Comparative proteomics analysis of exosomes identifies key pathways and protein markers related to breast cancer metastasis

Proteomics analysis of circulating exosomes derived from cancer cells represents a promising approach to the elucidation of cell–cell communication and the discovery of putative biomarker candidates for cancer diagnosis and treatment. Nonetheless, the proteome of exosomes derived from cell lines with different metastatic capabilities still warrants further investigation. Researchers at SUNY Buffalo present a comprehensive quantitative proteomics investigation of exosomes isolated from immortalized mammary epithelial cells and matched tumor lines with different metastatic potentials in an attempt to discover exosome markers specific to breast cancer (BC) metastasis. A total of 2135 unique proteins were quantified with a high confidence level from 20 isolated exosome samples, including 94 of the TOP 100 exosome markers archived by ExoCarta. Moreover, 348 altered proteins were observed, among which several metastasis-specific markers, including cathepsin W (CATW), magnesium transporter MRS2 (MRS2), syntenin-2 (SDCB2), reticulon-4 (RTN), and UV excision repair protein RAD23 homolog (RAD23B), were also identified. Notably, the abundance of these metastasis-specific markers corresponds well with the overall survival of BC patients in clinical settings. Together, these data provide a valuable dataset for BC exosome proteomics investigation and prominently facilitate the elucidation of the molecular mechanisms underlying primary tumor development and progression.

Quantitative proteomics investigation of exosomes isolated from primary and derived EpH4-Ev cell lines with different tumorigenic and metastatic capabilities

(a) Specification of samples in this study; (b) the scheme for exosome sample preparation and proteomic experimental procedures; (c) images of exosomes isolated from the five cell lines; (d) Western blot assay of exosome markers FLOT1 and CD63 in whole-cell lysate and isolated exosome samples; (e) relative protein yield from exosome samples among the five cell lines.