10:30 Discussion

11:00-11:15 Cellular stress sensors mTORC1 switches exosome biogenesis and secretion pathways to influence the tumour microenvironment

Abstract

Contributory talk given by Associate Professor Deborah Goberdhan. 

Cancer cells can adapt to nutrient starvation and growth inhibitory drugs by communicating with their neighbours via secreted soluble factors, exosomes and other extracellular vesicles. Exosomes are commonly believed to originate in late endosomal multivesicular bodies, but the intracellular mechanisms modulating their functions remain poorly characterised. Here a new type of exosome biogenesis pathway involving Rab11-positive recycling endosomes is identified that releases exosomes with enhanced reprogramming activities. This pathway is present in both human cancer cells and an in vivo Drosophila model of exosome secretion. Using the fly model the biogenesis of these different exosome subtypes can be visualised in living tissue for the first time. 

Inhibiting the glutamine-sensing PAT4 amino acid transporter blocks a specific form of mTORC1 signalling, leading to the preferential release of exosomes from recycling endosomes. Functionally, these stress-induced exosomes orchestrate signalling in recipient cells, which promotes pro-tumorigenic microenvironmental changes and cancer growth. Therefore in cancer cells the mTORC1 signalling hub senses microenvironmental stresses and then modulates exosome secretory pathways to drive tumour adaptation. These findings may partly explain why mTORC1 inhibitors often have poor clinical efficacy, and highlight the importance of distinguishing exosomal sub-types when defining their effects on the tumour microenvironment.

11:15-11:30 Tetherin exosomes

Abstract

Contributory talk given by James Edgar

Edgar et al demonstrate that exosome release can be induced in HeLa cells upon inhibition of the V-ATPase, and that exosomes are observed in clusters at the plasma membrane. Such clustering shows striking similarities to clusters of retroviruses, which are attached to the plasma membrane by tetherin. To determine whether tetherin also attaches exosomes, it was knocked out and this resulted in a 4-fold reduction in plasma membrane-associated exosomes, with a concomitant increase in exosomes discharged into the medium. Such phenotype could be rescued by expression of wild-type tetherin but not tetherin lacking its GPI anchor. Edgar et al propose that tetherin may play a key role in exosome fate, determining whether they participate in long-range or short-range interactions.

11:30-11:45 Discussion

11:45-12:15 Can glioblastoma extracellular vesicles drive normal astrocytes towards a tumour-enhancing phenotype?

Dr Michael Graner, University of Colorado Denver

Abstract

Glioblastomas (GBMs, WHO grade IV astrocytomas) are the worst of the central nervous system tumors; despite maximum (and damaging) therapeutic intervention, median survival time for patients is <15 months, and overall quality of life is poor. These abysmal outcomes have changed little in 20 years. Clearly, our current therapies are inadequate; we need innovative strides in understanding GBM biology to rectify this situation. One “hot” research area is that of the impact of tumor extracellular vesicles (EVs) on normal recipient cells. Tumor EVs have extraordinary abilities to manipulate tumor microenvironments and recipient cells both proximally and distally. Tumor EVs prepare the “metastatic niche” for circulating tumor cells prior to colonization of a target organ, deflect immune responses, and alter normal cells. Thus, tumor EVs impact recipient cells to support tumor growth and progression, which undoubtedly holds true for GBMs as well. However, little is known about effects of GBM EVs on normal astrocytes—do GBM EVs drive astrocyte phenotypic changes, potentially making the astrocytes into tumor promotors? The answers could re-shape our paradigms on gliomagenesis, particularly for recurrent tumors. Here we show that GBM EVs activate cancer-type signaling pathways in recipient astrocytes, promoting astrocyte migration towards the EVs, as well as astrocyte anchorage-independent growth in soft agar. Astrocytes release of various factors to generate a tumor-promoting milieu with increased tumor cell growth. We discuss the consequences of these phenomena in the context of our current therapies with a view towards therapeutic improvement.

Show speakers

12:15-12:30 Discussion

12:30-13:30

Lunch

Chair: Dr Andrew Devitt 13:30-17:00

8 talks Show detail Hide detail

Chairs

Dr Andrew Devitt, Aston University

13:30-14:00 Kesley Attridge

Abstract


14:00-14:15 Discussion

14:15-14:45 Biochemical characterisation and immune effects of different subtypes of extracellula vesicles released by dendritic cells

