Year: 2013
Type: dissertation
Abstract: Exosomes are nano-sized extracellular vesicles of endocytic origin participating in cell-to-cell\ncommunication, partly by the transfer of exosomal RNA between cells. These extracellular\nvesicles are released by most cells and found in many body fluids including plasma and urine.\nExosomes differ compared to their donor cells in RNA, protein and lipid composition, and\ntheir molecular content has shown prognostic and diagnostic potential. Uveal melanoma is a\ntumour arising from melanocytes of the eye and despite successful control of the primary\ntumour, approximately one third of the patients will develop metastases, predominantly liver\nmetastases, with poor prognosis. The overall aim of this thesis was to evaluate the role of\nexosomes in cell-to-cell communication and the biological role of exosomal RNA. \nExosomal RNA has been extracted by different RNA isolation methods and we identified that\nthe RNA size distribution pattern varied in multiple studies. Therefore, we aimed to determine\nif this RNA variation was a true variation or merely a consequence of the RNA extraction\nmethod used. We evaluated seven different RNA isolation methods using a mouse mast cell\nline (MC/9) that continuously releases exosomes. The results showed that the exosomal RNA\nyield and size distribution pattern differed substantially between different RNA isolation\nmethods. \nThe mRNA content and function of MC/9 cell-derived exosomes was shown to be altered\ndepending on the culture conditions of the cells. Cells exposed to oxidative stress were shown\nto have the capacity to send a conditioning signal to other cells, resulting in resistance to\noxidative stress in the recipient cells. Moreover, this conditioning signal was shown to be\neradicated upon UV-C exposure, indicating a possible role for the exosomal RNA in this\nbiological function.\nThe presence of exosomes in patients with liver metastases from uveal melanoma was\nestablished with the isolation, detection and characterisation of exosomes from isolated\nhepatic perfusion. The results revealed melanoma-specific exosomes, which contained similar\nmicroRNA profiles between patients. Furthermore, patients with metastatic uveal melanoma\nwere shown to have a higher concentration of exosomes in their peripheral venous blood\ncompared to healthy controls.\nWe conclude that exosomes play a role in cell-to-cell communication and their RNA appears\nto be of biological importance. Furthermore, exosomal RNA may potentially play a role in the\ndiagnosis and prognosis of uveal melanoma.
Author: Maria Eldh
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2609949532