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Dryad

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

Abstract

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.