Moreover, inhibition of exosome secretion at sites of invadopodia-actin rich structures associated with ECM degradation-lead to impaired cell migration. For example, matrix-bound exosomes have been shown to drive directional cell movement by fostering cell-ECM adhesion assembly. In addition to mediating cell-cell crosstalk, exosomes also actively interact with the ECM and remodel it. Exosome-mediated uptake and/or exchange of bioactive materials including proteins, glycans, metabolites, DNA, RNA, and miRNA mediate both autocrine and paracrine signalling. Exosomes are small, lipid bilayer nanovesicles that contribute to cancer metastasis by enhancing tumor cell migration and invasion, remodelling the extracellular matrix and establishing pre-metastatic niche. The spurt of recent reports identify exosomes as a novel mode intercellular communication that facilitate interplays and rewiring between different components of tumor microenvironment. However, all these studies embodying mechanoresponse explicitly demonstrate the direct effects of ECM stiffening on tumor cells behaviour and there is little evidence revealing the indirect effects of ECM rigidity employing other modes of communication, such as microvesicles or exosomes. Increased ECM stiffness influences a gamut of cellular responses culminating in boosted invasiveness in vitro and metastasis in vivo via integrins and PI3K signalling and increased cell contractility. In breast cancer, tumorigenesis and metastatic progression are often accompanied by increased stiffness of the ECM in and around the tumor caused by excessive collagen deposition, crosslinking and remodelling. The extracellular matrix (ECM) which constitutes the physical component of the tumor milieu, plays an active role in cancer progression. High mortality in breast cancer patients is attributed to metastatic spread of the disease. Our studies establish the pivotal role of exosomal communication in ECM stiffness dependent cell migration with exosomal THBS1 as a master regulator of cancer invasion, which can be further exploited as a potential theranostic for improved breast cancer management. We further demonstrated that exosomal THBS1 mediates these stiffness-induced effects by engaging matrix metalloproteinase and focal adhesion kinase. Knockdown studies confirmed that the pro-invasive effects of stiffness-tuned exosomes are fuelled by exosomal THBS1. Quantitative proteomics of exosomes combined with genomic analysis of human breast tumor tissues (TCGA database) identified thrombospondin-1 (THBS1) as a prospective regulator of stiffness-dependent cancer invasion. Proteomic analysis of exosomal lysates followed by overrepresentation analysis and interactome studies revealed enrichment of cell adhesion and cell migration proteins in exosomes from stiff ECM cultures compared to that of soft ones.
#Ecm tune series#
Reciprocally, exogenous addition of ECM stiffness-tuned exosomes orchestrated a series of changes in cell morphology, adhesion, protrusion dynamics resulting in fostered cell motility and invasion. Interestingly, blocking exosome synthesis and secretion by GW4869 abrogated stiffness regulated motility and contractility in breast cancer cells. Using stiffness tuneable hydrogel ECM scaffolds, we show that stiff ECMs promote exosome secretion in a YAP/TAZ pathway-dependent manner. Here we demonstrate the role of exosomes in ECM stiffness triggered breast cancer invasiveness. The mechanisms by which extracellular matrix (ECM) stiffening drives breast cancer invasion is an area of active research. Breast cancer progression features ECM stiffening due to excess deposition and crosslinking of collagen, which dramatically influence tumor behaviour and fate.