Title: Telomere elongation in immortal human cells without detectable telomerase activity.
Abstract: Research Article1 September 1995free access Telomere elongation in immortal human cells without detectable telomerase activity. T. M. Bryan T. M. Bryan Cancer Research Group, Children's Medical Research Institute, Westmead, Sydney, NSW, Australia. Search for more papers by this author A. Englezou A. Englezou Cancer Research Group, Children's Medical Research Institute, Westmead, Sydney, NSW, Australia. Search for more papers by this author J. Gupta J. Gupta Cancer Research Group, Children's Medical Research Institute, Westmead, Sydney, NSW, Australia. Search for more papers by this author S. Bacchetti S. Bacchetti Cancer Research Group, Children's Medical Research Institute, Westmead, Sydney, NSW, Australia. Search for more papers by this author R. R. Reddel R. R. Reddel Cancer Research Group, Children's Medical Research Institute, Westmead, Sydney, NSW, Australia. Search for more papers by this author T. M. Bryan T. M. Bryan Cancer Research Group, Children's Medical Research Institute, Westmead, Sydney, NSW, Australia. Search for more papers by this author A. Englezou A. Englezou Cancer Research Group, Children's Medical Research Institute, Westmead, Sydney, NSW, Australia. Search for more papers by this author J. Gupta J. Gupta Cancer Research Group, Children's Medical Research Institute, Westmead, Sydney, NSW, Australia. Search for more papers by this author S. Bacchetti S. Bacchetti Cancer Research Group, Children's Medical Research Institute, Westmead, Sydney, NSW, Australia. Search for more papers by this author R. R. Reddel R. R. Reddel Cancer Research Group, Children's Medical Research Institute, Westmead, Sydney, NSW, Australia. Search for more papers by this author Author Information T. M. Bryan1, A. Englezou1, J. Gupta1, S. Bacchetti1 and R. R. Reddel1 1Cancer Research Group, Children's Medical Research Institute, Westmead, Sydney, NSW, Australia. The EMBO Journal (1995)14:4240-4248https://doi.org/10.1002/j.1460-2075.1995.tb00098.x PDFDownload PDF of article text and main figures. ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InMendeleyWechatReddit Figures & Info Immortalization of human cells is often associated with reactivation of telomerase, a ribonucleoprotein enzyme that adds TTAGGG repeats onto telomeres and compensates for their shortening. We examined whether telomerase activation is necessary for immortalization. All normal human fibroblasts tested were negative for telomerase activity. Thirteen out of 13 DNA tumor virus-transformed cell cultures were also negative in the pre-crisis (i.e. non-immortalized) stage. Of 35 immortalized cell lines, 20 had telomerase activity as expected, but 15 had no detectable telomerase. The 15 telomerase-negative immortalized cell lines all had very long and heterogeneous telomeres of up to 50 kb. Hybrids between telomerase-negative and telomerase-positive cells senesced. Two senescent hybrids demonstrated telomerase activity, indicating that activation of telomerase is not sufficient for immortalization. Some hybrid clones subsequently recommenced proliferation and became immortalized either with or without telomerase activity. Those without telomerase activity also had very long and heterogeneous telomeres. Taken together, these data suggest that the presence of lengthened or stabilized telomeres is necessary for immortalization, and that this may be achieved either by the reactivation of telomerase or by a novel and as yet unidentified mechanism. Previous ArticleNext Article Volume 14Issue 171 September 1995In this issue RelatedDetailsLoading ...