REG3β modifies cell tumor function by impairing extracellular vesicle uptake

Hypoxic papillary thyroid carcinoma cells-secreted exosomes deliver miR-221-3p to normoxic tumor cells to elicit a pro-tumoral effect by regulating the ZFAND5

Papillary thyroid cancer (PTC) has seen a worldwide expansion in incidence in the past three decades. Tumor-derived exosomes have been associated with the metastasis of cancer cells and are present within the local hypoxic tumor microenvironment, where they mediate intercellular communication by transferring molecules including microRNAs (miRNAs) between cells. Although miRNAs have been shown to serve as non-invasive biomarkers for cancer diagnosis, the role of hypoxia-induced tumor-derived exosomes in PTC progression remains unclear. Herein, we investigated the differentially expressed miRNA expression profiles from GEO datasets (GSE191117 and GSE151180) by using the DESeq package in R and identified a novel role for miR-221-3p as an oncogene in PTC development. In vivo and in vitro loss and gain assays were used to clarify the mechanism of hypoxic PTC cells derived exosomal-miR-221-3p in PTC. miR-221-3p was upregulated in human PTC plasma exosomes, tissues and cell lines. We found that hypoxic PTC cells derived exosomal-miR-221-3p promoted normoxic PTC cells proliferation, migration, invasion and epithelial-mesenchymal transition (EMT) in vitro, while inhibition of miR-221-3p limited PTC tumor growth in our PTC xenograft model in nude mice. We finally identified ZFAND5, to be a miR-221-3p target. Mechanistically, hypoxic PTC cell lines-derived exosomes carrying miR-221-3p promoted PTC tumorigenesis by regulating ZFAND5. Our findings further the understanding of the underlying mechanisms associated with PTC progression and identify exosomal-miR-221-3p as a potential biomarker for the diagnosis and prognosis of PTC patients. Our study also suggests that miR-221-3p inhibitors could be a potential treatment strategy for PTC.

From Exosome Biogenesis to Absorption: Key Takeaways for Cancer Research

Exosomes are mediators of intercellular communication in normal physiology and diseases. While many studies have emerged on the function of exosomal cargoes, questions remain regarding the origin of these exosomes. The packaging and secretion of exosomes in different contexts modify exosomal composition, which may in turn impact delivery, uptake and cargo function in recipient cells. A mechanistic understanding of exosome biology is therefore crucial to investigating exosomal function in complex biological systems and to the development of novel therapeutic approaches. Here, we outline the steps in exosome biogenesis, including endosome formation, MVB formation, cargo sorting and extracellular release, as well as exosome absorption, including targeting, interaction with recipient cells and the fate of internalized exosomes. In addition to providing a framework of exosome dynamics, we summarize current evidence on major pathways and regulatory mechanisms. We also highlight the various mechanisms observed in cancer and point out directions to improve study design in exosome biology. Further research is needed to illuminate the relationship between exosome biogenesis and function, which will aid the development of translational applications.

Extracellular Vesicles as "Very Important Particles" (VIPs) in Aging

In recent decades, extracellular vesicles have been recognized as "very important particles" (VIPs) associated with aging and age-related disease. During the 1980s, researchers discovered that these vesicle particles released by cells were not debris but signaling molecules carrying cargoes that play key roles in physiological processes and physiopathological modulation. Following the International Society for Extracellular Vesicles (ISEV) recommendation, different vesicle particles (e.g., exosomes, microvesicles, oncosomes) have been named globally extracellular vesicles. These vesicles are essential to maintain body homeostasis owing to their essential and evolutionarily conserved role in cellular communication and interaction with different tissues. Furthermore, recent studies have shown the role of extracellular vesicles in aging and age-associated diseases. This review summarizes the advances in the study of extracellular vesicles, mainly focusing on recently refined methods for their isolation and characterization. In addition, the role of extracellular vesicles in cell signaling and maintenance of homeostasis, as well as their usefulness as new biomarkers and therapeutic agents in aging and age-associated diseases, has also been highlighted.

