Methods and compositions for modulation and inhibition of telomerase

It was found that normal human stem cells produce a regulated non-processive telomerase activity, while cancer cells produce a processive telomerase activity. Nucleotide analogs, such as 7-deaza-2'-deoxyquanosine-5'-triphosphate (7-deaza-dGTP) were found to be substrates for processive telomerase and incorporated into telomeric sequence. The incorporation of this nucleotide subsequently affected the processivity of telomerase, converting processive telomerase to non-processive telomerase. The incorporation of this nucleotide analogs was also found to inhibit formation of G-quartets by telomeric sequence. Other methods for converting cancer processive telomerase to the more benign non-processive telomerase include partially cleaving the telomerase RNA. The nucleoside analogs were found to be capable of a variety of activities including mediating allosteric-like inhibition of telomerase, premature termination and shortening of telomeric DNA, destabilization of telomeric structure and function and eventually cell death. Understanding the mechanisms of telomerase modulation by the 7-deaza-nucleotides has allowed the design of new telomerase inhibitors, modulators and agents for affecting telomere structure and function. These discoveries have application in the treatment of cancer.