Uveal Melanoma-Derived Extracellular Vesicles Display Transforming Potential and Carry Protein Cargo Involved in Metastatic Niche Preparation

Abstract

Extracellular vesicles (EVs) carry molecules derived from donor cells and are able to alter the properties of recipient cells. They are important players during the genesis and progression of tumors. Uveal melanoma (UM) is the most common primary intraocular tumor in adults and is associated with a high rate of metastasis, primarily to the liver. However, the mechanisms underlying this process are poorly understood. In the present study, we analyzed the oncogenic potential of UM-derived EVs and their protein signature. We isolated and characterized EVs from five UM cell lines and from normal choroidal melanocytes (NCMs). BRCA1-deficient fibroblasts (Fibro-BKO) were exposed to the EVs and analyzed for their growth in vitro and their reprograming potential in vivo following inoculation into NOD-SCID mice. Mass spectrometry of proteins from UM-EVs and NCM-EVs was performed to determine a protein signature that could elucidate potential key players in UM progression. In-depth analyses showed the presence of exosomal markers, and proteins involved in cell-cell and focal adhesion, endocytosis, and PI3K-Akt signaling pathway. Notably, we observed high expression levels of HSP90, HSP70 and integrin V in UM-EVs. Our data bring new evidence on the involvement of UM-EVs in cancer progression and metastasis.

The Analysis of Inflammation-Related Proteins in a Cargo of Exosomes Derived from the Serum of Uveal Melanoma Patients Reveals Potential Biomarkers of Disease Progression

“…They found out that their content is associated with cell-cell and focal adhesion, endocytosis, and PIK3-Akt signalling pathway. Moreover, the exosome-treated BRCA1-deficient fibroblast was shown to acquire a more CAF-like phenotype, with increased proliferation, migration, and invasion ability and this was related to enhanced tumour cells growth in vivo [24].…”

“…That is why in the presented study, we decided to estimate the cargo of the UM exosomes derived from the serum of patients with primary and metastatic disease to find specific proteins responsible for the spread of UM cells, which possibly could be used as a predictive biomarker. The existence of UM-specific exosomes has already been confirmed in several studies focusing on their protein content in vitro (in cell culture supernatant) and in vivo (in the vitreous humour, blood serum, and hepatic circulation system) [24,25,[28][29][30]. However, their role as potential carriers of biomarkers for early detection of UM progression has not been studied.…”

“…The existence of UM-derived exosomes has been confirmed by observing their presence in the hepatic circulation system, vitreous humour, blood serum, and in vitro cell culture. The protein cargo was analyzed in exosomes, ectosomes derived from UM, and normal melanocyte cell lines [24,25]. These results showed that the protein cargo of UM-derived extracellular vesicles may have transforming potential and could contribute to the preparation of the metastatic niche.…”

Anticancer Effects of Mifepristone on Human Uveal Melanoma Cells

“…Cell lines were authenticated by Short Tandem Repeat (University of Arizona Genetic Core). Normal Choroidal Melanocytes (NCM) were isolated from donor eyes following a previously established protocol [34]. Human eyes were used in accordance with the McGill University Health Centre (MUHC) Research Ethics Board (2019-5314).…”

Proteomics of Primary Uveal Melanoma: Insights into Metastasis and Protein Biomarkers

“…Previous proteomic studies of pUM tissues from our laboratory [ 33 ] and others [ 34 , 35 , 36 ] have been limited by small sample sizes. Previous in vitro UM proteomic studies have characterized the secretome and proteome of primary UM cell lines, cultured choroid melanocytes, cultured liver metastases [ 37 , 38 , 39 , 40 , 41 , 42 , 43 ], and have identified cargo in extracellular vesicles from cultured pUM [ 44 ]. This study identifies a significant number of differentially expressed pUM proteins that provide bioinformatic insights into the differences between metastasizing and non-metastasizing pUM, and a foundation for protein-based assays for UM metastasis.…”