title: [Changes in telomerase activity decreases in MCF-7 cells during apoptosis induced by sodium butyrate].
abstract: OBJECTIVE
  To investigate telomerase activity of MCF-7 mammary cancer cells during apoptosis induced by sodium butyrate (SB) in vitro and its mechanism.
  
  
  METHODS
  The proliferative activity of MCF-7 cells was assessed by morphology and MTT assay. Cell apoptosis was confirmed by DNA fragmentation and phosphatidylserine (PS) externalization. Telomerase activity was examined by TRAP-ELISA. The expression status of telomerase subunits was analyzed by RT-PCR.
  
  
  RESULTS
  A time- and dose-dependent inhibition was detected in MCF-7 cells treated with SB. At 72 hr after SB (2.5 mmol/L) treatment, MCF-7 cells were apoptotic with a rate of 84.3% by flow cytometric assay (AnnexinV/PI double staining). Apoptosis was also confirmed by DNA fragmentation. Telomerase activity and expression level of hTERT, the key subunit of telomerase, decreased at 24-hour time point after SB treatment. No significant changes were observed in the expression of hTR and hTP, the other two subunits of telomerase.
  
  
  CONCLUSIONS
  Telomerase activity decreases in MCF-7 cells during apoptosis induced by sodium butyrate. The underlying mechanism might be related to the down regulation of hTERT transcription.
authors.affiliation: Department of Obstetrics and Gynecology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Xi
authors.forename: Ming-Fu
authors.initials: MF
authors.lastname: Wu
authors.forename: Jian-Hong
authors.initials: JH
authors.lastname: Wu
authors.forename: Fu-Jun
authors.initials: FJ
authors.lastname: Li
authors.forename: Yun-Ping
authors.initials: YP
authors.lastname: Lu
authors.forename: Jian-Feng
authors.initials: JF
authors.lastname: Zhou
authors.forename: Ding
authors.initials: D
authors.lastname: Ma
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D001943:Breast Neoplasms / Q000201:enzymology* / Q000473:pathology; D002087:Butyrates / Q000008:administration & dosage / Q000494:pharmacology*; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D006801:Humans; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D019098:Telomerase / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors
chemical_list: D002087:Butyrates; D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D019098:Telomerase