Plasma exosomes stimulate breast cancer metastasis through surface interactions and activation of FAK signaling.

PURPOSE: The interaction between malignant cells and surrounding healthy tissues is a critical factor in the metastatic progression of breast cancer (BC). Extracellular vesicles, especially exosomes, are known to be involved in inter-cellular communication during cancer progression. In the study presented herein, we aimed to evaluate the role of circulating plasma exosomes in the metastatic dissemination of BC and to investigate the underlying molecular mechanisms of this phenomenon. METHODS: Exosomes isolated from plasma of healthy female donors were applied in various concentrations into the medium of MDA-MB-231 and MCF-7 cell lines. Motility and invasive properties of BC cells were examined by random migration and Transwell invasion assays, and the effect of plasma exosomes on the metastatic dissemination of BC cells was demonstrated in an in vivo zebrafish model. To reveal the molecular mechanism of interaction between plasma exosomes and BC cells, a comparison between un-treated and enzymatically modified exosomes was performed, followed by mass spectrometry, gene ontology, and pathway analysis. RESULTS: Plasma exosomes stimulated the adhesive properties, two-dimensional random migration, and transwell invasion of BC cells in vitro as well as their in vivo metastatic dissemination in a dose-dependent manner. This stimulatory effect was mediated by interactions of surface exosome proteins with BC cells and consequent activation of focal adhesion kinase (FAK) signaling in the tumor cells. CONCLUSIONS: Plasma exosomes have a potency to stimulate the metastasis-promoting properties of BC cells. This pro-metastatic property of normal plasma exosomes may have impact on the course of the disease and on its prognosis.

Variety and Dynamics of Proteoforms in the Human Proteome: Aspects of Markers for Hepatocellular Carcinoma.

We have previously developed an approach, where two-dimensional gel electrophoresis (2DE) was used, followed by sectional analysis of the whole gel using high-resolution nano-liquid chromatography-mass spectrometry (ESI LC-MS/MS). In this study, we applied this approach on the panoramic analysis of proteins and their proteoforms from normal (liver) and cancer (HepG2) cells. This allowed us to detect, in a single proteome, about 20,000 proteoforms coded by more than 4000 genes. A set of 3D-graphs showing distribution of these proteoforms in 2DE maps (profiles) was generated. A comparative analysis of these profiles between normal and cancer cells showed high variability and dynamics of many proteins. Among these proteins, there are some well-known features like alpha-fetoprotein (FETA) or glypican-3 (GPC3) and potential hepatocellular carcinoma (HCC) markers. More detailed information about their proteoforms could be used for generation of panels of more specific biomarkers.