Article

Multiple pathways for the regulation of telomerase activity.

Department of Cell Biology and Neuroscience, University of Texas Southwestern Medical Center, Dallas 75235-9039, USA.
European Journal of Cancer (impact factor: 5.54). 05/1997; 33(5):761-6. DOI:10.1016/S0959-8049(97)00066-X pp.761-6
Source: PubMed

ABSTRACT The ends of vertebrate chromosome are composed of large tracts of a repeated sequence, TTAGGG, which are known as telomeres. Normal somatic cells progressively lose telomeric repeats with each successive cell division due to incomplete replication. Immortal and cancer cells compensate for telomeric loss by expressing the enzyme telomerase, an RNA-dependent DNA polymerase that maintains telomere length. Telomerase activity has been detected in almost 90% of all human cancers. Telomerase activity is generally absent in normal somatic tissues but is detected in adult testes, activated lymphocytes, and lower levels are expressed in proliferative cells of renewal tissues. Telomerase activity is downregulated in cells that exit the cell cycle via either terminal differentiation or (reversible) quiescence. Inhibition of telomerase activity in tumour cells may provide an effective way to treat cancer by potentially reducing the recurrence of tumours due to occult micro-metastases. An understanding of the pathways involved in telomerase regulation will be important for determining the most practical means of inhibiting its activity.

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Keywords

adult testes
 
cancer cells
 
cell cycle
 
enzyme telomerase
 
human cancers
 
incomplete replication
 
Normal somatic cells
 
normal somatic tissues
 
occult micro-metastases
 
proliferative cells
 
renewal tissues
 
RNA-dependent DNA polymerase
 
successive cell division
 
telomerase activity
 
telomerase regulation
 
telomeric loss
 
terminal differentiation
 
tumour cells
 
tumours
 
vertebrate chromosome
 

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