Exosomes, Deep Sequencing, and Biomarker Potential

At the 2013 annual International Society for Extracellular Vesicles (ISEV) (http://www.isevmeeting.org/) conference held in Boston, April 17-20, Michiel Pegtel, Ph.D., Immunologist in the Pathology Department at the VU University Medical Center in Amsterdam, The Netherlands, gave an oral presentation describing how comprehensive deep sequencing analysis revealed non-random small RNA incorporation into tumor exosomes and discussed the biomarker potential of these results. Exosomes (image) are tiny subcellular membrane-bound vesicles (30-150 nm in diameter) that are released by a wide variety of normal cell types and cancer cells, and that can carry membrane and cellular proteins, as well as microRNA (miRNA), and various other types of RNA, including mRNA fragments, representative of the cell of origin. It is thought that exosomes may serve the purpose of shuttling information from one cell to another. For instance, it has been shown that exosomes can carry material from cancer cells that acts to suppress the immune system and stimulate angiogenesis, thus encouraging cancer growth. In talking with BioQuick, Dr. Pegtel emphasized the key role of deep sequencing in his work. “In contrast to closed profiling technologies such as microarray and RT-PCR arrays, deep sequencing has literallyy opened our eyes on the complexity of the human transcriptome. Our previous work using individual quantitative RT-PCR could demonstrate that human B cells infected with the tumor virus Epstein Barr (EBV) secrete exosomes that contain fully mature and functional virus-encoded miRNAs. At the ISEV meeting, Nobel laureate Dr. Phillip Sharp stressed the importance of quantitation in RNA research. I could not agree more as this applies directly to research concerning transfer of functional RNA via exosomes.
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