Exosome Proteome of U-87MG Glioblastoma Cells

Abstract

Exosomes are small membrane vesicles between 30 and 100 nm in diameter secreted by many cell types, and are associated with a wide range of physiological and/or pathological processes. Exosomes containing proteins, lipids, mRNA, and microRNA contribute to cell-to-cell communication and cell-to-environment regulation, however, their biological functions are not yet fully understood. In this report, exosomes in the glioblastoma cell line, U-87MG, were isolated and the proteome was investigated. In addition, exosome proteome changes in U-87MG cells exposed to a low temperature were investigated to elucidate whether the exosome proteome could respond to an external stimulus. Cell culture medium was collected, and exosomes were isolated by continuous centrifugation eliminating cell debris, nucleic acids, and other particles. The morphology of exosomes was observed by cryo-tunneling electron microscopy. According to 2-dimensional electrophoresis and matrix-assisted laser desorption ionization time-of-flight mass spectrometry, certain proteins including collagen type VI alpha 1, putative RNA-binding protein 15B chain A, substrate induced remodeling of the active site regulates HTRA1, coatomer protein complex-subunit beta 2, myosin-heavy chain 1, and keratin-type I cytoskeletal 9 showed differences between the control proteome and the low temperature-exposed proteome.

Glioma-derived exosomes drive the differentiation of neural stem cells to astrocytes

“…The supernatant media was then centrifuged at 150,000 g for 3-4 h. After centrifugation, the supernatant was discarded, and the pellet was resuspended in PBS for further analysis of exosomes with the same protein concentrations across samples (0.2 μg/μL). The proteomic and the cellular gene expression of these exosomes have been published previously [26,27,28,29,30,31]. We characterized the size and number of exosomes in our samples using the nanoparticle tracking analysis (NTA, ZetaView PMX120).…”

Structure-to-Efficacy Relationship of HPMA-Based Nanomedicines: The Tumor Spheroid Penetration Study

“…For the pH-sensitive polymer conjugates, it was postulated that the drug is liberated upon exposure to the low pH in endosomes, then transferred as a free drug via exosomes to other cells. We hypothesize that a similar course can occur in the case of penetration of pH-sensitive THP-polymer conjugates in U87-MG spheroids, which are known to form exosomes massively [ 35 ]. The endocytosed polymer conjugate is freed of THP, then transferred via exosomes to invade the next layer of the cells in the spheroid, thereby leading to the more pronounced penetration based on the combined penetration of bound and released THP.…”

Exosomal Chaperones and miRNAs in Gliomagenesis: State-of-Art and Theranostics Perspectives

“…The proteins are involved in pathways for remodeling of ECM, biological adhesion, developmental processes, and progression of inflammation, leading to cancer growth [ 95 ]. Among the proteins that were detected in exosomes produced from glioma cells, we can mention the coatomer protein complex subunit; collagen type VI; myosin heavy chain 1; keratin; annexin A1, A2, A4, A5, A6, A11; Ras-related protein 10 (Rab10), Rab7a, Rab5c; type I collagen and type VI alpha 1 collagen; integrins (β1, α3, αV); CD44; and different kinds of tubulins and actinins [ 96 , 97 ]. The surface of exosomes isolated from GBM cells present the specific mutant epidermal growth factor receptor variant III (EGFRvIII), which is the best known and most specific protein marker for GBM [ 98 ].…”

“…It is likely that extracellular Hsps participate in immune system stimulation or, on the other hand, they may favor tumor escaping from immune reaction. Hsp participation in cell-to-cell crosstalk [ 74 , 96 ] is made possible by their being on the exosome’s surface, and being secreted by both normal and tumor cells [ 109 ]. Hence, Hsps may be important for intercellular cross talk, and when present on the exosome surface, can enhance the activity of the immune system [ 2 , 71 , 72 , 110 ].…”