title: Inhibition of telomerase activity by dominant-negative hTERT retards the growth of breast cancer cells.
abstract: BACKGROUND
  Telomerase, a ribonucleoprotein enzyme mainly consisted of a catalytic protein subunit human telomerase reverse transcriptase (hTERT) and a human telomerase RNA component, is responsible for maintaining telomeres. Telomerase over-expression correlates significantly with tumors and is a prognostic marker. However, telomerase over-expression in breast cancers and the effect of telomerase inhibition as a candidate cancer therapy are unknown.
  
  
  METHODS
  We used the dominant-negative mutant of hTERT (DN-hTERT) to inhibit telomerase activity on human breast adenocarcinoma cell line MCF-7 by transfection. Telomeric repeat amplification protocol assays and real-time quantitative RT-PCR were performed to investigate telomerase activity as well as expression of hTERT. Telomere length was measured by the flow-fluorescence in situ hybridization assay. Cell proliferation was assessed by the WST-8 assay, and apoptosis was evaluated by flow cytometry. The tumor formation ability of MCF-7 cells was investigated by transplanting cells subcutaneously into BALB/c nude mice.
  
  
  RESULTS
  Ectopic expression of DN-hTERT caused dramatically inhibition of telomerase activity and reduction of telomere length. Telomerase inhibition induced growth arrest and apoptosis of MCF7 cells in vitro and loss of tumorigenic properties in vivo.
  
  
  CONCLUSIONS
  This study shows that telomerase inhibition by DN-hTERT can effectively inhibit the cell viability and tumorigenicity of MCF7 cells and is an attractive approach for breast cancer therapy.
authors.affiliation: Luoyang Orthopedic Hospital of Henan Province, Luoyang, 471000, Henan, China. yaojianr@126.com.
authors.forename: Yaojian
authors.initials: Y
authors.lastname: Rao
authors.affiliation: The orthopedic department of tongji hospital affiliated to Tongji Medical College of Huazhong University of Science and Technology, Wuhan, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Xiong
authors.affiliation: Luoyang Orthopedic Hospital of Henan Province, Luoyang, 471000, Henan, China.
authors.forename: Huijuan
authors.initials: H
authors.lastname: Liu
authors.affiliation: Luoyang Orthopedic Hospital of Henan Province, Luoyang, 471000, Henan, China.
authors.forename: Chunxia
authors.initials: C
authors.lastname: Jia
authors.affiliation: Luoyang Orthopedic Hospital of Henan Province, Luoyang, 471000, Henan, China.
authors.forename: Hongxing
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Luoyang Orthopedic Hospital of Henan Province, Luoyang, 471000, Henan, China.
authors.forename: Zesheng
authors.initials: Z
authors.lastname: Cui
authors.affiliation: Luoyang Orthopedic Hospital of Henan Province, Luoyang, 471000, Henan, China.
authors.forename: Ya
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Luoyang Orthopedic Hospital of Henan Province, Luoyang, 471000, Henan, China.
authors.forename: Jiawei
authors.initials: J
authors.lastname: Cui
mesh_terms: D000818:Animals; D017209:Apoptosis; D001943:Breast Neoplasms / Q000201:enzymology / Q000473:pathology / Q000517:prevention & control*; D049109:Cell Proliferation; D005260:Female; D005434:Flow Cytometry; D005799:Genes, Dominant; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019098:Telomerase / Q000037:antagonists & inhibitors* / Q000235:genetics; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays
chemical_list: D012333:RNA, Messenger; C509186:TERT protein, human; D019098:Telomerase
keywords: Breast cancer; DN-hTERT; MCF-7; Telomerase activity