Dr Clothilde Thery

Abstract

Cells secrete into their environment different types of extracellular vesicles (EVs) that have distinct structural and biochemical properties depending on their intracellular site of origin. Exosomes are a subtype of EVs with a mean diameter lower than 150 nm that are formed inside multivesicular compartments of the endocytic pathway. Exosomes secreted by dendritic cells (DCs) have been shown to bear functional MHC class I and class II molecules able to activate cognate T cells. These findings motivated the use of DC-derived exosomes in cancer clinical trials, although with limited clinical effects. Other EVs also bear functional immune molecules and may thus represent alternative immunotherapy tools. However, side-by-side comparison of the immune effects of exosomes and other EVs has never been comprehensively performed. Here, we have isolated different subtypes of EVs simultaneously released by live human primary DCs and extensively characterize their proteome as well as their effects on primary lymphocytes. Subtypes of EVs included large ones (> 200nm diameter) budding from the plasma membrane of live cells, small ones (< 150 nm diameter), which include exosomes and other non-exosomal sEVs, and intermediate-size EVs, which we separated by a combination of differential ultracentrifugation, floatation into density gradients and immuno-isolation via different tetraspanins. Comparative proteomic analysis of these different EVs allowed us to propose a new cartography of EV-associated protein markers, including combinations that define endosome-derived exosomes. Functionnally, we show that all these EVs efficiently induced T lymphocyte proliferation, but that they differently skew the CD4 T helper immune response. Our results provide a refined framework for the use of EVs in immunotherapy.

Show speakers

14:45-15:00 Discussion

15:30-16:00 Is there more to the secretory phenotype in senescent cells?

Dr Ana O'Loghlen, Queen Mary, University of London

Abstract

Cellular senescence is an important tumour suppressive mechanism to prevent the propagation of damaged cells. It induces a permanent cell cycle arrest, where the cells are metabolically and transcriptionally active. Senescent cells undergo extensive changes in gene expression, including the expression of cell cycle inhibitors and a distinctive secretory phenotype called the SASP (senescence-associated secretory phenotype), which influences the tissue microenvironment. Senescent cells accumulate in preneoplastic lesions; however, the mechanisms regulating senescence and how senescent cells alter their surrounding microenvironment is not well known. In fact, conflicting data suggests that the SASP has both anti-oncogenic and pro-oncogenic properties depending on the tissue and on the context. Here, we will explore a potential role for extracellular vesicles (EV) secreted by senescent cells in contributing to this biphasic role for the SASP during senescence activation. Our data would help identify appropriate therapeutic targets and biomarkers to tackle senescent cells and cancer at the very early stages of the disease.

Show speakers

16:00-16:15 Discussion

16:15-16:45 Vesicular communication in cancer

Dr Matthias Belting, Skåne University Hospital

Abstract

Our studies elucidate the role of vesicular communication in tumor development, and how vesicular transport mechanisms can be exploited for specific targeting of treatment resistant cells of the hypoxic tumor microenvironment. Extracellular vesicles (EVs) represent relatively new signaling organelles in cell-cell communication that can carry complex biological information and elicit a pleiotropic response in recipient cells. We have found that EVs play an important role during hypoxia-mediated tumor development, and that EVs may provide a novel source of non-invasive biomarkers of the hypoxic tumor stress response. Further studies identified a key role of heparan sulfate proteoglycan-mediated endocytosis for the uptake and functional effect of EVs. More recently, we found that hypoxia down-regulates constitutive endocytosis through caveolin-1-mediated inhibition of dynamin-dependent, membrane raft endocytosis. However, several proteins can override caveolin-1 negative regulation, exhibiting increased internalization at hypoxia, further allowing antibody-mediated cytotoxin delivery and killing specifically of hypoxic cells. These data indicate that caveolin-1 modulates cell-surface proteome turnover at hypoxia with potential implications for specific targeting of the hypoxic tumor microenvironment. Based on these findings we will further explore the hypothesis that transport vesicles promote tumor aggressiveness and constitute novel therapeutic targets specifically related to typical features of the tumor microenvironment.

Show speakers

16:45-17:00 Discussion

24 January

Chair: Dr Stuart Hunt 09:00-12:30

9 talks Show detail Hide detail

Chairs

Dr Stuart Hunt, University of Sheffield

09:00-09:30 The role of EVs in NK cell-dependent immuunosurveillance of cancer

Professor Elke Pogge von Strandmann, University of Cologne

Abstract

Extracellular vesicles (EVs) are important mediators of intercellular communication and act on the adjacent stroma as well as in the periphery. Recently, EVs have been recognized to play a pathophysiological role in various diseases such as cancer.

Tumor cell-derived exosomes (Tex) have been shown to educate non-malignant cells to provide a tumor supporting microenvironment, which helps to circumvent immune detection and elimination. We identified a disease-related mRNA signature in vesicles from malignant B cells (Chronic Lymphocytic leukemia, CLL), which was even pronounced upon toll like receptor engagement used as a milieu-mimics. The transfer of such mRNAs to healthy bystander cells was detectable indicating that CLL-released vesicles spread tumor-milieu instructions within the CLL microenvironment. 

