Reprint of "EXOSOME LEVELS IN HUMAN BODY FLUIDS: A TUMOR MARKER BY THEMSELVES?"

Isolation of exosomes from whole blood by a new microfluidic device: proof of concept application in the diagnosis and monitoring of pancreatic cancer

BACKGROUND

Exosomes are endocytic-extracellular vesicles with a diameter around 100 nm that play an essential role on the communication between cells. In fact, they have been proposed as candidates for the diagnosis and the monitoring of different pathologies (such as Parkinson, Alzheimer, diabetes, cardiac damage, infection diseases or cancer).

RESULTS

In this study, magnetic nanoparticles (Fe3O4NPs) were successfully functionalized with an exosome-binding antibody (anti-CD9) to mediate the magnetic capture in a microdevice. This was carried out under flow in a 1.6 mm (outer diameter) microchannel whose wall was in contact with a set of NdFeB permanent magnets, giving a high magnetic field across the channel diameter that allowed exosome separation with a high yield. To show the usefulness of the method, the direct capture of exosomes from whole blood of patients with pancreatic cancer (PC) was performed, as a proof of concept. The captured exosomes were then subjected to analysis of CA19-9, a protein often used to monitor PC patients.

CONCLUSIONS

Here, we describe a new microfluidic device and the procedure for the isolation of exosomes from whole blood, without any need of previous isolation steps, thereby facilitating translation to the clinic. The results show that, for the cases analyzed, the evaluation of CA19-9 in exosomes was highly sensitive, compared to serum samples.

Circulating Cancer Stem Cell-Derived Extracellular Vesicles as a Novel Biomarker for Clinical Outcome Evaluation

The recent introduction of the "precision medicine" concept in oncology pushed cancer research to focus on dynamic measurable biomarkers able to predict responses to novel anticancer therapies in order to improve clinical outcomes. Recently, the involvement of extracellular vesicles (EVs) in cancer pathophysiology has been described, and given their release from all cell types under specific stimuli, EVs have also been proposed as potential biomarkers in cancer. Among the techniques used to study EVs, flow cytometry has a high clinical potential. Here, we have applied a recently developed and simplified flow cytometry method for circulating EV enumeration, subtyping, and isolation from a large cohort of metastatic and locally advanced nonhaematological cancer patients (N = 106); samples from gender- and age-matched healthy volunteers were also analysed. A large spectrum of cancer-related markers was used to analyse differences in terms of peripheral blood circulating EV phenotypes between patients and healthy volunteers, as well as their correlation to clinical outcomes. Finally, EVs from patients and controls were isolated by fluorescence-activated cell sorting, and their protein cargoes were analysed by proteomics. Results demonstrated that EV counts were significantly higher in cancer patients than in healthy volunteers, as previously reported. More interestingly, results also demonstrated that cancer patients presented higher concentrations of circulating CD31+ endothelial-derived and tumour cancer stem cell-derived CD133 + CD326- EVs, when compared to healthy volunteers. Furthermore, higher levels of CD133 + CD326- EVs showed a significant correlation with a poor overall survival. Additionally, proteomics analysis of EV cargoes demonstrated disparities in terms of protein content and function between circulating EVs in cancer patients and healthy controls. Overall, our data strongly suggest that blood circulating cancer stem cell-derived EVs may have a role as a diagnostic and prognostic biomarker in cancer.

Prostate cancer cells and exosomes in acidic condition show increased carbonic anhydrase IX expression and activity

Acidity and hypoxia are crucial phenotypes of tumour microenvironment both contributing to the selection of malignant cells under a micro evolutionistic pressure. During the tumour progression, nanovesicles, called exosomes and the metalloenzyme carbonic anhydrase IX (CA IX) affect the tumour growth and proliferation. Exosomes are released into the tumour microenvironment and spilt all over the body, while CA IX is a tumour-associated protein overexpressed in many different solid tumours. In the present study, to better understand the relationships between exosomes and CA IX, it has been used an in vitro cellular model of cells cultured in different pH conditions. The results showed that the acidic microenvironment induced upregulation of both expression and activity of CA IX in cancer cells and their exosomes, together with increasing the number of released exosomes. These data strongly support the importance of CA IX as a cancer biomarker and as a valuable target of new anticancer therapies.

A Role of Tumor-Released Exosomes in Paracrine Dissemination and Metastasis

Metastatic diffusion is thought to be a multi-step phenomenon involving the release of cells from the primary tumor and their diffusion through the body. Currently, several hypotheses have been put forward in order to explain the origin of cancer metastasis, including epithelial⁻mesenchymal transition, mutagenesis of stem cells, and a facilitating role of macrophages, involving, for example, transformation or fusion hybridization with neoplastic cells. In this paradigm, tumor-secreted extracellular vesicles (EVs), such as exosomes, play a pivotal role in cell communications, delivering a plethora of biomolecules including proteins, lipids, and nucleic acids. For their natural role in shuttling molecules, EVs have been newly considered a part of the metastatic cascade. They have a prominent role in preparing the so-called "tumor niches" in target organs. However, recent evidence has pointed out an even more interesting role of tumor EVs, consisting in their ability to induce malignant transformation in resident mesenchymal stem cells. All in all, in this review, we discuss the multiple involvements of EVs in the metastatic cascade, and how we can exploit and manipulate EVs in order to reduce the metastatic spread of malignant tumors.

Moving the systemic evolutionary approach to cancer forward: Therapeutic implications

We have previously presented a new Systemic Evolutionary Theory of Cancer (SETOC) based on the failure of proper endosymbiosis in eukaryotic cells. Here, we propose that the progressive uncoupling of two endosymbiotic subsystems (information and energy) inside the cell, as a consequence of long-term injuries, gives rise to alterations (i) in tissue interactions and (ii) in cell organization. In the first case, we argue that the impairment of both the coherent state and the synergy between intercellular communications underpins the onset of tissue dysplasia, that usually evolves towards cancer development. In the second case, we suggest that the rupture of endosymbiosis drives a sort of cell regression towards a protist-like entity represented by the concept of "de-emergence" postulated in our systemic evolutionary approach to carcinogenesis. This conceptual association of the cancer cell with a protist-like organism could support the development of novel cancer therapeutic approaches. To this end, we propose a paradigm shift in cancer pharmacology since: i) our knowledge of cancer pathophysiology as a complex system is insufficient, despite a vast knowledge of molecular mechanisms underlying cancer; ii) current cancer pharmacology deals only with microvariables (e.g. gene or protein targets), which do not account for the integrated pathophysiology of cancer, rather than with macrovariables (e.g. pH, membrane potential, electromagnetic fields, cell communications and so on) and mesovariables (between micro and macro), such as the interaction between various cellular components including cellular organelles. This paradigm shift should allow cancer pharmacology to move forward from molecular treatments (focusing on single targets) to modular treatments that consider cancer-related processes (i.e. inflammation, coagulation, etc.) or even to a sort of ecosystemic treatment addressing the whole functioning of the "cancer ecosystem". Examples of ecosystems treatment may be natural plant derivatives that act synergistically or pulsed electromagnetic fields which can act on particular biological processes in cancer cells. In addition, we need different working theoretical models on which to base new anticancer pharmacological approaches. Finally, we examine what value our systemic evolutionary approach could add to cancer treatments, in particular in liver cancer as a paradigm for developing potential applications.