title: Exosomal particles secreted by prostate cancer cells are potent mRNA and protein vehicles for the interference of tumor and tumor environment.
abstract: BACKGROUND
  Remodeling of the tumor environment and the modulation of tumor associated non-malignant cells are essential events in tumor progression. Exosomes are small membranous vesicles of 50-150 nm in diameter, which are secreted into the extracellular space and supposedly serve as vehicles for signal and effector molecules to modulate adjacent target cells. We characterized the mRNA and protein composition as well as cellular functions of prostate cancer cell-derived exosomes.
  
  
  METHODS
  Exosomes were prepared from prostate cancer cell culture supernatant by ultracentrifugation and subsequently characterized by dynamic light scattering and electron microscopy. Exosomal mRNA and protein composition were analyzed by DNA microarrays and gel electrophoresis coupled with mass spectrometry. Physiological effects of exosomes were studied by means of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and lactate dehydrogenase release cell assays. Using a SILAC approach, putative uptake of exosomal human proteins in canine cells and canine de novo synthesis of proteins specified by exosome-transferred human mRNA was analyzed in MDCK cells via mass spectrometry.
  
  
  RESULTS
  Preparations of exosomes revealed typical cup shaped particles of 150 nm in diameter. Analysis of mRNA and protein composition of exosomes exhibited a wide range of mRNA and protein species. Interestingly, the packaging of at least small proteins into exosomes was apparently unspecific, as shown with the example of two model proteins. In cell culture incubation experiments exosomal preparations of prostate cancer cells caused anti-proliferative effects. MS analysis revealed the uptake of exosomal human proteins into canine cells after 6 hr of incubation.
  
  
  CONCLUSIONS
  The results reveal a distinct exosomal functionality in the modulation of the prostatic tumor adjacent environment. The multitude of translocated factors implies the induction of numerous effects in tumor-associated target cells, including impact on cellular growth.
authors.affiliation: Department of Urology, University Medicine Greifswald, Greifswald, Germany.
authors.forename: Lisa
authors.initials: L
authors.lastname: Rauschenberger
authors.affiliation: Department of Urology, University Medicine Greifswald, Greifswald, Germany.
authors.forename: Doreen
authors.initials: D
authors.lastname: Staar
authors.affiliation: Department of Pharmacology, Center of Drug Absorption and Transport (C_DAT), University Medicine Greifswald, Greifswald, Germany.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Thom
authors.affiliation: Department of Otorhinolaryngology, Head and Neck Surgery, University Medicine Greifswald, Greifswald, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Scharf
authors.affiliation: Department of Medical Biochemistry and Molecular Biology, University Medicine Greifswald, Greifswald, Germany.
authors.forename: Simone
authors.initials: S
authors.lastname: Venz
authors.affiliation: Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Homuth
authors.affiliation: Institute of Microbiology, Ernst Moritz Arndt University Greifswald, Greifswald, Germany.
authors.forename: Rabea
authors.initials: R
authors.lastname: Schlüter
authors.affiliation: Department of Anatomy and Cell Biology, RWTH Aachen University, Aachen, Germany.
authors.forename: Lars-Ove
authors.initials: LO
authors.lastname: Brandenburg
authors.affiliation: Department of Occupational and Social Medicine, RWTH Aachen University, Aachen, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Ziegler
authors.affiliation: Department of Urology, University Medicine Greifswald, Greifswald, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Zimmermann
authors.affiliation: Department of Pharmacology, Center of Drug Absorption and Transport (C_DAT), University Medicine Greifswald, Greifswald, Germany.
authors.forename: Werner
authors.initials: W
authors.lastname: Weitschies
authors.affiliation: Department of Otorhinolaryngology, Head and Neck Surgery, University Medicine Greifswald, Greifswald, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Völker
authors.affiliation: Department of Medical Biochemistry and Molecular Biology, University Medicine Greifswald, Greifswald, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Lendeckel
authors.affiliation: Department of Medical Biochemistry and Molecular Biology, University Medicine Greifswald, Greifswald, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Walther
authors.affiliation: Department of Urology, University Medicine Greifswald, Greifswald, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Burchardt
authors.affiliation: Department of Urology, University Medicine Greifswald, Greifswald, Germany.
authors.forename: Matthias B
authors.initials: MB
authors.lastname: Stope
mesh_terms: D000818:Animals; D002450:Cell Communication / Q000502:physiology; D045744:Cell Line, Tumor; D004285:Dogs; D000067493:Dynamic Light Scattering; D055354:Exosomes / Q000502:physiology* / Q000648:ultrastructure; D057809:HEK293 Cells; D006801:Humans; D061985:Madin Darby Canine Kidney Cells; D008297:Male; D046529:Microscopy, Electron, Transmission; D010316:Particle Size; D011471:Prostatic Neoplasms / Q000648:ultrastructure*; D021381:Protein Transport / Q000502:physiology; D011506:Proteins / Q000032:analysis / Q000378:metabolism*; D034443:RNA Transport / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism*; D059016:Tumor Microenvironment
chemical_list: D011506:Proteins; D012333:RNA, Messenger
keywords: exosomes; microenvironment; prostate cancer; protein uptake