Crosstalk between exosomes signaling pathway and autophagy flux in senescent human endothelial cells.

The intracellular endomembrane system contributes to maintaining cell homeostasis. We investigate the dynamic of exosomal and autophagy pathways in Human Umbilical Vein Cells (HUVECs) following incubation with H2O2 in vitro. Cellular senescence was induced to HUVECs using 100 µM H2O2. ELISA and AChE assay was used to calculate the number of exosomes. Exosomes were isolated and characterized by dynamic light scattering, flow cytometry, and SEM. Transcript and protein levels of genes involved in the exosomal and autophagy pathways were measured by real-time PCR (Q-PCR) and western blotting. Subcellular distribution of CD63 was monitored by immunofluorescence microscopy. We also measured the expression of miR-182 and miR-155 by qPCR assay. Results showed that secretion of exosomes was increased in treated cells (p < 0.05). Exosomes were confirmed by size and positive for CD63 marker. Molecular analysis of the exosomal secretory pathway has revealed a significant induction of CD63, CD81, TSAP6, Rab11, Rab27a, and Rab27b in response to H2O2 (p < 0.05). The distribution of CD63 was increased inside treated cells. The western blotting technique revealed a significant up-regulation in Becline-1 and P62 and a significant decrease in LC3 II/I ratio in treated cells (p < 0.05)s. Concomitant with an up-regulation of common molecules in exosomes biogenesis and autophagy including Atg5, P62 and P53, expression of miR-182 decreased and miR-155 increased in cells incubated with H2O2 (p < 0.05). Data suggested an induction in the exosomal secretory pathway coincided with a block in autophagy progress, accelerating senescence, which might be targeted for the treatment of age-related diseases.

Tumor-derived extracellular vesicles: The metastatic organotropism drivers.

The continuous growing, spreading, and metastasis of tumor cells depend on intercellular communication within cells resident in a tissue environment. Such communication is mediated through the secretion of particles from tumor cells and resident cells known as extracellular vesicles (EVs) within a microenvironment. EVs are a heterogeneous population of membranous vesicles released from tumor cells that transfer many types of active biomolecules to recipient cells and induce physiologic and phenotypic alterations in the tissue environment. Spreading the 'seeds' of metastasis needs the EVs that qualify the 'soil' at distant sites to promote the progress of arriving tumor cells. Growing evidence indicates that EVs have vital roles in tumorigenesis, including pre-metastatic niche formation and organotropic metastasis. These EVs mediate organotropic metastasis by modifying the pre-metastatic microenvironment through different pathways including induction of phenotypic alternation and differentiation of cells, enrolment of distinct supportive stromal cells, up-regulation of the expression of pro-inflammatory genes, and induction of immunosuppressive status. However, instead of pre-metastatic niche formation, evidence suggests that EVs may mediate reawakening of dormant niches. Findings regarding EVs function in tumor metastasis have led to growing interests in the interdisciplinary significance of EVs, including targeted therapy, cell-free therapy, drug-delivery system, and diagnostic biomarker. In this review, we discuss EVs-mediated pre-metastatic niche formation and organotropic metastasis in visceral such as lung, liver, brain, lymph node, and bone with a focus on associated signaling, causing visceral environment hospitable for metastatic cells. Furthermore, we present an overview of the possible therapeutic application of EVs in cancer management.