title: Human telomerase catalytic subunit gene re-expression is an early event in oral carcinogenesis.
abstract: OBJECTIVE
  Detection of telomerase catalytic subunit (hTERT) mRNA has been used as a surrogate marker for estimation of telomerase activity. The exact role and timing of telomerase re-activation, a key enzyme implicated in cellular immortalization and transformation, in the multistep process of oral carcinogenesis is still unknown. The aim was to test the hypothesis that (i) quantitative rather than qualitative differences exist in the level of hTERT mRNA expression between normal oral mucosa, different grades of oral epithelial abnormalities and squamous cell carcinomas of the oral cavity, and that (ii) hTERT gene re-expression is an important, probably early event in oral carcinogenesis.
  
  
  RESULTS
  The relative quantity of hTERT mRNA was analysed in 45 frozen oral epithelia representing different morphological stages of oral carcinogenesis classified according to the Ljubljana classification and in 37 oral squamous cell carcinomas, using a commercially available LightCycler Telo TAGGG hTERT Quantification kit. hTERT mRNA was not detected in normal or reactive hyperplastic oral epithelia, but was present in 43% of atypical hyperplasias (premalignant lesions), 60% of intraepithelial carcinomas and 68% of oral squamous cell carcinomas. Statistical analysis revealed two groups of oral epithelial changes, with significant differences in the levels of hTERT mRNA expression: 1, normal and reactive hyperplastic oral epithelium, and 2, atypical hyperplasia, intraepithelial carcinomas and squamous cell carcinomas.
  
  
  CONCLUSIONS
  These data suggest that hTERT gene re-expression represents an early event in the multistep process of oral carcinogenesis, already detectable at the stage of precancerous oral epithelial changes. Nevertheless, other genetic aberrations appear to be necessary for progression of oral epithelial abnormalities towards invasive squamous cell carcinoma.
authors.affiliation: Institute of Microbiology & Immunology, University of Ljubljana, Slovenia. bostjan.luzar@mf.uni-lj.si
authors.forename: B
authors.initials: B
authors.lastname: Luzar
authors.forename: M
authors.initials: M
authors.lastname: Poljak
authors.forename: I J
authors.initials: IJ
authors.lastname: Marin
authors.forename: A
authors.initials: A
authors.lastname: Eberlinc
authors.forename: U
authors.initials: U
authors.lastname: Klopcic
authors.forename: N
authors.initials: N
authors.lastname: Gale
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000473:pathology; D020134:Catalytic Domain / Q000235:genetics*; D004268:DNA-Binding Proteins; D004848:Epithelium / Q000378:metabolism / Q000473:pathology; D015870:Gene Expression; D006801:Humans; D006965:Hyperplasia; D009062:Mouth Neoplasms / Q000235:genetics / Q000473:pathology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019098:Telomerase / Q000235:genetics*; D013997:Time Factors
chemical_list: D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D019098:Telomerase