Comparative proteomic analysis of three major extracellular classes
secreted from human adenocarcinoma and metastatic colorectal cancer
cells: exosomes, microparticles and shed midbody remnants
Abstract
Cell-derived extracellular vesicles (EVs) are evolutionary-conserved
secretory organelles that, based on their molecular composition, are
important intercellular signaling regulators. At least three classes of
circulating EVs are known based on mechanism of biogenesis: exosomes
(sEVs/Exos), microparticles (lEVs/MPs) and shed midbody remnants
(sMB-Rs). sEVs/Exos are of endosomal pathway origin, microparticles
(lEVs/MPs) from plasma membrane blebbing, and shed midbody remnants
(sMB-Rs) arise from symmetric cytokinetic abscission. Here, we isolate
sEVs/Exos, lEVs/MPs and sMB-Rs secreted from human isogenic primary
(SW480) and metastatic (SW620) colorectal cancer (CRC) cell lines in
milligram quantities for label-free MS/MS-based proteomic profiling.
Purified EVs revealed selective composition packaging of exosomal
protein markers in SW480/SW620-sEVs/Exos, metabolic enzymes in
SW480/SW620-lEVs/MPs, while centralspindlin complex proteins,
nucleoproteins, splicing factors, RNA granule proteins,
translation-initiation factors, and mitochondrial proteins selectively
traffic to SW480/SW620-sMB-Rs. Collectively, we identify 39 human
cancer-associated genes in EVs; 17 associated with SW480-EVs, 22 with
SW620-EVs. We highlight oncogenic receptors/transporters selectively
enriched in sEVs/Exos (EGFR/ FAS in SW480-Exos and MET, TGFBR2, ABCB1 in
SW620-sEVs/Exos). Interestingly, MDK, STAT1, and TGM2 are selectively
enriched in SW480-sMB-Rs, and ADAM15 to SW620-sMB-Rs. Our study reveals
sEVs/Exos, lEVs/MPs and sMB-Rs have distinct protein signatures that
open potential diagnostic avenues of distinct types of EVs for clinical
utility.