MicroRNA in exosomes isolated directly from the liver circulation in patients with metastatic uveal melanoma

Abstract

BackgroundUveal melanoma is a tumour arising from melanocytes of the eye, and 30 per cent of these patients develop liver metastases. Exosomes are small RNA containing nano-vesicles released by most cells, including malignant melanoma cells. This clinical translational study included patients undergoing isolated hepatic perfusion (IHP) for metastatic uveal melanoma, from whom exosomes were isolated directly from liver perfusates. The objective was to determine whether exosomes are present in the liver circulation, and to ascertain whether these may originate from melanoma cells.MethodsExosomes were isolated from the liver perfusate of twelve patients with liver metastases from uveal melanoma undergoing IHP. Exosomes were visualised by electron microscopy, and characterised by flow cytometry, Western blot and real-time PCR. Furthermore, the concentration of peripheral blood exosomes were measured and compared to healthy controls.ResultsThe liver perfusate contained Melan-A positive and RNA containing exosomes, with similar miRNA profiles among patients, but dissimilar miRNA compared to exosomes isolated from tumor cell cultures. Patients with metastatic uveal melanoma had a higher concentration of exosomes in their peripheral venous blood compared to healthy controls.ConclusionsMelanoma exosomes are released into the liver circulation in metastatic uveal melanoma, and is associated with higher concentrations of exosomes in the systemic circulation. The exosomes isolated directly from liver circulation contain miRNA clusters that are different from exosomes from other cellular sources.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2407-14-962) contains supplementary material, which is available to authorized users.

Extracellular Vesicles in Cancer: Cell-to-Cell Mediators of Metastasis

“…Serum-circulating exosomes from melanoma patients have been demonstrated to contain S100B and Melanoma Inhibitory Activity (MIA) (Alegre et al, 2016). High levels of exosomes carrying the melanoma marker Melan-A and characteristic miRNA signatures could be isolated from liver perfusates of patients with liver metastases from uveal melanoma (Eldh et al, 2014). Exosomal glypican-1 has also been proposed as a diagnostic and prognostic marker for pancreatic cancer disease (Melo et al, 2015).…”

Detailed analysis of the plasma extracellular vesicle proteome after separation from lipoproteins

“…Furthermore, patients suffering from diseases such as cancer have higher concentrations of circulating EVs, and these EVs can carry disease-specific molecules [3, 8–10]. Isolation of EVs from plasma and serum is, therefore, of great importance in the use of EVs as biomarkers for diseases such as cancer [3].…”

BRAFV600inhibition alters the microRNA cargo in the vesicular secretome of malignant melanoma cells

“…The levels of miR-211-5p in serum (∼200 μL) of mice bearing tumors and being treated with vemurafenib or dabrafenib, was not quantifiable with qPCR, and thus larger plasma or serum volumes may be required for its detection. Indeed, it is known from analysis of liver perfusates of liver metastatic uveal melanoma that melanoma-associated miRNAs can be detected in circulating exosomes when larger blood volumes are analyzed (19). Future clinical studies could determine whether miR-211-5p can be detected in clinical samples of melanoma patients undergoing BRAF-targeted therapy.…”