title: Telomerase activity in HeLa cervical carcinoma cell line proliferation.
abstract: Normal human somatic cells in culture have a limited dividing potential. This is due to DNA end replication problem, whereby telomeres shorten with each subsequent cell division. When a critical telomere length is reached cells enter senescence. To overcome this problem, immortal HeLa cell line express telomerase, an enzyme that prevents telomere shortening. Although immortal, the existence of non-dividing cells that do not incorporate (3)H-thymidine over 24 h of growth has been well documented in this cell line. Using DiI labeling and high-speed cell sorting, we have separated and analyzed fractions of HeLa cells that divided vigorously as well as those that cease divisions over several days in culture. We also analyzed telomerase activity in separated fractions and surprisingly, found that the fraction of cells that divided 0-1 time over 6 days in culture have several times higher endogenous telomerase activity than the fastest dividing fraction. Additionally, the non-growing fraction regains an overall high labeling index and low SA-beta-Gal activity when subcultured again. This phenomenon should be considered if telomerase inhibition is to be used as an approach to cancer therapy. In this paper we also discuss possible molecular mechanisms that underlie the observed results.
authors.affiliation: Department of Molecular Biology, Ruder Bosković Institute, Bijenicka 54, 10000 Zagreb, Croatia.
authors.forename: Milena
authors.initials: M
authors.lastname: Ivanković
authors.forename: Andrea
authors.initials: A
authors.lastname: Cukusić
authors.forename: Ivana
authors.initials: I
authors.lastname: Gotić
authors.forename: Nikolina
authors.initials: N
authors.lastname: Skrobot
authors.forename: Mario
authors.initials: M
authors.lastname: Matijasić
authors.forename: Denis
authors.initials: D
authors.lastname: Polancec
authors.forename: Ivica
authors.initials: I
authors.lastname: Rubelj
mesh_terms: D002232:Carbocyanines; D049109:Cell Proliferation; D002469:Cell Separation / Q000379:methods; D016922:Cellular Senescence; D005260:Female; D005434:Flow Cytometry; D005456:Fluorescent Dyes; D006367:HeLa Cells; D006801:Humans; D010641:Phenotype; D019098:Telomerase / Q000378:metabolism*; D013997:Time Factors; D014316:Tritium; D002583:Uterine Cervical Neoplasms / Q000201:enzymology* / Q000473:pathology; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D002232:Carbocyanines; D005456:Fluorescent Dyes; D014316:Tritium; C024286:3,3'-dioctadecylindocarbocyanine; D019098:Telomerase; D001616:beta-Galactosidase