title: Wogonin induced apoptosis in human nasopharyngeal carcinoma cells by targeting GSK-3β and ΔNp63.
abstract: OBJECTIVE
  Wogonin, a plant flavonoid, has antitumor activity in various cancers. Dysregulation of GSK-3β has been implicated in tumorigenesis and cancer progression. In this study, we investigated the antitumor activity and the mechanistic action of wogonin in human nasopharyngeal carcinoma (NPC) cells.
  
  
  METHODS
  The effects of wogonin on the cell survival and apoptosis in NPC cells were investigated by MTS assay, flow cytometry, and PARP cleavage assays. Pharmacological inhibitors (BIO, LiCl, and OA), or small interfering RNA (siRNA) were used to address the expression status of GSK-3β and the anticancer effect of ΔNp63 in NPC cells.
  
  
  RESULTS
  Wogonin was shown to induce dose-dependent cell apoptosis due to the induction of sub-G1-phase cells, PARP cleavage, and downregulation of ΔNp63, a survival factor in NPC cells. Strikingly, the apoptotic effect of wogonin involved GSK-3β inactivation via prominent inhibition of phosphorylation at Tyr216 and slightly increment of phosphorylation at Ser9, while there is no change in total GSK-3β proteins. Dysregulation of GSK-3β caused cell apoptosis was confirmed by pharmacological inhibitors (lithium chloroid, LiCl, and 6-bro-moindirubin-3-oxime, BIO). Administration of okadaic acid (OA, a protein phosphatase inhibitor) that significantly inactivated GSK-3β also induced ΔNp63 downregulation and apoptosis. Targeted silencing of ΔNp63 repressed the phosphorylation of GSK-3β at Tyr216 and sensitized NPC cells to wogonin-induced apoptosis. Furthermore, GSK-3β or PP2A inhibitors enhanced wogonin-induced apoptosis via activation of caspase 3/7.
  
  
  CONCLUSIONS
  These results indicate that GSK-3β, as well as ΔNp63, are novel targets for wogonin action and suggest that wogonin might provide a potential therapeutic option in NPC. Further in vitro and in vivo studies will help to clarify the therapeutic role of wogonin in NPC.
authors.affiliation: Center for General Studies, Chang Gung University, Taoyuan, Taiwan. chowse@mail.cgu.edu.tw
authors.forename: Shu-Er
authors.initials: SE
authors.lastname: Chow
authors.forename: Ying-Ling
authors.initials: YL
authors.lastname: Chang
authors.forename: Sun-Fa
authors.initials: SF
authors.lastname: Chuang
authors.forename: Jong-Shyan
authors.initials: JS
authors.lastname: Wang
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000008:administration & dosage / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D002277:Carcinoma; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D016503:Drug Delivery Systems; D044950:Flavanones / Q000008:administration & dosage / Q000494:pharmacology*; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D038362:Glycogen Synthase Kinase 3 / Q000235:genetics; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D014157:Transcription Factors / Q000235:genetics; D025521:Tumor Suppressor Proteins / Q000235:genetics
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D044950:Flavanones; C115051:TP63 protein, human; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D038362:Glycogen Synthase Kinase 3; C085514:wogonin