Methods to Study Integrin Functions on Exosomes

Unlocking Exosome-Based Theragnostic Signatures: Deciphering Secrets of Ovarian Cancer Metastasis

Ovarian cancer (OC) is a common gynecological cancer worldwide. Unfortunately, the lack of early detection methods translates into a substantial cohort of women grappling with the pressing health crisis. The discovery of extracellular vesicles (EVs) (their major subpopulation exosomes, microvesicles, and apoptotic bodies) has provided new insights into the understanding of cancer. Exosomes, a subpopulation of EVs, play a crucial role in cellular communication and reflect the cellular status under both healthy and pathological conditions. Tumor-derived exosomes (TEXs) dynamically influence ovarian cancer progression by regulating uncontrolled cell growth, immune suppression, angiogenesis, metastasis, and the development of drug and therapeutic resistance. In the field of OC diagnostics, TEXs offer potential biomarkers in various body fluids. On the other hand, exosomes have also shown promising abilities to cure ovarian cancer. In this review, we address the interlink between exosomes and ovarian cancer and explore their theragnostic signature. Finally, we highlight future directions of exosome-based ovarian cancer research.

Comparative Analyses of Human Exosome Proteomes

Exosomes are responsible for cell-to-cell communication and serves as a valuable drug delivery vehicle. However, exosome heterogeneity, non-standardized isolation methods and proteomics/bioinformatics approaches limit its clinical applications. To better understand exosome heterogeneity, biological function and molecular mechanism of its biogenesis, secretion and uptake, techniques in proteomics or bioinformatics were applied to investigate human embryonic kidney cell (293T cell line)-derived exosome proteome and enable an integrative comparison of exosomal proteins and protein-protein interaction (PPI) networks of eleven exosome proteomes extracted from diverse human samples, including 293T (two datasets), dermal fibroblast, mesenchymal stem cell, thymic epithelial primary cell, breast cancer cell line (MDA-MB-231), patient neuroblastoma cell, plasma, saliva, serum and urine. Mapping of exosome biogenesis/secretion/uptake-related proteins onto exosome proteomes highlights exosomal origin-specific routes of exosome biogenesis/secretion/uptake and exosome-dependent intercellular communication. The finding provides insight into comparative exosome proteomes and its biogenesis, secretion and uptake, and potentially contributes to clinical applications.

Integrin-Mediated Exosomal Homing to Organs

Exosomes, the small extracellular vesicles of 40-150 nm in size, are secreted by nearly all types of cells and play a dynamic role in intercellular and interorgan communications. These vesicles secreted by source cells contain a variety of biologically active materials such as microRNAs (miRNAs) or proteins, thereby utilizing these cargoes in modifying molecular functionalities of the target cells in the remote tissues. Consequently, several key functions of microenvironmental niches in the tissues are regulated in an exosome-dependent manner. The precise mechanisms by which the exosomes bind and home to different organs remained largely unknown. In recent years, integrins, a large family of cell adhesion molecules, have been revealed to play a crucial role in guiding homing of exosomes to target tissues, as integrins regulate tissue-specific homing of cells. In this regard, it is imperative to experimentally determine the roles played by integrins on the exosomes in their tissue-specific homing. This chapter presents a protocol to investigate exosomal homing regulated by integrins in in vitro and in vivo settings. We focus on β7 integrin, as its role in mediating the gut-specific homing of lymphocytes has been well established.

miRNA-200c-3p targets talin-1 to regulate integrin-mediated cell adhesion

The ability of integrins on the cell surface to mediate cell adhesion to the extracellular matrix ligands is regulated by intracellular signaling cascades. During this signaling process, the talin (TLN) recruited to integrin cytoplasmic tails plays the critical role of the major adaptor protein to trigger integrin activation. Thus, intracellular levels of TLN are thought to determine integrin-mediated cellular functions. However, the epigenetic regulation of TLN expression and consequent modulation of integrin activation remain to be elucidated. Bioinformatics analysis led us to consider miR-200c-3p as a TLN1-targeting miRNA. To test this, we have generated miR-200c-3p-overexpressing and miR-200c-3p-underexpressing  cell lines, including HEK293T, HCT116, and LNCaP cells. Overexpression of miR-200c-3p resulted in a remarkable decrease in the expression of TLN1, which was associated with the suppression of integrin-mediated cell adhesion to fibronectin. In contrast, the reduction in endogenous miR-200c-3p levels led to increased expression of TLN1 and enhanced cell adhesion to fibronectin and focal adhesion plaques formation. Moreover, miR-200c-3p was found to target TLN1 by binding to its 3′-untranslated region (UTR). Taken together, our data indicate that miR-200c-3p contributes to the regulation of integrin activation and cell adhesion via the targeting of TLN1.