TELOMERE AND TELOMERASE: POTENTIAL TARGET FOR CANCER THERAPY

Telomerase is crucial for enabling the uncontrolled proliferation of cancer cells by maintaining telomere length, thus allowing them to bypass the 'Hayflick limit'.Telomerase is a multimeric ribonucleoprotein complex, consisting of a large number of subunits. The catalytic subunit, telomerase reverse transcriptase (TERT) and the template subunit, telomerase RNA component (TERC) are the two most important subunits of telomerase enzymes. The TERT protein is responsible for the synthesis of telomeric repeats from the template DNA located within TERC. This enzymatic activity is tightly regulated at multiple levels, including transcription, translation, and post translational modifications. Telomerase is active in 85%-90% of various cancer types but is absent in normal somatic cells, making it an attractive target for cancer therapy. Apart from its telomere lengthening property, telomerase has extra-telomeric functions independent of its catalytic activity which are related with metastasis and anti-apoptotic properties of cancer cells. Telomerase reverse transcriptase (hTERT) is involved in cancer cell migration and metastasis, although their interaction remains largely unexplored. Given that epithelial-to-mesenchymal transition (EMT) is a critical step in metastasis, targeting telomerase and EMT pathway is a promising approach to limit metastasis. Various telomerase inhibitors are giving promising result in clinical trial.