title: Nanoparticle-induced photocatalytic head and neck squamous cell carcinoma cell death is associated with autophagy.
abstract: OBJECTIVE
  To characterize molecular mechanisms underlying photocatalytic cell death of head and neck squamous cell carcinoma (HNSCC) by zinc oxide nanoparticles (ZnO-NPs).
  
  
  METHODS
  Human HNSCC-derived FaDu cells were incubated with ZnO-NPs followed by UVA-1 irradiation. Cytotoxicity was assessed by MTT assay and annexin-V propidium iodide test. Autophagy was detected by autophagosome accumulation, conversion of light chain 3 I to II, and lysosomal activity. The generation of reactive oxygen species was measured using the 2',7'-dichlorofluorescein-diacetate test.
  
  
  RESULTS
  Apoptosis-independent cytotoxic effects were induced by 0.2- and 2-µg/ml ZnO-NPs and UVA-1. FaDu cells promoted autophagosome formation. Significantly elevated light chain 3 II and reactive oxygen species were seen after the combined application of both ZnO-NPs and UVA-1 as photocatalytic treatment. Autophagy probably mediates cell survival under UVA-1 or ZnO-NP exposure alone but induces self-digestive cell death after combined treatment.
  
  
  CONCLUSIONS
  The effect of autophagy on HNSCC viability after nanoparticle-induced photocatalytic treatment seems to depend on the impact of the physicochemical trigger.
authors.affiliation: Department of Oto-Rhino-Laryngology, Plastic, Aesthetic & Reconstructive Head & Neck Surgery, University Hospital of Wuerzburg, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Hackenberg
authors.forename: Agmal
authors.initials: A
authors.lastname: Scherzed
authors.forename: Antje
authors.initials: A
authors.lastname: Gohla
authors.forename: Antje
authors.initials: A
authors.lastname: Technau
authors.forename: Katrin
authors.initials: K
authors.lastname: Froelich
authors.forename: Christian
authors.initials: C
authors.lastname: Ginzkey
authors.forename: Christian
authors.initials: C
authors.lastname: Koehler
authors.forename: Marc
authors.initials: M
authors.lastname: Burghartz
authors.forename: Rudolf
authors.initials: R
authors.lastname: Hagen
authors.forename: Norbert
authors.initials: N
authors.lastname: Kleinsasser
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy / Q000187:drug effects*; D002294:Carcinoma, Squamous Cell / Q000139:chemically induced / Q000209:etiology / Q000235:genetics*; D002384:Catalysis; D045744:Cell Line, Tumor; D006258:Head and Neck Neoplasms / Q000139:chemically induced / Q000209:etiology / Q000235:genetics*; D006801:Humans; D053768:Metal Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D010777:Photochemistry; D017382:Reactive Oxygen Species / Q000378:metabolism; D000077195:Squamous Cell Carcinoma of Head and Neck; D015034:Zinc Oxide / Q000494:pharmacology / Q000633:toxicity*
chemical_list: D017382:Reactive Oxygen Species; D015034:Zinc Oxide