Summary The mutant form of the GTPase KRAS is a key driver of pancreatic cancer but remains a challenging therapeutic target. Exosomes, extracellular vesicles generated by all cells, are naturally present in the blood. Here we demonstrate that enhanced retention of exosomes in circulation, compared to liposomes, is due to CD47 mediated protection of exosomes from phagocytosis by monocytes and macrophages. Exosomes derived from normal fibroblast-like mesenchymal cells were engineered to carry siRNA or shRNA specific to oncogenic KRASG12D (iExosomes), a common mutation in pancreatic cancer. Compared to liposomes, iExosomes target oncogenic Kras with an enhanced efficacy that is dependent on CD47, and is facilitated by macropinocytosis. iExosomes treatment suppressed cancer in multiple mouse models of pancreatic cancer and significantly increased their overall survival. Our results inform on a novel approach for direct and specific targeting of oncogenic Kras in tumors using iExosomes.

Exosomes are a subclass of extracellular vesicles involved in intercellular communication that are released by all cell types, including cancer cells. Cancer exosomes carry malignant information in the form of proteins, lipids, and nucleic acids that can reprogram recipient cells. Exosomes have emerged as putative biological mediators in cancer contributing to major steps of disease progression. A leading role exists for cancer exosomes in specific aspects of tumor progression: modulation of immune response, tumor microenvironment reprogramming, and metastasis. This review will address the functions attributed to cancer exosomes in these three aspects of cancer biology, highlighting recent advances and potential limitations. Finally, we explore alternative strategies to develop better models to study cancer exosomes biology. .

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused the pandemic of the coronavirus induced disease 2019 (COVID-19) with evolving variants of concern. It remains urgent to identify novel approaches against broad strains of SARS-CoV-2, which infect host cells via the entry receptor angiotensin-converting enzyme 2 (ACE2). Herein, we report an increase in circulating extracellular vesicles (EVs) that express ACE2 (evACE2) in plasma of COVID-19 patients, which levels are associated with severe pathogenesis. Importantly, evACE2 isolated from human plasma or cells neutralizes SARS-CoV-2 infection by competing with cellular ACE2. Compared to vesicle-free recombinant human ACE2 (rhACE2), evACE2 shows a 135-fold higher potency in blocking the binding of the viral spike protein RBD, and a 60- to 80-fold higher efficacy in preventing infections by both pseudotyped and authentic SARS-CoV-2. Consistently, evACE2 protects the hACE2 transgenic mice from SARS-CoV-2-induced lung injury and mortality. Furthermore, evACE2 inhibits the infection of SARS-CoV-2 variants (α, β, and δ) with equal or higher potency than for the wildtype strain, supporting a broad-spectrum antiviral mechanism of evACE2 for therapeutic development to block the infection of existing and future coronaviruses that use the ACE2 receptor.

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ObjectiveIntratumor heterogeneity drives cancer progression and therapy resistance. However, it has yet to be determined whether and how subpopulations of cancer cells interact and how this interaction affects the tumour.DesignWe have studied the spontaneous flow of extracellular vesicles (EVs) between subpopulations of cancer cells: cancer stem cells (CSC) and non-stem cancer cells (NSCC). To determine the biological significance of the most frequent communication route, we used pancreatic ductal adenocarcinoma (PDAC) orthotopic models, patient-derived xenografts (PDXs) and genetically engineered mouse models (GEMMs).ResultsWe demonstrate that PDAC tumours establish an organised communication network between subpopulations of cancer cells using EVs called the EVNet). The EVNet is plastic and reshapes in response to its environment. Communication within the EVNet occurs preferentially from CSC to NSCC. Inhibition of this communication route by impairing Rab27a function in orthotopic xenographs, GEMMs and PDXs is sufficient to hamper tumour growth and phenocopies the inhibition of communication in the whole tumour. Mechanistically, we provide evidence that CSC EVs use agrin protein to promote Yes1 associated transcriptional regulator (YAP) activation via LDL receptor related protein 4 (LRP-4). Ex vivo treatment of PDXs with antiagrin significantly impairs proliferation and decreases the levels of activated YAP.Patients with high levels of agrin and low inactive YAP show worse disease-free survival. In addition, patients with a higher number of circulating agrin+ EVs show a significant increased risk of disease progression.ConclusionPDAC tumours establish a cooperation network mediated by EVs that is led by CSC and agrin, which allows tumours to adapt and thrive. Targeting agrin could make targeted therapy possible for patients with PDAC and has a significant impact on CSC that feeds the tumour and is at the centre of therapy resistance.

Rapid multiplex cell surface marker analysis can expedite investigations in which large number of antigens need to be analyzed. Simultaneous analysis of multiple surface antigens at the same level of sensitivity is however limited in the current golden standard analysis method, flow cytometry. In this paper we introduce a surface plasmon resonance imaging (SPRi)-based technique for 44-plex parameter analysis using a single sample, in less than 20 min. We analyzed the expression on cells from five different cancer cell lines by SPRi on a 44-plex antibody array including 4 negative controls and compared the output with flow cytometry. The combined correlation of the markers that showed expression by flow cytometry was 0.76. The results demonstrate as a proof of principle that SPRi can be applied for rapid semi-quantitative multiplex cell surface marker analysis.

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BackgroundThe inflammatory response to titanium implant-derived wear particles is considered as the hallmark of periprosthetic osteolysis, an event that cause pain, reduce patient motility, ultimately leading to the need of a revision surgery. Although macrophages are major cell players, other cell types such as bone cells can indirectly contribute to periprosthetic osteolysis, however the mechanisms are not fully understood. Exosomes (Exos) has been related with several bone pathologies, with growing body of literature recognizing them as actively shuttle molecules through the body, with their cargo being completely dependent of external stimuli (e.g. chemicals and metals ions and particles). Till the moment, the role of wear debris on osteoblasts exosomes biogenesis is absent and the possible contribution of Exos to osteoimmune communication and periprosthetic osteolysis is still in its infancy. Taking that in consideration, in this work we investigate the effect of wear debris on Exo biogenesis, where two bone cell models were exposed to titanium dioxide nanoparticles (TiO2 NPs) similar in size and composition to wear debris associated with prosthetic implants. The contribution of Exos to periprosthetic osteolysis was evaluated performing functional tests stimulating primary human macrophages with bone-derived Exos.ResultsFor the first time, we report that TiO2 NPs enter in multivesicular bodies, the nascent of Exos and altered osteoblasts derived exosomes secretion and cargo. No significant differences were observed in Exos morphology and size, however mass spectrometry analysis identified urokinase-type plasminogen activator (uPA), specifically enriched in Exos derived from bone cells pre-incubated with TiO2 NPs. Functional tests confirmed the activation of human macrophages towards a mixed phenotype with consequent secretion of pro and anti-inflammatory cytokines. ConclusionsThe external stimuli of osteoblasts to TiO2 NPs induced a dose dependent secretion of Exos, suggesting alterations in their biogenesis as well as in their cargo. Functional tests reveal that enriched uPA exosomal cargo is stimulating macrophages towards a mixed M1 and M2 phenotype inducing the release of pro-and anti-inflammatory signals that are characteristic of periprosthetic osteolysis. Interestingly, uPA may be proposed, in the future, as a possible candidate biomarker to early diagnose particle induced periprosthetic osteolysis, since uPA was also detected in the pseudocapsular interface around implants of patients with loosening of total hip prosthesis and joint replacement surgery, suggesting their active role in disease progression.