However, Tex with anti-tumor, immune-activating properties were described as well, which reflects the complexity of EVs. Activation of the innate immune receptor retinoic acid-inducible gene I (RIG-I) triggered the secretion of EVs from tumor cells, which exert anti-tumor activity in vitro and in vivo. RIG-I-induced EVs exhibited an increased expression of the NKp30-ligand (BAG6, BAT3) on their surface, triggering NK cell-mediated lysis of tumor cells via activation of the cytotoxicity NK cell-receptor NKp30. Moreover, systemic administration of RIG-I-induced tumor-EVs showed a potent anti-tumor activity in a melanoma mouse model in vivo. In conclusion our data establish a new RIG-I and EV-dependent pathway leading to NK cell-mediated tumor cell killing. The role of EVs as messengers affecting NK cell function in health and disease will be discussed. 

Show speakers

09:30-09:45 Discussion

09:45-10:15 Analysing the effects of extracellular vesicles on cancer invasion using human myoma tissue derived extracellular matrixes

Professor Tuula Salo, University of Oulu

Abstract

Translational cancer research has lacked human tissue in vitro models that mimic the natural tumor microenvironment matrix (TMEM). The 3D invasion pattern has been studied with organotypic models composed of rat tail type I collagen combined with mouse tumor derivatives, such as Matrigel®. However, these classical methods that mix matrixes from different species do not accurately mimic the composition of human TME. Our group has developed a 3D invasion assay using human uterine leiomyoma tissue discs. These hypoxic discs contain all essential TME components for in vitro invasion experiments. Both in native and lyophilized forms, these discs promote invasion and growth of the cancer cells - unlike e.g. healthy heart tissue. The invasion efficiency in the myoma discs can be analyzed by determining the degradation of collagen fibers together with histological and immunohistological staining of the tissue sections. Proteome analysis of myoma rinsing media revealed migration-enhancing factors whereas fragments derived from heart tissue rinsing media inhibited cancer migration. Myoma discs fit also for co-culture experiments of various TME cells, such as carcinoma associated fibroblasts, macrophages and inflammatory cells. We have also prepared myogel product from leiomyoma according to the method described for the preparation of Matrigel®. Myogel provides an excellent method for analyzing cancer cell migratory, invasive or adhesive properties, as well as potential chemotherapeutic compounds. Recently, myoma matrixes are used to test the effects of extracellular vesicles for cancer invasion. Thus, myoma discs together with myogel offer a practical human “TMEM mimicking kit” for translational cancer research purposes.

Show speakers

10:15-10:30 Discussion

11:00-11:15 Cancer exosomes establish a prometastatic inflammatory loop by engaging mesencgymal stem cells

Abstract

Contributory talk given by D. Michiel Pegtel

Metastasis formation and resistance to therapy, for example via STAT3 activation in tumor cells, could be a consequence of driver-mutations in cancerous ‘stem’ cells or of cancer-stroma interactions, but a role for mesenchymal stem stem cells (MSCs) is poorly understood. This talk will discuss how we explored in an in vivo osteosarcoma (OS) model how tumor exosomes may engage MSCs to facilitate tumor progression.

11:15-11:30 Extracellular vesicles and the pre-metastatic niche: a deadly conversation between prostate tumours and the bone

Abstract

Contributory talk given by Victoria James

The popular ‘seed and soil’ hypothesis proposes that organ preference patterns of metastasis result from favourable interactions between the metastatic cancer cells (‘seed’) and the organ microenvironment (‘soil’). However, what is less clear is whether primary tumours communicate with secondary sites in advance of tumour cell arrival, to create a ‘pre-metastatic niche’, to enhance tumour-cell colonisation at the most inefficient stage of metastasis. The role of extracellular-vesicles in this communication process remains to be explored.

In order to investigate how the cargo of prostate cancer (PCa) EVs could act to reprogramme the cells of the bone, to potentially create a supportive pre-metastatic niche. We have adapted a novel RNA tracking technique, to trace the route of the RNA cargo from PCa cells via EVs into recipient bone cells (osteoblasts), identifying several osteoblast specific RNAs suggesting PCa cells may selectively target cells of the bone with EV-mediated communication. 

Exposure of osteoblasts to PCa-EVs results in phenotypic changes indicative of microenvironment remodelling. Moreover, our data indicates treatment of the extracellular-environment can effectively block the uptake of PCa-EVs resulting in a reversal of the EV-activated osteoblast phenotype.

