title: Efferocytosis of apoptotic human papillomavirus-positive cervical cancer cells by human primary fibroblasts.
abstract: BACKGROUND
  Efficient clearance of apoptotic cells, named efferocytosis, is a fundamental physiological process for tissue development and homeostasis. The contribution of non-professional phagocytes like fibroblasts to efferocytosis has been established, although the underlying mechanisms are not well understood. We recently demonstrated that horizontal DNA transfer can occur through the uptake of apoptotic human papillomavirus-positive cancer cells by human primary fibroblasts leading to their transformation. The aim of this present study was to analyse the cellular and molecular mechanisms that drive the phagocytic activity of human primary fibroblasts in the context of apoptotic cervical cancer cell removal.
  
  
  RESULTS
  Here we provide evidence that human primary fibroblasts engulf late more efficiently than early apoptotic cells, but their phagocytic ability remains limited compared to professional phagocytes such as human monocyte-derived macrophages. The engulfment occurs in a time-, temperature- and calcium-dependent manner. Remodelling of actin-fibers contributes to the biogenesis of apoptotic cell containing macroendocytic vacuoles. Both morphological analyses and pharmacological approaches confirmed the involvement of actin-driven phagocytosis and likely macropinocytotic mechanisms in apoptotic target internalization. The uptake of apoptotic cells requires phosphatidylserine recognition, which is mainly mediated by phosphatidylserine-receptor brain-specific angiogenesis inhibitor 1. Confocal microscopy analyses with organelle-specific markers revealed that internalised apoptotic material traffics into late phagolysosomes and specific features of microtubule-associated protein 1 light chain 3-associated phagocytosis were observed.
  
  
  CONCLUSIONS
  Our in vitro data show that fibroblasts contribute to apoptotic tumour cell removal by phagocytosis and likely macropinocytotic mechanisms. Efferocytosis by fibroblasts involves phosphatidylserine receptor brain-specific angiogenesis inhibitor 1, which participates in subsequent uptake orchestration via actin cytoskeleton remodelling.
  
  
  CONCLUSIONS
  Our results highlight the cellular and molecular mechanisms of fibroblast-mediated clearance of apoptotic tumour cells. Consequences regarding alternative mechanism of carcinogenesis or tumour progression should be addressed.
authors.affiliation: EA3181, SFR FED4234, Université de Franche-Comté, COMUE Université Bourgogne Franche-Comté, LabEx LipSTIC ANR-11-LABX-0021, F-25030, Besançon Cedex, France.
authors.forename: François
authors.initials: F
authors.lastname: Hermetet
authors.affiliation: EA3181, SFR FED4234, Université de Franche-Comté, COMUE Université Bourgogne Franche-Comté, LabEx LipSTIC ANR-11-LABX-0021, F-25030, Besançon Cedex, France.|Signalling Programme, The Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT, U.K.
authors.forename: Elise
authors.initials: E
authors.lastname: Jacquin
authors.affiliation: EA3181, SFR FED4234, Université de Franche-Comté, COMUE Université Bourgogne Franche-Comté, LabEx LipSTIC ANR-11-LABX-0021, F-25030, Besançon Cedex, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Launay
authors.affiliation: EA3181, SFR FED4234, Université de Franche-Comté, COMUE Université Bourgogne Franche-Comté, LabEx LipSTIC ANR-11-LABX-0021, F-25030, Besançon Cedex, France.
authors.forename: Emilie
authors.initials: E
authors.lastname: Gaiffe
authors.affiliation: UMR 1098, INSERM, Etablissement Français du Sang Bourgogne Franche-Comté, Université de Franche-Comté, COMUE Université Bourgogne Franche-Comté, SFR FED4234, LabEx LipSTIC ANR-11-LABX-0021, BP 1937, F-25020, Besançon Cedex, France.
authors.forename: Mélanie
authors.initials: M
authors.lastname: Couturier
authors.affiliation: EA3181, SFR FED4234, Université de Franche-Comté, COMUE Université Bourgogne Franche-Comté, LabEx LipSTIC ANR-11-LABX-0021, F-25030, Besançon Cedex, France.
authors.forename: Fabienne
authors.initials: F
authors.lastname: Hirchaud
authors.affiliation: UMR 6174, Institut FEMTO-ST, CNRS, Université de Franche-Comté, COMUE Université Bourgogne Franche-Comté, F-25044, Besançon Cedex, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Sandoz
authors.affiliation: EA3181, SFR FED4234, Université de Franche-Comté, COMUE Université Bourgogne Franche-Comté, LabEx LipSTIC ANR-11-LABX-0021, F-25030, Besançon Cedex, France.|Centre Hospitalier Régional Universitaire, F-25030, Besançon Cedex, France.
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Prétet
authors.affiliation: EA3181, SFR FED4234, Université de Franche-Comté, COMUE Université Bourgogne Franche-Comté, LabEx LipSTIC ANR-11-LABX-0021, F-25030, Besançon Cedex, France.|Centre Hospitalier Régional Universitaire, F-25030, Besançon Cedex, France.
authors.forename: Christiane
authors.initials: C
authors.lastname: Mougin
mesh_terms: D000328:Adult; D017209:Apoptosis; D005260:Female; D005347:Fibroblasts / Q000378:metabolism* / Q000473:pathology; D006367:HeLa Cells; D006801:Humans; D008875:Middle Aged; D027383:Papillomaviridae; D002583:Uterine Cervical Neoplasms / Q000378:metabolism* / Q000473:pathology / Q000821:virology*
keywords: Apoptotic cancer cell; Brain-specific angiogenesis inhibitor 1; Efferocytosis; Human primary fibroblast; Macropinocytotic mechanism