title: Mass spectrometric detection of 27-hydroxycholesterol in breast cancer exosomes.
abstract: Exosomes from cancer cells are rich sources of biomarkers and may contain elevated levels of lipids of diagnostic value. 27-Hydroxycholesterol (27-OHC) is associated with proliferation and metastasis in estrogen receptor positive (ER+) breast cancer. In this study, we investigated the levels of 27-OHC, and other sidechain-hydroxylated oxysterols in exosomes. To study both cytoplasmic and exosomal oxysterol samples of limited size, we have developed a capillary liquid chromatography-mass spectrometry platform that outperforms our previously published systems regarding chromatographic resolution, analysis time and sensitivity. In the analyzed samples, the quantified level of cytoplasmic 27-OHC using this platform fitted with mRNA levels of 27-OHC's corresponding enzyme, CYP27A1. We find clearly increased levels of 27-OHC in exosomes (i.e., enrichment) from an ER+ breast cancer cell line (MCF-7) compared to exosomes derived from an estrogen receptor (ER-) breast cancer cell line (MDA-MB-231) and other control exosomes (non-cancerous cell line (HEK293) and human pooled serum). The exosomal oxysterol profile did not reflect cytoplasmic oxysterol profiles in the cells of origin; cytoplasmic 27-OHC was low in ER+ MCF-7 cells while high in MDA-MB-231 cells. Other control cancer cells showed varied cytoplasmic oxysterol levels. Hence, exosome profiling in cancer cells might provide complementary information with the possibility of diagnostic value.
authors.affiliation: Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, NO-0315 Oslo, Norway. Electronic address: Hanne.roberg-larsen@kjemi.uio.no.
authors.forename: Hanne
authors.initials: H
authors.lastname: Roberg-Larsen
authors.affiliation: Unit for Cell Signaling, Oslo University Hospital, Rikshospitalet, NO-0027 Oslo, Norway.
authors.forename: Kaja
authors.initials: K
authors.lastname: Lund
authors.affiliation: Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, NO-0315 Oslo, Norway.
authors.forename: Kristina Erikstad
authors.initials: KE
authors.lastname: Seterdal
authors.affiliation: Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, NO-0315 Oslo, Norway.
authors.forename: Stian
authors.initials: S
authors.lastname: Solheim
authors.affiliation: Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, NO-0315 Oslo, Norway.
authors.forename: Tore
authors.initials: T
authors.lastname: Vehus
authors.affiliation: Unit for Cell Signaling, Oslo University Hospital, Rikshospitalet, NO-0027 Oslo, Norway.
authors.forename: Nina
authors.initials: N
authors.lastname: Solberg
authors.affiliation: Unit for Cell Signaling, Oslo University Hospital, Rikshospitalet, NO-0027 Oslo, Norway.
authors.forename: Stefan
authors.initials: S
authors.lastname: Krauss
authors.affiliation: Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, NO-0315 Oslo, Norway.
authors.forename: Elsa
authors.initials: E
authors.lastname: Lundanes
authors.affiliation: Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, NO-0315 Oslo, Norway.
authors.forename: Steven Ray
authors.initials: SR
authors.lastname: Wilson
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism*; D045744:Cell Line, Tumor; D002853:Chromatography, Liquid; D003593:Cytoplasm / Q000378:metabolism; D047628:Estrogen Receptor alpha / Q000378:metabolism*; D055354:Exosomes / Q000737:chemistry*; D005260:Female; D057809:HEK293 Cells; D006801:Humans; D006888:Hydroxycholesterols / Q000737:chemistry*; D061986:MCF-7 Cells; D013058:Mass Spectrometry; D015203:Reproducibility of Results
chemical_list: C506487:ESR1 protein, human; D047628:Estrogen Receptor alpha; D006888:Hydroxycholesterols; C076996:27-hydroxycholesterol
keywords: 27-hydroxycholesterol; Breast cancer; Exosome; Oxysterol; Sterolome