Assembly of mutant-template telomerase RNA into catalytically active telomerase ribonucleoprotein that can act on telomeres is required for apoptosis and cell cycle arrest in human cancer cells.
The telomerase ribonucleoprotein is a promising target for cancer therapy, as it is highly active in many human malignancies. A novel telomerase targeting approach combines short interfering RNA (siRNA) knockdown of endogenous human telomerase RNA (hTer) with expression of a mutant-template hTer (MT-hTer). Such combination MT-hTer/siRNA constructs induce a rapid DNA damage response, telomere uncapping, and inhibition of cell proliferation in a variety of human cancer cell lines. We tested which functional aspects of the protein catalytic component of telomerase [human telomerase reverse transcriptase (hTERT)] are required for these effects using human LOX melanoma cells overexpressing various hTERTs of known properties. Within 3 days of MT-hTer/siRNA introduction, both growth inhibition and DNA damage responses were significantly higher in the setting of wild-type hTERT versus catalytically dead hTERT or mutant hTERT that is catalytically competent but unable to act on telomeres. These effects were not attenuated by siRNA-induced knockdown of the telomeric protein human Rap1 and were additive with knockdown of the telomere-binding protein TRF2. Hence, the effects of MT-hTer/siRNA require a telomerase that is both catalytically competent to polymerize DNA and able to act on telomeres in cells.
Goldkorn
Amir
A
Department of Internal Medicine, Division of Hematology and Oncology, University of California at San Francisco, San Francisco, California, USA.
Blackburn
Elizabeth H
EH
D000483:Alleles; D017209:Apoptosis / Q000502:physiology; D002384:Catalysis; D002453:Cell Cycle / Q000502:physiology; D048708:Cell Growth Processes / Q000502:physiology; D045744:Cell Line, Tumor; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D008545:Melanoma / Q000201:enzymology / Q000235:genetics / Q000378:metabolism* / Q000628:therapy; D009154:Mutation; D012313:RNA / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D012190:Retroviridae / Q000235:genetics; D019098:Telomerase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D016615:Telomere / Q000235:genetics / Q000378:metabolism*
D004268:DNA-Binding Proteins; D034741:RNA, Small Interfering; C422952:telomerase RNA; D012313:RNA; D019098:Telomerase