11:30-11:45 Discussion

11:45-12:15

Dr Stuart Hunt, University of Sheffield

Abstract


Show speakers

12:15-12:30 Discussion

12:30-13:30

Lunch

Chair: Dr Ryan Pink 13:30-17:00

7 talks Show detail Hide detail

Chairs

Dr Ryan Pink

13:30-14:00 Role of extracellular vesicle-mediated angiogenesis in hematologic neoplasias

Junko H. Ohyashiki, Tokyo Medical University

Abstract

It is widely accepted that tumor cells can affect surrounding cells by changing the tumor microenvironment (TME) from a normal to a tumor-supportive state that promotes tumor cell growth and survival, invasion, and chemoresistance. Like the TME in solid tumors, a tumor-supportive bone marrow microenvironment is required for disease progression in hematologic neoplasia. Bone marrow is a highly vascular tissue that is already hypoxic in nature. Increased bone marrow angiogenesis is related to disease severity and progression. Extracellular vesicles, especially exosomes, are currently recognized as mediators of intercellular communication. Hypoxia is a major regulator of exosomal content and affects angiogenesis in various types of hematologic neoplasia. For instance, exosomes secreted by multiple myeloma cells with chronic hypoxia enhance angiogenesis by targeting factor-inhibiting hypoxia-inducible factor-1 via miR-135b. We will discuss the exosome-mediated cell–cell interactions that modulate tumor angiogenesis, and a possible role of hypoxia in hemtologic neoplasias.

Show speakers

14:00-14:15 Discussion

14:15-14:45 Defining the role of tumour-secreted exosomes in metastasis

Dr Hector Peinado, Spanish National Cancer

Abstract

Cancer is a systemic disease, while most of the research effort has been focused on analyzing the primary tumor, there is a lack of information on how the tumor microenvironment influences metastasis. The importance of the microenvironment in metastasis is now fully acknowledged. Prominent roles for stromal cells, such as fibroblasts, endothelial cells, lymphatic endothelial cells, bone marrow-derived cells, soluble factors and secreted vesicles have been established. Our studies in metastatic melanoma demonstrated that tumor exosomes are a major tumor-derived factor that acts systemically to promote bone marrow-derived cells (BMDCs) recruitment to the tumor and metastatic microenvironments. We have demonstrated the role of tumor-secreted exosomes in premetastatic niche formation and metastatic organotropism. We are currently analyzing the dynamics of tumor-derived exosomes in the lymphatic system and their role establishing the pre-metastatic niche formation within the lymph node microenvironment. We found that tumor-secreted exosomes inducing a prolymph(angio)genic program and reprogramming of lymphatic endotelial cells within pre-metastatic lymph nodes. Our data support that tumor-secreted exosomes can be considered as a novel biomarker of lymph node metastasis. We found a signature associated to melanoma lymph node metastasis and we are currently analyzing circulating exosomes in the lymphatic fluid of cancer patients as a new approach to define new markers involved in tumor metastasis. Our data suggest that tumorsecreted exosomes act locally and systemically remodeling the lymphatic system favoring metastasis.

Show speakers

14:45-15:00 Discussion

15:30-16:00 Extracellular vesicles in the tumour microenvionment

Dr Muller Fabbri, University of Southern California

Abstract

MicroRNAs (miRNAs) are small non-coding RNAs (ncRNAs) that epigenetically regulate gene expression by affecting their translation at a post-transcriptional level. It has been shown that miRNAs can be functionally shuttled among neighboring cells, as cargo of extracellular vesicles.  The traditional mechanism of action of miRNAs implies that these small ncRNAs act by binding mostly (but not exclusively) to the 3’-untranslated region of target messenger RNAs, therefore impairing their translation into proteins. Such a dogma has been recently challenged by our discovery that miRNAs in extracellular vesicles can actually also work as “hormones” by binding to Toll-like receptor 8 (TLR8) in surrounding Tumor-Associated Macrophages (TAMs), within the Tumor Microenvironment. The binding of miRNAs to a receptor (that we called, miRceptor) leads to the activation of the NF-kB signaling and to an increased TAM secretion of cytokines with a pro-inflammatory and pro-tumoral role. Moreover, we showed that the miRNA-miRceptor interaction leads to the secretion of TAM-derived extracellular vesicles containing miRNAs that are shuttled back to cancer cells, where they target genes responsible for an increased resistance to chemotherapy. This aberrant cross-talk between cancer cells and TAMs, mediated by miRNAs in extracellular vesicles, can be exploited for the design and testing of new anti-cancer therapy, and to prevent/overcome the development of resistance to chemotherapy.

Show speakers

16:00-16:15 Discussion

16:15-17:00 Panel discussion: future directions

Extracellular vesicles and the tumour microenvironment The Royal Society, London 6-9 Carlton House Terrace London SW1Y 5AG UK