Colocalisation of CD9 and mortalin in CD9-induced mitotic catastrophe in human prostate cancer cells

Advances in exosome analysis

There is growing demand for novel biomarkers that detect early stage disease as well as monitor clinical management and therapeutic strategies. Exosome analysis could provide the next advance in attaining that goal. Exosomes are membrane encapsulated biologic nanometric-sized particles of endocytic origin which are released by all cell types. Unfortunately, exosomes are exceptionally challenging to characterize with current technologies. Exosomes are between 30 and 200nm in diameter, a size that makes them out of the sensitivity range to most cell-oriented sorting or analysis platforms, i.e., traditional flow cytometers. The most common methods for targeting exosomes to date typically involve purification followed by the characterization and the specific determination of their cargo. The whole procedure is time consuming, requiring thus skilled personnel as well as laboratory facilities and benchtop instrumentation. The most relevant methodology for exosome isolation, characterization and quantification is addressed in this chapter, including the most up-to-date approaches to explore the potential usefulness of exosomes as biomarkers in liquid biopsies and in advanced nanomedicine.

Extracellular Vesicle-Mediated Bone Remodeling and Bone Metastasis: Implications in Prostate Cancer

Bone metastasis is the tendency of certain primary tumors to spawn and dictate secondary neoplasia in the bone. The process of bone metastasis is regulated by the dynamic crosstalk between metastatic cancer cells, cellular components of the bone marrow microenvironment (osteoblasts, osteoclasts, and osteocytes), and the bone matrix. The feed-forward loop mechanisms governs the co-option of homeostatic bone remodeling by cancer cells in bone. Recent developments have highlighted the discovery of extracellular vesicles (EVs) and their diverse roles in distant outgrowths. Several studies have implicated EV-mediated interactions between cancer cells and the bone microenvironment in synergistically promoting pathological skeletal metabolism in the metastatic site. Nevertheless, the potential role that EVs serve in arbitrating intricate sequences of coordinated events within the bone microenvironment remains an emerging field. In this chapter, we review the role of cellular participants and molecular mechanisms in regulating normal bone physiology and explore the progress of current research into bone-derived EVs in directly triggering and coordinating the processes of physiological bone remodeling. In view of the emerging role of EVs in interorgan crosstalk, this review also highlights the multiple systemic pathophysiological processes orchestrated by the EVs to direct organotropism in bone in prostate cancer. Given the deleterious consequences of bone metastasis and its clinical importance, in-depth knowledge of the multifarious role of EVs in distant organ metastasis is expected to open new possibilities for prognostic evaluation and therapeutic intervention for advanced bone metastatic prostate cancer.

Matrix Effect in the Isolation of Breast Cancer-Derived Nanovesicles by Immunomagnetic Separation and Electrochemical Immunosensing-A Comparative Study

Exosomes are cell-derived nanovesicles released into biological fluids, which are involved in cell-to-cell communication. The analysis of the content and the surface of the exosomes allow conclusions about the cells they are originating from and the underlying condition, pathology or disease. Therefore, the exosomes are currently considered good candidates as biomarkers to improve the current methods for clinical diagnosis, including cancer. However, due to their low concentration, conventional procedures for exosome detection including biosensing usually require relatively large sample volumes and involve preliminary purification and preconcentration steps by ultracentrifugation. In this paper, the immunomagnetic separation is presented as an alternative method for the specific isolation of exosomes in serum. To achieve that, a rational study of the surface proteins in exosomes, which can be recognized by magnetic particles, is presented. The characterization was performed in exosomes obtained from cell culture supernatants of MCF7, MDA-MB-231 and SKBR3 breast cancer cell lines, including TEM and nanoparticle tracking analysis (NTA). For the specific characterization by flow cytometry and confocal microscopy, different commercial antibodies against selected receptors were used, including the general tetraspanins CD9, CD63 and CD81, and cancer-related receptors (CD24, CD44, CD54, CD326 and CD340). The effect of the serum matrix on the immunomagnetic separation was then carefully evaluated by spiking the exosomes in depleted human serum. Based on this study, the exosomes were preconcentrated by immunomagnetic separation on antiCD81-modified magnetic particles in order to achieve further magnetic actuation on the surface of the electrode for the electrochemical readout. The performance of this approach is discussed and compared with classical characterization methods.