Pancreatic cancer, stroma, and exosomes

In the pathogenesis of pancreatic adenocarcinoma, tumor stroma plays a key role in both aggressiveness, immune evasion, resistance to chemotherapy, and the ability to metastasize. Among the elements that characterize the behavior of the stroma, extracellular vesicles and, in particular, exosomes play an important role. These extracellular vesicles carry a wide range of bioactive molecules, from transcription factors to microRNAs, which can substantially alter the phenotype of the cellular components of the stroma. Exosomes are involved in the exchange of signals between tumor cells, tumor-associated macrophages, cancer-associated fibroblasts, and also with the healthy cells surrounding the tumor. They can transfer resistance to chemotherapeutic drugs, promote the epithelial-mesenchymal transition, modify the phenotype of macrophages, or induce the expression of molecules that alter the extracellular matrix to facilitate migration and metastasis. On the other hand, all these characteristics make these vesicles first-rate therapeutic targets, as controlling their functionality could greatly enhance the effectiveness of treatments that, today, are still far from be satisfactory.

Insight into Extracellular Vesicle-Cell Communication: From Cell Recognition to Intracellular Fate

Extracellular vesicles (EVs) are heterogamous lipid bilayer-enclosed membranous structures secreted by cells. They are comprised of apoptotic bodies, microvesicles, and exosomes, and carry a range of nucleic acids and proteins that are necessary for cell-to-cell communication via interaction on the cells surface. They initiate intracellular signaling pathways or the transference of cargo molecules, which elicit pleiotropic responses in recipient cells in physiological processes, as well as pathological processes, such as cancer. It is therefore important to understand the molecular means by which EVs are taken up into cells. Accordingly, this review summarizes the underlying mechanisms involved in EV targeting and uptake. The primary method of entry by EVs appears to be endocytosis, where clathrin-mediated, caveolae-dependent, macropinocytotic, phagocytotic, and lipid raft-mediated uptake have been variously described as being prevalent. EV uptake mechanisms may depend on proteins and lipids found on the surfaces of both vesicles and target cells. As EVs have been shown to contribute to cancer growth and progression, further exploration and targeting of the gateways utilized by EVs to internalize into tumor cells may assist in the prevention or deceleration of cancer pathogenesis.

Targeting REG3β limits pancreatic ductal adenocarcinoma progression through CTGF downregulation

The crosstalk between the transformed tumoral cells and their microenvironment is a key aspect for pancreatic ductal adenocarcinoma (PDAC) progression. This molecular dialog is intensively studied because it may result in an efficient therapeutic target. Contrary to this near microenvironment, the stromal portion in direct contact with the transformed cells, a far microenvironment, placed at the periphery of the tumor mass, produces factors signaling tumors. Among these factors, REG3β, produced by this part of the pancreas, is an important factor in promoting tumor progression. This paper demonstrated that targeting REG3β protein with specific antibodies limits the PDAC tumor growth in an orthotopic, syngeneic mice model induced by injection of Panc02 cells. Then, we showed that CTGF is over-expressed in response to REG3β in PDAC-derived cells. Moreover, inactivation of REG3β by treating tumors with anti-REG3β antibodies results in a strong decrease of CTGF in PDAC tumors. Lastly, we demonstrated that forced expression of CTGF in xenografted Panc02 cells abolishes the therapeutic effect of the anti-REG3β antibody treatment. Altogether, these results indicate that the effect of REG3β in promoting PDAC progression is mediated by CTGF over-activation. Thus, REG3β is a promising therapeutic target to treat PDAC with an original rationale. In conclusion, we demonstrated that the far microenvironment is essential for PDAC progression by producing active secretory factors, and some of them could be used as therapeutic targets.

A paradigm shift in cell-free approach: the emerging role of MSCs-derived exosomes in regenerative medicine

Recently, mesenchymal stem/stromal cells (MSCs) due to their pro-angiogenic, anti-apoptotic, and immunoregulatory competencies along with fewer ethical issues are presented as a rational strategy for regenerative medicine. Current reports have signified that the pleiotropic effects of MSCs are not related to their differentiation potentials, but rather are exerted through the release of soluble paracrine molecules. Being nano-sized, non-toxic, biocompatible, barely immunogenic, and owning targeting capability and organotropism, exosomes are considered nanocarriers for their possible use in diagnosis and therapy. Exosomes convey functional molecules such as long non-coding RNAs (lncRNAs) and micro-RNAs (miRNAs), proteins (e.g., chemokine and cytokine), and lipids from MSCs to the target cells. They participate in intercellular interaction procedures and enable the repair of damaged or diseased tissues and organs. Findings have evidenced that exosomes alone are liable for the beneficial influences of MSCs in a myriad of experimental models, suggesting that MSC- exosomes can be utilized to establish a novel cell-free therapeutic strategy for the treatment of varied human disorders, encompassing myocardial infarction (MI), CNS-related disorders, musculoskeletal disorders (e.g. arthritis), kidney diseases, liver diseases, lung diseases, as well as cutaneous wounds. Importantly, compared with MSCs, MSC- exosomes serve more steady entities and reduced safety risks concerning the injection of live cells, such as microvasculature occlusion risk. In the current review, we will discuss the therapeutic potential of MSC- exosomes as an innovative approach in the context of regenerative medicine and highlight the recent knowledge on MSC- exosomes in translational medicine, focusing on in vivo researches.

