title: Inhibition of telomerase is related to the life span and tumorigenicity of human prostate cancer cells.
abstract: OBJECTIVE
  Telomerase, the enzyme that catalyzes the elongation of telomeres, is illegitimately activated in the majority of cancers, including that of the prostate, where it may greatly extend the life span of malignant cells. The inhibition of telomerase by molecular intervention has been shown to lead eventually to cell death in several tumor or in vitro immortalized cell lines and in 1 case prevent tumor growth in vivo. Therefore, we tested whether a similar strategy may be used to limit the tumorigenic potential of late stage prostate cancer cells.
  
  
  METHODS
  PC-3, LNCaP and DU-145 human prostate cancer cells were infected with a retrovirus encoding a dominant-negative version of the catalytic subunit of telomerase (DN-hTERT). Subclones or polyclonal populations were assayed for DN-hTERT expression, telomerase activity, telomere length, cell life span and in most cases tumorigenicity in nude mice.
  
  
  RESULTS
  DN-hTERT expression levels directly correlated with cell life span and tumorigenic growth. PC-3 cells expressing high levels of DN-hTERT died rapidly and failed to form tumors in nude mice, whereas cells expressing the lowest levels proliferated the longest and generated tumors that later spontaneously regressed. Similarly the inhibition of telomerase activity in LNCaP cells was greater than in DU-145 cells and correspondingly LNCaP cells had a shorter life span.
  
  
  CONCLUSIONS
  DN-hTERT expression limits the life span and tumorigenic potential of human prostate cancer cells, although the onset of these effects appears to be dictated by the expression level of DN-hTERT. Therefore, telomerase represents an attractive target for potentially managing prostate cancer. Nevertheless, effective means of inhibiting the enzyme may be required for a therapeutically useful outcome.
authors.affiliation: Department of Pharmacology, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: C
authors.initials: C
authors.lastname: Guo
authors.forename: D
authors.initials: D
authors.lastname: Geverd
authors.forename: R
authors.initials: R
authors.lastname: Liao
authors.forename: N
authors.initials: N
authors.lastname: Hamad
authors.forename: C M
authors.initials: CM
authors.lastname: Counter
authors.forename: D T
authors.initials: DT
authors.lastname: Price
mesh_terms: D000818:Animals; D016923:Cell Death; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D011471:Prostatic Neoplasms / Q000473:pathology*; D019098:Telomerase / Q000037:antagonists & inhibitors*; D014407:Tumor Cells, Cultured
chemical_list: D019098:Telomerase