Telomeres, telomerase, and myc. An update

Area of Science:

• Cellular biology
• Molecular oncology
• Genetics

Background:

• Normal human somatic cells undergo senescence, a finite lifespan, due to mechanisms including p53/pRb activation and telomere shortening.
• Cancer cell development requires circumventing these senescence triggers.
• Telomerase, composed of telomerase RNA (TR) and telomerase reverse transcriptase (TERT), counteracts telomere shortening.

Purpose of the Study:

• To investigate the role of telomerase, specifically human TERT (hTERT), in overcoming cellular senescence and enabling cancer cell proliferation.
• To explore the potential involvement of oncogenes like c-myc in telomerase reactivation within tumor development.

Main Methods:

• Analysis of telomerase components (TR and hTERT) in human cancers and cell lines.
• Investigating the effect of ectopic hTERT expression on telomere length and cell proliferation in mortal human cells.
• Examining the role of c-myc in regulating telomerase activity and telomere stabilization.

Main Results:

• The majority of human cancers express telomerase, with hTERT identified as the rate-limiting component for activity.
• Ectopic hTERT expression in normal cells leads to telomere elongation, permanent growth, and increased susceptibility to transformation.
• c-myc overexpression may reactivate telomerase, stabilize telomeres, and promote continuous proliferation, suggesting a potential cancer cell strategy.

Conclusions:

• hTERT-mediated telomere maintenance is crucial for immortalization and potentially cancer development.
• Oncogenic deregulation, such as c-myc overexpression, can drive telomerase reactivation as a mechanism for escaping senescence.
• While telomerase reactivation is a key strategy, alternative pathways for cancer cell immortalization may also exist.