Molecular lipid species in urinary exosomes as potential prostate cancer biomarkers

Exosomes have recently appeared as a novel source of noninvasive cancer biomarkers, since these nanovesicles contain molecules from cancer cells and can be detected in biofluids. We have here investigated the potential use of lipids in urinary exosomes as prostate cancer biomarkers.

A high-throughput mass spectrometry quantitative lipidomic analysis was performed to reveal the lipid composition of urinary exosomes in prostate cancer patients and healthy controls.

Control samples were first analysed to characterise the lipidome of urinary exosomes and test the reproducibility of the method. In total, 107 lipid species were quantified in urinary exosomes. Several differences, for example, in cholesterol and phosphatidylcholine, were found between urinary exosomes and exosomes derived from cell lines, thus showing the importance of in vivo studies for biomarker analysis. The 36 most abundant lipid species in urinary exosomes were then quantified in 15 prostate cancer patients and 13 healthy controls. Interestingly, the levels of nine lipids species were found to be significantly different when the two groups were compared. The highest significance was shown for phosphatidylserine (PS) 18:1/18:1 and lactosylceramide (d18:1/16:0), the latter also showed the highest patient-to-control ratio. Furthermore, combinations of these lipid species and PS 18:0-18:2 distinguished the two groups with 93% sensitivity and 100% specificity. Finally, in agreement with the reported dysregulation of sphingolipid metabolism in cancer cells, alteration in specific sphingolipid lipid classes were observed.

This study shows for the first time the potential use of exosomal lipid species in urine as prostate cancer biomarkers.

European journal of cancer (Oxford, England : 1990). 2016 Jan 30 [Epub ahead of print]

Tore Skotland, Kim Ekroos, Dimple Kauhanen, Helena Simolin, Therese Seierstad, Viktor Berge, Kirsten Sandvig, Alicia Llorente

Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital-The Norwegian Radium Hospital, 0379 Oslo, Norway; Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, 0379 Oslo, Norway., Zora Biosciences Oy, 02150 Espoo, Finland., Division of Radiology and Nuclear Medicine, Oslo University Hospital, 0379 Oslo, Norway., Department of Urology, Oslo University Hospital, 0586 Oslo, Norway., Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital-The Norwegian Radium Hospital, 0379 Oslo, Norway; Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, 0379 Oslo, Norway; Department of Biosciences, University of Oslo, 0316 Oslo, Norway., Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital-The Norwegian Radium Hospital, 0379 Oslo, Norway; Centre for Cancer Biomedicine, Faculty of Medicine, University of Oslo, 0379 Oslo, Norway. Electronic address: .

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