Biology and Medicine

Importance of Telomeres and Telomerase from Protection to Proliferation in Cancer

Gabriel Campalans Department of Oncology, Paris-Saclay University, Paris, France

Received: 27-Jun-2023, Manuscript No. BLM-23-22820; Editor assigned: 30-Jun-2023, Pre QC No. BLM-23-22820(PQ); Reviewed: 14-Jul-2023, QC No. BLM-23-22820; Revised: 21-Jul-2023, Manuscript No. BLM-23-22820(R); Published: 28-Jul-2023, DOI: 10.35248/0974-8369.23.15.594

Description

Telomeres and telomerase hold a distinct significance in the field of Molecular Biology, where they have emerged as important elements in understanding the intricate connection between cellular immortality and regulated growth. Telomeres are the structures, residing at the ends of chromosomes, have profound implications for cancer development. Telomeres are repetitive DNA sequences (TTAGGG in humans) located at the ends of linear chromosomes. They serve as protective caps that shield the genetic material from degradation and fusion. However, with each cell division telomeres progressively shorten due to the "end replication problem," as the DNA polymerase cannot fully replicate the chromosome ends. This natural shortening process acts as a cellular clock, ultimately leading to cellular senescence or apoptosis, preventing un programmed cell division.

Telomerase is a specialized reverse transcriptase enzyme that replenishes telomere length by adding back the lost telomeric repeats, thereby maintaining the chromosomal integrity and ensures cell survival. Normally, telomerase activity is high during embryogenesis and decreases significantly in most somatic cells after birth. However, certain adult stem cells and germ cells retain telomerase activity, enabling them to divide and differentiate without the constraint of telomere shortening. The intriguing link between telomeres, telomerase, and cancer was unveiled through the phenomenon of immortalization. In many cancers, cells manage to bypass the normal limitations on cell division, leading to uncontrolled growth. This immortalization often involves the reactivation of telomerase, restoring telomere length and evading cellular senescence and apoptosis. Consequently, cancer cells can continue dividing indefinitely, a hallmark of malignancy.

Cancer cells exploit telomerase to increase their uncontrolled growth. The reactivation of telomerase, often achieved by upregulating the expression of its catalytic subunit, provides a selective advantage to cancer cells. Longer telomeres not only enable more divisions but also offer protection against DNA damage and chromosome instability. This telomerase-driven maintenance of telomere length acts as a lifeline for cancer cells, allowing them to escape the confines of normal cellular control mechanisms. While telomerase reactivation may seem advantageous for cancer cells, it's essential to recognize that telomeres also play an important role in maintaining genomic stability. Short telomeres trigger DNA damage responses, leading to cell cycle arrest or apoptosis. Telomere dysfunction can result in chromosomal fusions, deletions, and other genomic aberrations, the development of genetic mutations that may initiate cancer. Inhibiting telomerase could lead to telomere shortening, replicative senescence, and eventual cell death in cancer cells. While telomerase reactivation aids cancer cells in evading natural constraints, the dual nature of telomeres as protectors of genetic stability poses challenges to malignant transformation. The dynamic interplay between these factors underscores the complex landscape of cancer biology. Unraveling the intricacies of telomere maintenance and telomerase regulation not only enhances our understanding of cancer development but also holds the promise of innovative therapeutics. Drugs that target telomerase are being developed to inhibit its activity selectively in cancer cells, preventing telomere extension and limiting their proliferation potential. Therapies designed to induce telomere dysfunction or disrupt the shelterin complex (proteins that protect telomeres) are under investigation as potential cancer treatments. Combining telomere-targeted therapies with other treatment modalities, such as chemotherapy or immunotherapy, is being explored to enhance their effectiveness against cancer.