title: PEDF increases the tumoricidal activity of macrophages towards prostate cancer cells in vitro.
abstract: BACKGROUND
  Although inflammation and prostate cancer (PCa) have been linked, the molecular interactions between macrophages and PCa cells are poorly explored. Pigment Epithelium-Derived Factor (PEDF) is an anti-angiogenic and anti-tumor factor. We previously showed that PEDF induces macrophages recruitment in vitro, correlates with macrophages density in human prostate, and stimulates macrophages polarization towards the classically activated pathway. Here, we demonstrate that PEDF modulates the interaction between macrophages and PCa cells through a bidirectional signalling leading to tumor cell apoptosis and phagocytosis.
  
  
  METHODS
  RAW 264.7 and THP-1 cells, and BMDMs were grown in vitro as mono- or co-cultures with PC3 or CL1 tumor cells. The effects of PEDF and its derived P18 peptide were measured on macrophages differentiation, migration, and superoxide production, and tumor cell apoptosis and phagocytosis. PEDF receptors (ATP5B, PNPLA2, and LRP6) and CD47 mRNA and protein expression were quantified in macrophages and tumor cells by quantitative RT-PCR, western blot, immunofluorescence and flow cytometry.
  
  
  RESULTS
  We found that PEDF induced the migration of macrophages towards tumor 3D spheroids and 2D cultures. In co-culture, PEDF increased PCa cells phagocytosis through an indirect apoptosis-dependent mechanism. Moreover, PEDF stimulated the production of superoxide by macrophages. Conditioned media from macrophages exposed to PEDF induced tumor cells apoptosis in contrast to control conditioned media suggesting that ROS may be involved in tumor cells apoptosis. ATP5B and PNPLA2 PEDF receptors on macrophages and CD47 on tumor cells were respectively up- and down-regulated by PEDF. As PEDF, blocking CD47 induced phagocytosis. Inhibiting ATP5B reduced phagocytosis. Inversely, PNPLA2 inhibition blocks differentiation but maintains phagocytosis. CD47-induced phagocytosis was partially reverted by ATP5B inhibition suggesting a complementary action. Similar effects were observed with P18 PEDF-derived peptide.
  
  
  CONCLUSIONS
  These data established that modulating the molecular interactions between macrophages and PCa cells using PEDF may be a promising strategy for PCa treatment.
authors.affiliation: Department of Urology, Texas Tech University-Health Sciences Center, Lubbock, Texas, United States of America.
authors.forename: Dalia
authors.initials: D
authors.lastname: Martinez-Marin
authors.affiliation: Department of Urology, Texas Tech University-Health Sciences Center, Lubbock, Texas, United States of America.|Department of Immunology and Molecular Microbiology, Texas Tech University-Health Sciences Center, Lubbock, Texas, United States of America.
authors.forename: Courtney
authors.initials: C
authors.lastname: Jarvis
authors.affiliation: Department of Urology, Texas Tech University-Health Sciences Center, Lubbock, Texas, United States of America.
authors.forename: Thomas
authors.initials: T
authors.lastname: Nelius
authors.affiliation: Department of Urology, Texas Tech University-Health Sciences Center, Lubbock, Texas, United States of America.
authors.forename: Werner
authors.initials: W
authors.lastname: de Riese
authors.affiliation: Department of Urology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States of America.
authors.forename: Olga V
authors.initials: OV
authors.lastname: Volpert
authors.affiliation: Department of Urology, Texas Tech University-Health Sciences Center, Lubbock, Texas, United States of America.|Department of Immunology and Molecular Microbiology, Texas Tech University-Health Sciences Center, Lubbock, Texas, United States of America.
authors.forename: Stéphanie
authors.identifier: http://orcid.org/0000-0002-3420-5536
authors.initials: S
authors.lastname: Filleur
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D051928:CD47 Antigen / Q000378:metabolism; D045744:Cell Line, Tumor; D002465:Cell Movement; D018920:Coculture Techniques; D004354:Drug Screening Assays, Antitumor; D005136:Eye Proteins / Q000494:pharmacology*; D006801:Humans; D008049:Lipase / Q000378:metabolism; D008264:Macrophages / Q000187:drug effects / Q000502:physiology*; D008297:Male; D051379:Mice; D025261:Mitochondrial Proton-Translocating ATPases / Q000378:metabolism; D009414:Nerve Growth Factors / Q000494:pharmacology*; D010587:Phagocytosis; D010671:Phenylurea Compounds / Q000494:pharmacology; D011471:Prostatic Neoplasms / Q000188:drug therapy*; D000067996:RAW 264.7 Cells; D015843:Serpins / Q000494:pharmacology*; D018874:Spheroids, Cellular / Q000187:drug effects / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D000099174:Pigment Epithelium-Derived Factor; D000217:Acyltransferases
chemical_list: D000970:Antineoplastic Agents; D051928:CD47 Antigen; D005136:Eye Proteins; D008049:Lipase; D025261:Mitochondrial Proton-Translocating ATPases; D009414:Nerve Growth Factors; D010671:Phenylurea Compounds; D015843:Serpins; D013481:Superoxides; D000099174:Pigment Epithelium-Derived Factor; C585749:atglistatin; C494445:PNPLA2 protein, mouse; D000217:Acyltransferases; C530489:ATP5b protein, mouse