Telomerase: A link between cancer and biological immortality

Cancer is a leading cause of death worldwide, with approximately 18.1 million new cases and 9.6 million fatalities annually. Many studies have shown that telomeres and telomerase play crucial roles in the progression of almost all types of cancer. The length of telomeres is reduced with each cell division, and when they become too short, the cells can no longer divide and die. Telomerase is responsible for maintaining the length of the telomere during replication. In healthy cells, telomerase is only active during embryonic development and gamete formation. Telomerase is inactive in most somatic cells and highly active in germ cells, stem cells, and cancer cells. This activity ensures that somatic cells can only divide a finite number of times (Hayflick limit) before they reach senescence and enter apoptosis. However, cancer cells express high levels of telomerase and can divide indefinitely. This makes them immortal, eating away from the host’s resources, and acquiring properties, such as loss of cell adhesion, metastasis, and loss of contact inhibition, which creates tissue lumps wherever the tumor develops. Many recent advances in science and technology have shown the significant role of telomerase in cancer and aging, which also opens a wide door for cancer treatment, hoping for patients back to life. In this review, we discuss the significance of telomerase and its effect on cancer progression and various research and therapeutic aspects of telomerase.