title: Effect and mechanism of tacrolimus on melanogenesis on A375 human melanoma cells.
abstract: BACKGROUND
  Topical tacrolimus has been used for vitiligo as a common treatment option for more than ten years while the underlying mechanism is still uncertain. The aim of this study was to investigate the direct effects of tacrolimus on the melanogenesis and migration on human A375 melanoma cells. The expression of c-KIT mRNA and protein of human A375 cells were also investigated.
  
  
  METHODS
  The cultured A375 human melanoma cells were randomly assigned to control and tacrolimus treatment groups (10, 10(2), 10(3) and 10(4) nmol/L). The cell proliferation was measured with Cell Counting Kit-8 assays. Melanin content was measured with NaOH method. Transwell migration assay was used to measure cell migration. The expression of c-KIT mRNA and protein were measured with real-time fluorescence quantitative polymerase chain reaction and immunohistochemistry respectively.
  
  
  RESULTS
  The cell proliferation of the 10(3) and 10(4) nmol/L tacrolimus groups were significantly lower (0.666 ± 0.062 and 0.496 ± 0.038) as compared with the control (0.841 ± 0.110, P < 0.05). The mean melanin content in all groups treated with different concentration of tacrolimus (10, 10(2), 10(3), 10(4) nmol/L) increased compared with the control group (P < 0.05). Dose-dependent increase in cell migration were seen in all tacrolimus-treated groups (P < 0.01). The expression of c-KIT mRNA level in A375 cells exposed to tacrolimus (10(3) and 10(4) nmol/L) had significantly increased by 3.03-fold and 3.19-fold respectively compared with the control (P < 0.05).
  
  
  CONCLUSIONS
  Although tacrolimus had no effects on cell proliferation on A375 human melanoma cells, it could increase the melanin content and cell migration. The expression of c-KIT mRNA and protein increased dose-dependently in tacrolimus-treated groups as compared with the control. Our study demonstrated that tacrolimus could enhance the melanogenesis and cell migration on A375 cells.
authors.affiliation: Department of Dermatology, Peking University People's Hospital, Beijing 100044, China.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Huang
authors.affiliation: Department of Allergy, Beijing Shijitan Hospital, Beijing 100038, China.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Dermatology, Peking University People's Hospital, Beijing 100044, China.
authors.forename: Xiaolan
authors.initials: X
authors.lastname: Ding
authors.affiliation: Department of Dermatology, Peking University People's Hospital, Beijing 100044, China.
authors.forename: Qianxi
authors.initials: Q
authors.lastname: Xu
authors.affiliation: Department of Dermatology, Peking University People's Hospital, Beijing 100044, China.
authors.forename: Sonia Kay
authors.initials: SK
authors.lastname: Hwang
authors.affiliation: Department of Dermatology, Peking University People's Hospital, Beijing 100044, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Wang
authors.affiliation: Department of Dermatology, Peking University People's Hospital, Beijing 100044, China. Email: dujuan223@medmail.com.cn.
authors.forename: Juan
authors.initials: J
authors.lastname: Du
authors.affiliation: Department of Dermatology, Peking University People's Hospital, Beijing 100044, China.
authors.forename: Jianzhong
authors.initials: J
authors.lastname: Zhang
mesh_terms: D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects / Q000235:genetics; D049109:Cell Proliferation / Q000187:drug effects; D006801:Humans; D007150:Immunohistochemistry; D008543:Melanins / Q000378:metabolism; D008544:Melanocytes / Q000166:cytology* / Q000187:drug effects*; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D016559:Tacrolimus / Q000494:pharmacology*
chemical_list: D008543:Melanins; D012333:RNA, Messenger; D019009:Proto-Oncogene Proteins c-kit; D016559:Tacrolimus