Abstract
Purpose:
Exosomes are particles derived from cell membranes with sizes ranging between 20-120 nm. They are also attributed a role of intercellular messengers since the interior contains a variety of proteins and microRNAs. This fact makes them object of study as oncogenic biomarkers with prognostic value. The objective was to determine whether uveal melanoma cells (UM) release exosomes and to analyze their proteome.
Methods:
The secretome from a primary human UM cell culture established previously by our group (UM-A), and from a spontaneous cell line arisen from this culture, characterized by more invasive capability, were collected. Exosomes were isolated (ExoQuick-TC) and analyzed by 2-dimensional Differential In Gel Electrophoresis (DIGE) to quantitatively compare the differences in the protein content of exosomes from both cultures. Significant protein differences among exosomes (SameSpots, TOTALLAB) were identified by mass spectrometry analysis (MALDI-TOF/TOF).
Results:
118 significant differences (p<0.001) between the two samples of exosomes were detected. From 67 proteins identified, proteins such as the mitogen activated protein kinase 3 (ERK1), and transcription regulators such as zinc finger protein 224 or LAMTOR3, were elevated in exosomes secreted by the more invasive cell line; angiogenesis inhibitors such as PEGF were found in the less invasive primary culture.
Conclusions:
We show for the first time the identification and characterization of exosomes released by UM cells with different invasion potential. Our results indicate that the proteomic exosome profiles vary depending on the aggressiveness of the cell line. Certain proteins from UM exosomes could be considered as potential biomarkers or treatment targets in the future.