Abstract
Purpose :
Uveal melanoma (UM) is the most common intraocular malignancy in adults. It is associated with high mortality rate due to metastasis. In many diseases, extracellular vesicles (EVs) orchestrate several processes by altering the properties of recipient cells. We reported that UM-derived EVs display transforming potential and carry proteins involved in metastatic niche preparation. Herein, we sought to determine whether UM EVs proteomic load will inform on novel therapeutic targets for this deadly malignancy
Methods :
EVs were isolated from 5 UM cell lines and normal choroidal melanocytes (NCMs), and from different analytes (aqueous humor (AH), vitreous humor (VH) and plasma) collected from UM patients and cancer-free control individuals. Isolated EVs were characterized physically using nanoparticle tracking and electron microscopy analyses, and phenotypically by immunoblotting using specific EV markers. Mass spectrometry of isolated EV proteins was performed to determine soluble protein differentially expressed in UM samples compared to matched controls. Dataset outputs were loaded onto Scaffold.v4.10.0 for quantification and statistical treatment. The identified proteins were analyzed using the DAVID Bioinformatics database, and the FunRich software
Results :
Isolated EVs displayed characteristics of exosomes regarding their size and marker expression. In addition, proteomic analyses showed the presence of exosomal markers. Proteome outputs from both UM cell lines, and UM analytes datasets were screened for soluble factors. Of these, we selected proteins that were present in both datasets and that were overexpressed in UM cell line-derived EVs compared to those found in NCM-EVs. We than focused on proteins present in EVs isolated from the AH and VH. We determined 16 proteins involved in cell proliferation, survival and invasion, and metastatic niche organization
Conclusions :
Our analyses indicate that protein cargo of EVs isolated from UM cell lines and UM patient analytes displayed consistent profiles. Aside from determining signatures to elucidate key players in UM progression and metastasis (i.e., liquid biopsy for patient monitoring), we report herein that EV protein cargo is a source for the discovery of new UM therapeutic targets. Our established short-list of proteins is being tested on UM cells to determine the effects of targeting these protein candidates on UM progression
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.