Exosomes as Pleiotropic Players in Pancreatic Cancer

Pancreatic cancer (PC) incidence is rising and due to late diagnosis, combined with unsatisfactory response to current therapeutic approaches, this tumor has an extremely high mortality rate. A better understanding of the mechanisms underlying pancreatic carcinogenesis is of paramount importance for rational diagnostic and therapeutic approaches. Multiple lines of evidence have showed that exosomes are actively involved in intercellular communication by transferring their cargos of bioactive molecules to recipient cells within the tumor microenvironment and systemically. Intriguingly, exosomes may exert both protumor and antitumor effects, supporting or hampering processes that play a role in the pathogenesis and progression of PC, including shifts in tumor metabolism, proliferation, invasion, metastasis, and chemoresistance. They also have a dual role in PC immunomodulation, exerting immunosuppressive or immune enhancement effects through several mechanisms. PC-derived exosomes also induce systemic metabolic alterations, leading to the onset of diabetes and weight loss. Moreover, exosomes have been described as promising diagnostic and prognostic biomarkers for PC. Their potential application in PC therapy as drug carriers and therapeutic targets is under investigation. In this review, we provide an overview of the multiple roles played by exosomes in PC biology through their specific cargo biomolecules and of their potential exploitation in early diagnosis and treatment of PC.

Reg3β: A Potential Therapeutic Target for Tissue Injury and Inflammation-Associated Disorders

Since regenerating islet-derived 3β (Reg3β) was first reported, various studies have been conducted to explore the involvement of Reg3β in a gamut of maladies, such as diabetes, pancreatitis, pancreatic ductal adenocarcinoma, and extrapancreatic maladies such as inflammatory bowel disease, acute liver failure, and myocardial infarction. Surprisingly, there is currently no systematic review of Reg3β. Therefore, we summarize the structural characteristics, transcriptional regulation, putative receptors, and signaling pathways of Reg3β. The exact functional roles in various diseases, especially gastrointestinal and liver diseases, are also discussed. Reg3β plays multiple roles in promoting proliferation, inducing differentiation, preventing apoptosis, and resisting bacteria. The present review may provide new directions for the diagnosis and treatment of gastrointestinal, liver, and pancreatic diseases.

Polyethylene Glycol 35 (PEG35) Modulates Exosomal Uptake and Function

Polyethylene glycols (PEGs) are neutral polymers widely used in biomedical applications due to its hydrophilicity and biocompatibility. Exosomes are small vesicles secreted by nearly all cell types and play an important role in normal and pathological conditions. The purpose of this study was to evaluate the role of a 35-kDa molecular weight PEG (PEG35) on the modulation of exosome-mediated inflammation. Human macrophage-like cells THP-1, epithelial BICR-18, and CAPAN-2 cells were exposed to PEG35 prior to incubation with exosomes of different cellular origins. Exosome internalization was evaluated by confocal microscopy and flow cytometry. In another set of experiments, macrophages were treated with increasing concentrations of PEG35 prior to exposure with the appropriate stimuli: lipopolysaccharide, BICR-18-derived exosomes, or exosomes from acute pancreatitis-induced rats. Nuclear Factor Kappa B (NFκB) and Signal transducer and activator of transcription 3 (STAT3) activation and the expression levels of pro-inflammatory Interleukin 1β (IL1β) were determined. PEG35 administration significantly enhanced the internalization of exosomes in both macrophages and epithelial cells. Further, PEG35 ameliorated the inflammatory response induced by acute pancreatitis-derived exosomes by reducing the expression of IL1β and p65 nuclear translocation. Our results revealed that PEG35 promotes the cellular uptake of exosomes and modulates the pro-inflammatory effect of acute pancreatitis-derived vesicles through inhibition of NFκB, thus emphasizing the potential value of PEG35 as an anti-inflammatory agent for biomedical purposes.

