title: Butylidenephthalide suppresses human telomerase reverse transcriptase (TERT) in human glioblastomas.
abstract: BACKGROUND
  Telomerase is widely expressed in most human cancers, but is almost undetectable in normal somatic cells and is therefore a potential drug target. Using the human telomerase promoter platform, the naturally occurring compound butylidenephthalide (BP) was selected for subsequent investigation of antitumor activity in vitro and in vivo.
  
  
  METHODS
  We treated human glioblastoma cells with BP and found a dose-dependent decrease in human telomerase reverse transcriptase (hTERT) mRNA expression and a concomitant increase in p16 and p21 expression. Because c-Myc and Sp1 are involved in transcriptional regulation of hTERT, the effect of BP on c-Myc and Sp1 expression was examined.
  
  
  RESULTS
  Using electrophoretic mobility shift assays and western blotting, we showed that BP represses hTERT transcriptional activity via downregulation of Sp1 expression. Using the telomerase repeat amplification protocol, an association between BP concentration and suppression of telomerase activity, induction of human glioblastoma senescence, and inhibition of cellular proliferation was identified. This was supported by a mouse xenograft model, in which BP repressed telomerase and inhibited tumor proliferation, resulting in tumor senescence. Overexpression of hTERT restored telomerase activity in human glioblastoma cells and overcame replicative senescence.
  
  
  CONCLUSIONS
  These findings suggest that BP inhibits proliferation and induces senescence in human glioblastomas by downregulating hTERT expression and consequently telomerase activity. This is the first study to describe regulation of telomerase activity by BP in human glioblastomas.
authors.affiliation: Department of Life Science and Graduate Institute of Biotechnology, National Dong Hwa University, Hualien, Taiwan, Republic of China.
authors.forename: Po-Cheng
authors.initials: PC
authors.lastname: Lin
authors.forename: Shinn-Zong
authors.initials: SZ
authors.lastname: Lin
authors.forename: Yi-Lin
authors.initials: YL
authors.lastname: Chen
authors.forename: Jeng-Shou
authors.initials: JS
authors.lastname: Chang
authors.forename: Li-Ing
authors.initials: LI
authors.lastname: Ho
authors.forename: Po-Yen
authors.initials: PY
authors.lastname: Liu
authors.forename: Li-Fu
authors.initials: LF
authors.lastname: Chang
authors.forename: Yeu-Chern
authors.initials: YC
authors.lastname: Harn
authors.forename: Shee-Ping
authors.initials: SP
authors.lastname: Chen
authors.forename: Li-Yi
authors.initials: LY
authors.lastname: Sun
authors.forename: Pi-Chun
authors.initials: PC
authors.lastname: Huang
authors.forename: Jung-Ting
authors.initials: JT
authors.lastname: Chein
authors.forename: Chang-Hai
authors.initials: CH
authors.lastname: Tsai
authors.forename: Chii-Wen
authors.initials: CW
authors.lastname: Chou
authors.forename: Horng-Jyh
authors.initials: HJ
authors.lastname: Harn
authors.forename: Tzyy-Wen
authors.initials: TW
authors.lastname: Chiou
mesh_terms: D000818:Animals; D015153:Blotting, Western; D001932:Brain Neoplasms / Q000188:drug therapy / Q000201:enzymology* / Q000473:pathology; D049109:Cell Proliferation / Q000187:drug effects*; D016922:Cellular Senescence / Q000187:drug effects; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic; D019942:Genes, p16; D005909:Glioblastoma / Q000188:drug therapy / Q000201:enzymology* / Q000473:pathology; D006801:Humans; D007124:Immunoenzyme Techniques; D051379:Mice; D008819:Mice, Nude; D010796:Phthalic Anhydrides / Q000494:pharmacology*; D011401:Promoter Regions, Genetic / Q000235:genetics; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019098:Telomerase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
chemical_list: C493957:Cdkn1a protein, mouse; D050759:Cyclin-Dependent Kinase Inhibitor p21; D010796:Phthalic Anhydrides; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger; C509186:TERT protein, human; D019098:Telomerase; C026105:butylidenephthalide