title: Interferon-γ induces senescence in normal human melanocytes.
abstract: BACKGROUND
  Interferon-γ (IFN-γ) plays an important role in the proceedings of vitiligo through recruiting lymphocytes to the lesional skin. However, the potential effects of IFN-γ on skin melanocytes and the subsequent contribution to the vitiligo pathogenesis are still unclear.
  
  
  OBJECTIVE
  To investigate the effects of IFN-γ on viability and cellular functions of melanocytes.
  
  
  METHODS
  Primary human melanocytes were treated with IFN-γ. Cell viability, apoptosis, cell cycle melanin content and intracellular reactive oxygen species (ROS) level were measured. mRNA expression was examined by real-time PCR. The release of interleukin 6 (IL-6) and heat shock protein 70 (HSP-70) was monitored by ELISA. β-galactosidase staining was utilized to evaluate melanocyte senescence.
  
  
  RESULTS
  Persistent IFN-γ treatment induced viability loss, apoptosis, cell cycle arrest and senescence in melanocytes. Melanocyte senescence was characterized as the changes in pigmentation and morphology, as well as the increase of β-galactosidase activity. Increase of p21Cip1/Waf1 protein was evident in melanocytes after IFN-γ treatment. IFN-γ induction of senescence was attenuated by siRNAs against p21, Janus kinase 2 (JAK2) or signal transducer and activator of transcription 1 (STAT1), but not by JAK1 siRNA nor by p53 inhibitor pifithrin-α. IFN-γ treatment increased the accumulation of intracellular ROS in melanocytes, while ROS scavenger N-acetyl cysteine (NAC) effectively inhibited IFN-γ induced p21 expression and melanocyte senescence. IL-6 and HSP-70 release was significantly induced by IFN-γ treatment, which was largely inhibited by NAC. The increase of IL-6 and HSP-70 release could also be observed in senescent melanocytes.
  
  
  CONCLUSIONS
  IFN-γ can induce senescence in melanocytes and consequently enhance their immuno-competency, leading to a vitiligo-prone milieu.
authors.affiliation: Department of Dermatology, Hangzhou Institute of Dermatology and Venereology, Third People's Hospital of Hangzhou, Hangzhou, Zhejiang Province, China.
authors.forename: Suiquan
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Dermatology, Hangzhou Institute of Dermatology and Venereology, Third People's Hospital of Hangzhou, Hangzhou, Zhejiang Province, China.
authors.forename: Miaoni
authors.initials: M
authors.lastname: Zhou
authors.affiliation: Department of Dermatology, Hangzhou Institute of Dermatology and Venereology, Third People's Hospital of Hangzhou, Hangzhou, Zhejiang Province, China.
authors.forename: Fuquan
authors.initials: F
authors.lastname: Lin
authors.affiliation: Department of Dermatology, Hangzhou Institute of Dermatology and Venereology, Third People's Hospital of Hangzhou, Hangzhou, Zhejiang Province, China.
authors.forename: Dongyin
authors.initials: D
authors.lastname: Liu
authors.affiliation: Department of Dermatology, Hangzhou Institute of Dermatology and Venereology, Third People's Hospital of Hangzhou, Hangzhou, Zhejiang Province, China.
authors.forename: Weisong
authors.initials: W
authors.lastname: Hong
authors.affiliation: Department of Dermatology, Hangzhou Institute of Dermatology and Venereology, Third People's Hospital of Hangzhou, Hangzhou, Zhejiang Province, China; Zhejiang Chinese Medical University, Hangzhou, Zhejiang Province, China.
authors.forename: Liangjun
authors.initials: L
authors.lastname: Lu
authors.affiliation: Department of Dermatology, Hangzhou Institute of Dermatology and Venereology, Third People's Hospital of Hangzhou, Hangzhou, Zhejiang Province, China; Zhejiang Chinese Medical University, Hangzhou, Zhejiang Province, China.
authors.forename: Yiping
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Department of Dermatology, Hangzhou Institute of Dermatology and Venereology, Third People's Hospital of Hangzhou, Hangzhou, Zhejiang Province, China.
authors.forename: Aie
authors.initials: A
authors.lastname: Xu
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000375:Aging / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology*; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D002453:Cell Cycle / Q000187:drug effects; D059447:Cell Cycle Checkpoints / Q000187:drug effects; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000187:drug effects / Q000502:physiology*; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism*; D015850:Interleukin-6 / Q000378:metabolism; D033862:Iron-Binding Proteins / Q000378:metabolism; D053613:Janus Kinase 1 / Q000378:metabolism; D053614:Janus Kinase 2 / Q000378:metabolism; D008544:Melanocytes / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology*; D010766:Phosphorylation / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D050794:STAT1 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D019941:Cyclin-Dependent Kinase Inhibitor p16; D050759:Cyclin-Dependent Kinase Inhibitor p21; D015850:Interleukin-6; D033862:Iron-Binding Proteins; D017382:Reactive Oxygen Species; D050794:STAT1 Transcription Factor; D016159:Tumor Suppressor Protein p53; C008166:iron-binding seminal plasma antigen; D007371:Interferon-gamma; C507924:JAK2 protein, human; D053613:Janus Kinase 1; D053614:Janus Kinase 2; D001616:beta-Galactosidase; D000111:Acetylcysteine