Potential diagnostic and therapeutic roles of exosomes in pancreatic cancer

Pancreatic cancer (PaCa) is considered an aggressive but still asymptomatic malignancy. Due to the lack of effective diagnostic markers, PaCa is often diagnosed during late metastatic stages. Besides surgical resection, no other treatment appears to be effective during earlier stages of the disease. Exosomes are related to a class of nanovesicles coated by a bilayer lipid membrane and enriched in protein, nucleic acid, and lipid contents. They are widely present in human body fluids, including blood, saliva, and pancreatic duct fluid, with functions in signal transduction and material transport. A large number of studies have suggested for a crucial role for exosomes in PaCa, which may be utilized to improve its future diagnosis and treatment, but the underlying molecular mechanisms as well as their potential clinical applications are largely unknown. By collecting and analyzing the most up-to-date literature, here we summarize the current progress of the clinical applications related to exosomes in PaCa. Therefore, we presently provide some rationale for the potential value of exosomes in PaCa, thereby promoting putative applications in targeted PaCa treatment.

Exosomes: A Potential Therapeutic Tool Targeting Communications between Tumor Cells and Macrophages

Exosomes comprise extracellular vesicles (EVs) with diameters between 30 and 150 nm. They transfer proteins, RNA, and other molecules from cell to cell, playing an important role in the interactions between cells. The tumor microenvironment (TME) has been found to contain various cells and molecules that have an important impact on tumor development. In the TME, macrophages have been found to have an important relationship with tumor cells, with tumors recruiting and inducing macrophages to become tumor-associated macrophages (TAMs), which promote tumor development. Recently, exosomes have been found to play a critical role in the interaction between tumor cells and macrophages. Thus, in this review, we summarize the roles and mechanisms of exosomes in the interaction between tumor cells and macrophages and the potential methods by which exosomes are used to target the communication between tumor cells and macrophages to treat cancer.

Functional proteins of mesenchymal stem cell-derived extracellular vesicles

Extracellular vesicles (EVs) contain proteins, microRNAs, mRNAs, long non-coding RNAs, and phospholipids, and are a novel mechanism of intercellular communication. It has been proposed that the immunomodulatory and regenerative effects of mesenchymal stem/stromal cells (MSCs) are mainly mediated by soluble paracrine factors and MSC-derived EVs (MSC-EVs). Recent studies suggest that MSC-EVs may serve as a novel and cell-free alternative to whole-cell therapies. The focus of this review is to discuss the functional proteins which facilitate the effects of MSC-EVs. The first section of the review discusses the general functions of EV proteins. Next, we describe the proteomics of MSC-EVs as compared with their parental cells. Then, the review presents the current knowledge that protein contents of MSC-EVs play an essential role in immunomodulation and treatment of various diseases. In summary, functional protein components are at least partially responsible for disease-modulating capacity of MSC-EVs.

Involvement of extracellular vesicles in the macrophage-tumor cell communication in head and neck squamous cell carcinoma

Background

Exosomes are cell-derived vesicles that mediate cellular communication in health and multiple diseases, including cancer. However, its role in head and neck cancer has been poorly defined. Here, we investigated the relevance of exosomes in the signaling between larynx cancer cells and macrophages.

Methods

Exosomes from THP1 macrophages and BICR18 cells (a larynx squamous cell carcinoma cell line) were purified and their role in the cancer cell migration, macrophage phenotype and immunosuppressive activity was evaluated. The activation of STAT3 signal transduction in macrophages in response to exosomes obtained from cancer cells was also evaluated.

Results

Macrophages foster the cancer cell migration and this effect is mediated by exosome signaling. On the other hand, exosomes also induce the expression of IL-10 in macrophages and PD-L1 in cancer cells, thus resulting in the promotion of an immunosuppressive environment. Moreover, we observed that the effects induced in cancer cells are mediated by the exosome-depending activation of STAT-3 signal transduction pathway.

Conclusions

Our study indicates that exosomes released by both macrophages and cancer cells plays a critical role in tumor progression in larynx cancer and might be a potential target for therapeutic intervention in head and neck cancer.