Evolving paradigms on the interplay of mitochondrial Hsp70 chaperone system in cell survival and senescence

The role of mitochondria within a cell has grown beyond being the prime source of cellular energy to one of the major signaling platforms. Recent evidence provides several insights into the crucial roles of mitochondrial chaperones in regulating the organellar response to external triggers. The mitochondrial Hsp70 (mtHsp70/Mortalin/Grp75) chaperone system plays a critical role in the maintenance of proteostasis balance in the organelle. Defects in mtHsp70 network result in attenuated protein transport and misfolding of polypeptides leading to mitochondrial dysfunction. The functions of Hsp70 are primarily governed by J-protein cochaperones. Although human mitochondria possess a single Hsp70, its multifunctionality is characterized by the presence of multiple specific J-proteins. Several studies have shown a potential association of Hsp70 and J-proteins with diverse pathological states that are not limited to their canonical role as chaperones. The role of mitochondrial Hsp70 and its co-chaperones in disease pathogenesis has not been critically reviewed in recent years. We evaluated some of the cellular interfaces where Hsp70 machinery associated with pathophysiological conditions, particularly in context of tumorigenesis and neurodegeneration. The mitochondrial Hsp70 machinery shows a variable localization and integrates multiple components of the cellular processes with varied phenotypic consequences. Although Hsp70 and J-proteins function synergistically in proteins folding, their precise involvement in pathological conditions is mainly idiosyncratic. This machinery is associated with a heterogeneous set of molecules during the progression of a disorder. However, the precise binding to the substrate for a specific physiological response under a disease subtype is still an undocumented area of analysis.

CD9 monoclonal antibody-conjugated PEGylated liposomes for targeted delivery of rapamycin in the treatment of cellular senescence

Premature cellular senescence refers to the state of irreversible cell cycle arrest due to DNA damage or other stresses. In this study, CD9 monoclonal antibody (CD9mAb) was successfully conjugated to the surface of PEGylated liposomes for targeted delivery of rapamycin (LR-CD9mAb) to overcome senescence of CD9 receptor-overexpressing cells. LR-CD9mAb has a small particle size (143.3 ± 2.4 nm), narrow size distribution (polydispersity index: 0.220 ± 0.036), and negative zeta potential (-14.6 ± 1.2 mV). The uptake of CD9-targeted liposomes by premature senescent human dermal fibroblasts (HDFs) was higher than that by young HDFs, as displayed by confocal microscopic images. The senescence might not be reversed by treatment with rapamycin; however, the drug promoted cell proliferation and reduced the number of cells that expressed the senescence-associated-β-galactosidase (SA-β-gal). These effects were further confirmed by cell viability, cell cycle, and Western blotting analyses. Moreover, CD9-targeted liposomes showed better anti-senescence activity, in comparison with free rapamycin or the conventional liposomal formulation, suggesting the potential application of this system in further in vivo studies.

Quantitative proteomic study of human prostate cancer cells with different metastatic potentials

Metastatic dissemination is a feature of most cancers including prostate cancer (PCa), and is the main cause of treatment failure and mortality. The aim of the study is to explore the mechanisms of PCa metastasis and to search for potential prognostic markers using proteomics. Two-dimensional fluorescent differential gel electrophoresis (2D-DIGE) was used to quantify proteins in normal prostate epithelial cells, bone metastasis-derived PC-3 cells, and visceral metastasis-derived PC-3M cells. Metastatic potential was confirmed by flow cytometry, electron microscopy, proliferating cell nuclear antigen assay, and wound healing assay. Differential protein expression was compared between PCa cells with different metastatic potentials (LNcap, DU145, PC-3 and PC-3M) and normal prostate epithelial cells (RWPE-1). Selected candidate proteins in human prostate tissues were analyzed using GOA, UniProt and GeneCards analyses. Eighty-six proteins were differentially expressed between cell lines (>1.5-fold, P<0.05). Among them, twelve proteins were identified by MALDI-TOF-MS. One protein was upregulated in normal prostate epithelial cells, nine proteins were upregulated in PC-3, and two proteins were upregulated in PC-3M. Proteins were divided into five groups according to their functions. The SETDB1 protein was closely associated with the prognosis of PCa. Bioinformatics suggested that SETDB1 might promote PCa bone metastasis through the WNT pathway. In conclusion, SETDB1 might be associated with the development of bone metastases from PCa. Further study is necessary to assess its exact role in PCa.

