Ectopic expression of a COOH-terminal fragment of the human telomerase reverse transcriptase leads to telomere dysfunction and reduction of growth and tumorigenicity in HeLa cells.
The COOH-terminus of telomerase reverse transcriptase (hTERT) has been shown to participatein the nuclear translocation of TERT. Here, we constructed plasmids expressing the COOH-terminal M(r) 27,000 polypeptide of hTERT (hTERTC27) withthe telomerase RNA-binding domains and the reverse transcriptase domains deleted. We showed that ectopic overexpression of this polypeptide caused a defect in telomere maintenance in hTERT-positive HeLa cells, which led to senescence-like growth arrest and apoptosis. The hTERTC27 appears to work by inducing telomere dysfunction, exemplified by significantly increased anaphase chromosome end-to-end fusion events in transfected cells. Significantly, it had no effect on the cellular telomerase enzymatic activity or telomere length. The in vivo effect was further demonstrated as HeLa cells stably expressing hTERTC27 have significantly lower growth rate and reduced tumorigenicity in nude mice xenografts. Results from this study revealed an important function for the COOH terminus of hTERT in maintaining the integrity of telomere structure and chromosome ends, as well as in cell senescence and apoptosis. Furthermore, hTERTC27 provides a new strategy for cancer therapy by inducing telomere dysfunction in cancer cells without affecting the telomerase enzymatic activity.
Huang
Jun Jian
JJ
Department Molecular Genetics, Beijing Institute of Biotechnology, Beijing, China.
Lin
Marie C
MC
Bai
Yun Xiu
YX
Jing
Da Dao
DD
Wong
Benjamin C Y
BC
Han
Su Wen
SW
Lin
Jian
J
Xu
Bing
B
Huang
Cui-Fen
CF
Kung
Hsiang-Fu
HF
D000818:Animals; D017209:Apoptosis / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D004268:DNA-Binding Proteins; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D010446:Peptide Fragments / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D019098:Telomerase / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D016615:Telomere / Q000502:physiology*; D014162:Transfection; D023041:Xenograft Model Antitumor Assays
D004268:DNA-Binding Proteins; D010446:Peptide Fragments; C509186:TERT protein, human; D019098:Telomerase; C509187:Tert protein, mouse