iTRAQ proteomics dataset on ceramide-dependent exosomal cargoes from SW480 and SW620 cells

Cancer metastasis is largely influenced by cell–cell communication, to
which exosomes play a vital role. Exosomes are small extracellular
vesicles (sEVs) that originate as intraluminal vesicles (ILVs) within
multivesicular bodies (MVBs) during endosome maturation. ILV formation
depends on several pathways, including that of ceramide synthesis by
neutral sphingomyelinase 2 [nSMase2]. Colorectal cancer (CRC)-derived sEVs
are reported to carry a diverse range of metastatic cargo proteins;
however, segregation of them in the ceramide-dependent sEV pool (sEVCer)
remains unexplored. The current study aimed to identify the metastatic
proteins that are secreted through sEVCer, from CRC cells of variable
metastatic potentials. Primary (SW480) and metastatic (SW620) CRC cells
were treated with nSMase2 blocker and sEVs were isolated, followed by
extraction of the sEV proteins for a quantitative proteomic profiling
using isobaric tags for relative and absolute quantitation (iTRAQ). In
total, 1781 proteins were identified with unused protein score
>1.3. Of these identified proteins, 22.8% and 17.01% were found to
be depleted within sEVs of the treated SW480 and SW620 cells,
respectively. These depleted protein pools represented the cargo that are
preferentially secreted through sEVCer in respective cell types
(CargoCer-SW480 and CargoCer-SW620). CargoCer-SW480 overrepresented
integrin signalling pathway members and CargoCer-SW620 overrepresented
integrin as well as platelet-derived growth factor (PDGF) signalling
pathway members. Interestingly, the uniquely overrepresented
CargoCer-SW480 and CargoCer-SW620 were biologically connected, rendering
possible transfer of metastatic cues via sEVCer. Overall, this study
identified CargoCer and their dynamics over progressive CRC stages, and
thereby opens up a new research direction for exploring the flow of
metastatic cues through uptake and release of sEVCer.