Four Decades After the Discovery of Regenerating Islet-Derived (Reg) Proteins: Current Understanding and Challenges

Regenerating islet-derived (Reg) proteins have emerged as multifunctional agents with pro-proliferative, anti-apoptotic, differentiation-inducing and bactericidal properties. Over the last 40 years since first discovered, Reg proteins have been implicated in a gamut of maladies including diabetes, various types of cancer of the digestive tract, and Alzheimer disease. Surprisingly though, a consensus is still absent on the regulation of their expression, and molecular underpinning of their function. Here, we provide a critical appraisal of recent findings in the field of Reg protein biology. Specifically, the structural characteristics are reviewed particularly in connection with established or purported functions of different members of the Reg family. Moreover, Reg expression patterns in different tissues both under normal and pathophysiological conditions are summarized. Putative receptors and cascades reported to relay Reg signaling inciting cellular responses are presented aiming at a better appreciation of the biological activities of the distinct Reg moieties. Challenges are also discussed that have hampered thus far the rapid progress in this field such as the use of non-standard nomenclature for Reg molecules among various research groups, the existence of multiple Reg members with significant degree of homology and possibly compensatory modes of action, and the need for common assays with robust readouts of Reg activity. Coordinated research is warranted going forward, given that several research groups have independently linked Reg proteins to diseased states and raised the possibility that these biomolecules can serve as therapeutic targets and biomarkers.

The Role of Exosomes in Pancreatic Cancer

Pancreatic cancer remains one of the deadliest cancers in the world, as a consequence of late diagnosis, early metastasis and limited response to chemotherapy, under which conditions the potential mechanism of pancreatic cancer progression requires further study. Exosomes are membrane vesicles which are important in the progression, metastasis and chemoresistance in pancreatic cancer. Additionally, they have been verified to be potential as biomarkers, targets and drug carriers for pancreatic cancer treatment. Thus, studying the role of exosomes in pancreatic cancer is significant. This paper focuses on the role of exosomes in the proliferation, metastasis and chemoresistance, as well as their potential applications for pancreatic cancer.

Analysis of extracellular vesicles generated from monocytes under conditions of lytic cell death

Extracellular vesicles (EVs) are an important class of membrane-bound structures that have been widely investigated for their roles in intercellular communication in the contexts of tumor progression, vascular function, immunity and regenerative medicine. Much of the current knowledge on the functions of EVs pertains to those derived from viable cells (e.g. exosomes and microvesicles) or apoptotic cells (e.g. apoptotic bodies) whilst the generation of EVs from dying cells under non-apoptotic conditions remains poorly characterized. Herein, the release of EVs from THP-1 monocytes under conditions of primary necrosis, secondary necrosis and pyroptosis, was investigated. A comprehensive analysis of THP-1-derived EVs revealed that cells undergoing lytic forms of cell death generated a high number of EVs compared with viable or apoptotic cells in vitro. Differential centrifugation via 16,000 g and 100,000 g revealed that dying THP-1 cells release both medium and small EVs, respectively, consistent with the known characteristics of microvesicles and/or exosomes. In addition, large EVs isolated via 2000 g centrifugation were also present in all samples. These findings suggest that lytic cell death under both sterile and non-sterile inflammatory conditions induces monocytes to generate EVs, which could potentially act as mediators of cell-to-cell communication.

Extracellular vesicle‑delivered miR‑505‑5p, as a diagnostic biomarker of early lung adenocarcinoma, inhibits cell apoptosis by targeting TP53AIP1

Lung adenocarcinoma (LA) is the most commonly occurring histological type of non‑small cell lung cancer. Diagnosis and treatment of LA remain a major clinical challenge. In the present study, to identify early LA biomarkers, extracellular vesicles (EVs) were separated from the plasma samples from 153 patients with LA and 75 healthy controls. microRNA (miRNA) expression profiling was performed at the screening stage (5 patients with LA vs. 5 controls), followed by verification at the validation stage (40 patients with LA vs. 20 controls) using reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR). The four disordered miRNAs (miR‑505‑5p, miR‑486‑3p, miR‑486‑3p and miR‑382‑3p) identified in the plasma EVs were further evaluated at the testing stage (108 patients with LA vs. 50 controls) by RT‑qPCR. It was revealed that miR‑505‑5p was upregulated, whereas miR‑382‑3p was downregulated, in the EVs from patients with LA. Furthermore, miR‑505‑5p was also upregulated in tumor tissues, compared with adjacent non‑tumor control tissues. Subsequently, the direct targets of miR‑505‑5p were predicted using bioinformatics analyses, and verified by luciferase assay and immunoblotting. The present study determined that miR‑505‑5p functions as an oncogene, promoting lung cancer cell proliferation and inhibiting cancer cell apoptosis via the targeting of tumor protein P53‑regulated apoptosis‑inducing protein 1 (TP53AIP1). Finally, it was confirmed that miR‑505‑5p in plasma EVs could be delivered to lung cancer cells, inhibiting cell apoptosis and promoting cell proliferation by targeting TP53AIP1. In conclusion, the present study indicated that miRNA‑505‑5p functions as an oncogene that may be used as a novel biomarker for the diagnosis and treatment of LA.

