title: Cavin-1/PTRF alters prostate cancer cell-derived extracellular vesicle content and internalization to attenuate extracellular vesicle-mediated osteoclastogenesis and osteoblast proliferation.
abstract: BACKGROUND
  Tumour-derived extracellular vesicles (EVs) play a role in tumour progression; however, the spectrum of molecular mechanisms regulating EV secretion and cargo selection remain to be fully elucidated. We have reported that cavin-1 expression in prostate cancer PC3 cells reduced the abundance of a subset of EV proteins, concomitant with reduced xenograft tumour growth and metastasis.
  
  
  METHODS
  We examined the functional outcomes and mechanisms of cavin-1 expression on PC3-derived EVs (PC3-EVs).
  
  
  RESULTS
  PC3-EVs were internalized by osteoclast precursor RAW264.7 cells and primary human osteoblasts (hOBs) in vitro, stimulating osteoclastogenesis 37-fold and hOB proliferation 1.5-fold, respectively. Strikin gly, EVs derived from cavin-1-expressing PC3 cells (cavin-1-PC3-EVs) failed to induce multinucleate osteoblasts or hOB proliferation. Cavin-1 was not detected in EVs, indicating an indirect mechanism of action. EV morphology, size and quantity were also not affected by cavin-1 expression, suggesting that cavin-1 modulated EV cargo recruitment rather than release. While cavin-1-EVs had no osteoclastogenic function, they were internalized by RAW264.7 cells but at a reduced efficiency compared to control EVs. EV surface proteins are required for internalization of PC3-EVs by RAW264.7 cells, as proteinase K treatment abolished uptake of both control and cavin-1-PC3-EVs. Removal of sialic acid modifications by neuraminidase treatment increased the amount of control PC3-EVs internalized by RAW264.7 cells, without affecting cavin-1-PC3-EVs. This suggests that cavin-1 expression altered the glycosylation modifications on PC3-EV surface. Finally, cavin-1 expression did not affect EV in vivo tissue targeting as both control and cavin-1-PC3-EVs were predominantly retained in the lung and bone 24 hours after injection into mice.
  
  
  CONCLUSIONS
  Taken together, our results reveal a novel pathway for EV cargo sorting, and highlight the potential of utilizing cavin-1-mediated pathways to attenuate metastatic prostate cancer.
authors.affiliation: The University of Queensland Diamantina Institute, The University of Queensland, Translational Research Institute, Brisbane, Australia.
authors.forename: Kerry L
authors.initials: KL
authors.lastname: Inder
authors.affiliation: The University of Queensland Diamantina Institute, The University of Queensland, Translational Research Institute, Brisbane, Australia.
authors.forename: Jayde E
authors.initials: JE
authors.lastname: Ruelcke
authors.affiliation: The University of Queensland Diamantina Institute, The University of Queensland, Translational Research Institute, Brisbane, Australia.
authors.forename: Lara
authors.initials: L
authors.lastname: Petelin
authors.affiliation: The University of Queensland Diamantina Institute, The University of Queensland, Translational Research Institute, Brisbane, Australia.
authors.forename: Hyeongsun
authors.initials: H
authors.lastname: Moon
authors.affiliation: The University of Queensland Diamantina Institute, The University of Queensland, Translational Research Institute, Brisbane, Australia.
authors.forename: Eunju
authors.initials: E
authors.lastname: Choi
authors.affiliation: Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia.
authors.forename: James
authors.initials: J
authors.lastname: Rae
authors.affiliation: The University of Queensland Diamantina Institute, The University of Queensland, Translational Research Institute, Brisbane, Australia ; Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Australia.
authors.forename: Antje
authors.initials: A
authors.lastname: Blumenthal
authors.affiliation: Institute for Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia.
authors.forename: Dietmar
authors.initials: D
authors.lastname: Hutmacher
authors.affiliation: The University of Queensland Diamantina Institute, The University of Queensland, Translational Research Institute, Brisbane, Australia.
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Saunders
authors.affiliation: Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Stow
authors.affiliation: Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia ; Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane, Australia.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Parton
authors.affiliation: The University of Queensland Diamantina Institute, The University of Queensland, Translational Research Institute, Brisbane, Australia.
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Hill
keywords: caveolae; caveolin; exosomes; metastasis; osteoclast; polymerase I and transcript release factor; prostasome