Immuno-based detection of extracellular vesicles in urine as diagnostic marker for prostate cancer

Extracellular vesicles (including the subclass exosomes) secreted by cells contain specific proteins and RNA that could be of interest in determining new markers. Isolation/characterization of PCa-derived exosomes from bodily fluids enables us to discover new markers for this disease. Unfortunately, isolation with current techniques (ultracentrifugation) is labor intensive and other techniques are still under development. The goal of our study was to develop a highly sensitive time-resolved fluorescence immunoassay (TR-FIA) for capture/detection of PCa-derived exosomes. In our assay, biotinylated capture antibodies against human CD9 or CD63 were incubated on streptavidin-coated wells. After application of exosomes, Europium-labeled detection antibodies (CD9 or CD63) were added. Cell medium from 37 cell lines was taken to validate this TR-FIA. Urine was collected (after digital rectal exam) from patients with PCa (n = 67), men without PCa (n = 76). As a control, urine was collected from men after radical prostatectomy (n = 13), women (n = 16) and patients with prostate cancer without digital rectal exam (n = 16). Signal intensities were corrected for urinary PSA and creatinine. This TR-FIA can measure purified exosomes with high sensitivity and minimal background signals. Exosomes can be measured in medium from 37 cell lines and in urine. DRE resulted in a pronounced increase in CD63 signals. After DRE and correction for urinary PSA, CD9 and CD63 were significantly higher in men with PCa. This TR-FIA enabled us to measure exosomes with high sensitivity directly from urine and cell medium. This TR-FIA forms the basis for testing different antibodies directed against exosome membrane markers to generate disease-specific detection assays.

Role of motility-related protein-1 in promoting the development of several types of cancer (Review)

Motility-related protein-1 (CD9), a type of cell surface glycoprotein comprising a four-pass transmembrane domain that forms multimeric complexes with other cell surface proteins, belongs to the tetraspanins family. From previous studies, we know that CD9 is considered to function primarily as a progression and metastasis suppressor in a variety of cancers, including breast, non-small cell lung colon and myeloma. However, an expanding body of literature has shown the contradictory outcome that tetraspanin CD9 is also vital in promoting cancer progression in several types of cancer. This review summarizes the recent studies on CD9 and concludes that it does not always act as a progression and metastasis suppressor. Conversely, in specific cases, CD9 may promote tumor progression through the following three aspects: Facilitating tumor cell transmigration, increasing tumor cell motility and hastening the growth of some cancers. In addition, CD9 appears to be an important marker of cancer stem cells in certain types of tumor.

Down-regulation of CD9 expression and its correlation to tumor progression in B lymphomas

Histological transformation, a pivotal event in the natural history of cancers including lymphomas, is typically associated with more aggressive clinical behavior. L3055, a B lymphoma cell line of germinal center (GC) origin, is dependent on follicular dendritic cells (FDCs) for survival and proliferation, similar to GC-B cells. However, L3055 cells become less FDC-dependent after prolonged culture, which is analogous to transformation in vivo. Comparison of two L3055 subclones (i.e., the FDC-dependent indolent clone 12 and the FDC-independent aggressive clone 33) by DNA microarray revealed that CD9 was the most differentially expressed gene (P = 0.05). L3055-12 expresses high levels of CD9 while L3055-33 does not. Reduced levels or loss of CD9 expression is also observed in other CD9-positive B lymphoma cell lines. The resultant CD9-negative cells grow faster than CD9-positive cells due to their greater resistance to apoptosis. Furthermore, CD9-negative cells are less dependent on FDCs for their survival and growth compared with CD9-positive cells. CD9 down-regulation in B lymphomas appears to be controlled epigenetically, mainly through histone modifications. These findings imply that CD9 is inversely correlated with B lymphoma progression, and CD9 inactivation may play an important role in B lymphoma transformation.