title: A novel pathway combining calreticulin exposure and ATP secretion in immunogenic cancer cell death.
abstract: Surface-exposed calreticulin (ecto-CRT) and secreted ATP are crucial damage-associated molecular patterns (DAMPs) for immunogenic apoptosis. Inducers of immunogenic apoptosis rely on an endoplasmic reticulum (ER)-based (reactive oxygen species (ROS)-regulated) pathway for ecto-CRT induction, but the ATP secretion pathway is unknown. We found that after photodynamic therapy (PDT), which generates ROS-mediated ER stress, dying cancer cells undergo immunogenic apoptosis characterized by phenotypic maturation (CD80(high), CD83(high), CD86(high), MHC-II(high)) and functional stimulation (NO(high), IL-10(absent), IL-1β(high)) of dendritic cells as well as induction of a protective antitumour immune response. Intriguingly, early after PDT the cancer cells displayed ecto-CRT and secreted ATP before exhibiting biochemical signatures of apoptosis, through overlapping PERK-orchestrated pathways that require a functional secretory pathway and phosphoinositide 3-kinase (PI3K)-mediated plasma membrane/extracellular trafficking. Interestingly, eIF2α phosphorylation and caspase-8 signalling are dispensable for this ecto-CRT exposure. We also identified LRP1/CD91 as the surface docking site for ecto-CRT and found that depletion of PERK, PI3K p110α and LRP1 but not caspase-8 reduced the immunogenicity of the cancer cells. These results unravel a novel PERK-dependent subroutine for the early and simultaneous emission of two critical DAMPs following ROS-mediated ER stress.
authors.affiliation: Cell Death Research and Therapy Unit, Department of Cellular and Molecular Medicine KU Leuven, KU Leuven, Leuven, Belgium.
authors.forename: Abhishek D
authors.initials: AD
authors.lastname: Garg
authors.forename: Dmitri V
authors.initials: DV
authors.lastname: Krysko
authors.forename: Tom
authors.initials: T
authors.lastname: Verfaillie
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Kaczmarek
authors.forename: Gabriela B
authors.initials: GB
authors.lastname: Ferreira
authors.forename: Thierry
authors.initials: T
authors.lastname: Marysael
authors.forename: Noemi
authors.initials: N
authors.lastname: Rubio
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Firczuk
authors.forename: Chantal
authors.initials: C
authors.lastname: Mathieu
authors.forename: Anton J M
authors.initials: AJ
authors.lastname: Roebroek
authors.forename: Wim
authors.initials: W
authors.lastname: Annaert
authors.forename: Jakub
authors.initials: J
authors.lastname: Golab
authors.forename: Peter
authors.initials: P
authors.lastname: de Witte
authors.forename: Peter
authors.initials: P
authors.lastname: Vandenabeele
authors.forename: Patrizia
authors.initials: P
authors.lastname: Agostinis
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D015703:Antigens, CD / Q000378:metabolism; D018122:B7-1 Antigen / Q000378:metabolism; D051940:B7-2 Antigen / Q000378:metabolism; D037282:Calreticulin / Q000378:metabolism*; D016923:Cell Death; D002460:Cell Line; D003713:Dendritic Cells / Q000276:immunology; D004721:Endoplasmic Reticulum / Q000187:drug effects; D000949:Histocompatibility Antigens Class II / Q000378:metabolism; D006801:Humans; D007136:Immunoglobulins / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism; D009369:Neoplasms / Q000276:immunology*; D017319:Photosensitizing Agents / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism / Q000633:toxicity; D000097802:CD83 Antigen
chemical_list: D000255:Adenosine Triphosphate; D015703:Antigens, CD; D018122:B7-1 Antigen; D051940:B7-2 Antigen; D037282:Calreticulin; D000949:Histocompatibility Antigens Class II; D007136:Immunoglobulins; D008562:Membrane Glycoproteins; D017319:Photosensitizing Agents; D017382:Reactive Oxygen Species; D000097802:CD83 Antigen; C497964:CD86 protein, human