The Role of Extracellular Vesicles in Cancer: Cargo, Function, and Therapeutic Implications

Extracellular vesicles (EVs) are a heterogeneous collection of membrane-bound structures that play key roles in intercellular communication. EVs are potent regulators of tumorigenesis and function largely via the shuttling of cargo molecules (RNA, DNA, protein, etc.) among cancer cells and the cells of the tumor stroma. EV-based crosstalk can promote proliferation, shape the tumor microenvironment, enhance metastasis, and allow tumor cells to evade immune destruction. In many cases these functions have been linked to the presence of specific cargo molecules. Herein we will review various types of EV cargo molecule and their functional impacts in the context of oncology.

Extracellular Vesicles: A New Perspective in Tumor Therapy

In recent years, the study of extracellular vesicles has been booming across various industries. Extracellular vesicles are considered one of the most important physiological endogenous carriers for the specific delivery of molecular information (nucleonic acid, cytokines, enzymes, etc.) between cells. It has been discovered that they perform a critical role in promoting tumor cell growth, proliferation, tumor cell invasion, and metastatic ability and regulating the tumor microenvironment to promote tumor cell communication and metastasis. In this review, we will discuss (1) the mechanism of extracellular vesicles generation, (2) their role in tumorigenesis and cancer progression (cell growth and proliferation, tumor microenvironment, epithelial-mesenchymal transition (EMT), invasion, and metastasis), (3) the role of extracellular vesicles in immune therapy, (4) extracellular vesicles targeting in tumor therapy, and (5) the role of extracellular vesicles as biomarkers. It is our hope that better knowledge and understanding of the extracellular vesicles will offer a wider range of effective therapeutic targets for experimental tumor research.

Extracellular vesicles as mediators of the progression and chemoresistance of pancreatic cancer and their potential clinical applications

Pancreatic cancer is one of the most lethal cancers worldwide due to its insidious symptoms, early metastasis, and chemoresistance. Hence, the underlying mechanisms contributing to pancreatic cancer progression require further exploration. Based on accumulating evidence, extracellular vesicles, including exosomes and microvesicles, play a crucial role in pancreatic cancer progression and chemoresistance. Furthermore, they also possess the potential to be promising biomarkers, therapy targets and tools for treating pancreatic cancer. Therefore, in-depth studies on the role of extracellular vesicles in pancreatic cancer are meaningful. In this review, we focus on the regulatory effects of extracellular vesicles on pancreatic cancer progression, metastasis, cancer-related immunity and chemoresistance, particularly their potential roles as biomarkers and therapeutic targets.

Factors released by the tumor far microenvironment are decisive for pancreatic adenocarcinoma development and progression

The REG3β protein was identified more than 2 decades ago, but its role in PDAC development was only recently reported. In Pancreatic Ductal Adenocarcinoma (PDAC), REG3β protein is expressed and released by the far microenvironment, which is situated out of the tumor, at the periphery of the tumor mass, and is part of the healthy peri-tumoral region. This compartment is completely unrelated to the classical microenvironment that corresponds to the intra-tumoral stoma. Clinically relevant, the far microenvironment, and the factors released by it, could be novel and original therapeutic targets for treating patients with a PDAC. In this way we recently demonstrated that REG3β is an essential soluble factor necessary for PDAC development which is able to stimulate several simultaneous pro-tumoral mechanisms. We also find that secreted REG3β boosts interactions between epithelial cells and immune cells by activating the CXCL12/CXCR4 signaling cascade, which facilitates tumor escape through evasion of immune surveillance, and promotes metastasis. In addition, REG3β interfere the intercellular communication inside the tumor mediated by extracellular vesicles, resulting in relevant changes in macrophage phenotype or tumor cell migration. Therefore, we are proposing to call as near microenvironment to the classical microenvironment that is constituted by fibroblasts, inflammatory cells and fibers and located into the tumor, and as far microenvironment, which is constituted by the parenchymal non transformed cells located at the periphery of the tumor mass.