Telomerase inhibitors and Activators : Pharmaceutical Importance

Telomeres are specialized functional complexes that protect the ends of eukaryotic chromosomes. The telomeric DNA sequences are tandem repeats of a short hexameric sequence unit. The inability to DNA polymerase to replicate the end of the chromosome during lagging strand synthesis results in the loss of telomeric repeats when cell divides. Telomere shortening provides a barrier to cancer progression and the majority of the cancer cells depend on the activation of telomerase to gain proliferative immortality. Thus, telomerase is a molecular target for diseases since its discovery. Telomerase inhibition enables more specific ground for cancer therapy because the telomerase is not detected in most normal tissues. Some of the synthetic and natural telomerase inhibitors were tried on various cancer cells and there was a decrease in the number of cancer cells. But on the other hand, telomere shortening correlates with cellular aging. Some evidence suggests that the progressive loss of telomeric repeats of chromosomes may function as a molecular clock that triggers senescence. Telomerase-related gene mutations also result in some diseases. Because of this, telomerase activators are important for antiaging and telomerase-dependent disease treatments. This chapter summarizes the pharmaceutical importance of telomeres, telomerase structure, telomerase activators, and inhibitors.