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Targeted inhibition of telomerase in human cancer: will it be a double-edged sword?
Abstract:
More than 80% of human malignancies express telomerase activity, while normal somatic tissues in general lack it. During each normal cell division, there is a constant loss of DNA sequences at chromosomal ends, which is due to the 'end-replication problem' of conventional DNA polymerase. Critical shortening of telomeres induces cell cycle arrest and eventually cell death. Telomerase, a ribonucleoprotein complex with a RNA (TR) and a catalytic subunit (TERT) as core components, is able to add reitineratedly telomeric repeat sequences to the very ends of chromosomes. It was suggested that activation of telomerase in tumor cells has a major impact on their continuous growth. Indeed, transfection of TERT constructs into various normal human cell types led to telomere elongation or stabilization and, most importantly, cellular immortalization. Conversely, inhibition of telomerase in tumor cell lines induced growth arrest, at least in first experimental settings. Such initial success implies that drug-mediated abrogation of telomerase action might be an ideal adjuvant treatment for cancer patients. There are, however, legitimate concerns about the generalization of such an approach.
Insights
Telomerase, an enzyme crucial for cancer cell growth, offers potential as an anti-cancer target. Inhibiting telomerase may halt tumor progression, but further research is needed to address potential side effects.
Area of Science:
- Molecular Biology
- Cancer Research
- Cell Biology
Background:
- Most human cancers (over 80%) exhibit telomerase activity, unlike normal somatic cells.
- Normal cell division leads to telomere shortening due to the 'end-replication problem', causing cell cycle arrest and death.
- Telomeres are protective DNA sequences at chromosome ends; their critical shortening limits cellular lifespan.
Purpose of the Study:
- To investigate the role of telomerase in cancer cell proliferation and immortalization.
- To evaluate the potential of telomerase inhibition as an anti-cancer therapeutic strategy.
- To explore the implications of telomerase activation and inhibition in cellular growth and cancer development.
Main Methods:
- Studied telomerase activity in human malignancies versus normal tissues.
- Utilized transfection of telomerase reverse transcriptase (TERT) constructs in normal human cell types.
- Examined the effects of telomerase inhibition in cancer cell lines.
Main Results:
- Telomerase, a ribonucleoprotein complex (RNA (TR) and catalytic subunit (TERT)), adds telomeric repeats to chromosome ends.
- TERT transfection led to telomere elongation, stabilization, and immortalization of normal human cells.
- Inhibition of telomerase in cancer cell lines resulted in growth arrest in initial experiments.
Conclusions:
- Telomerase activation is a key factor in the continuous growth of tumor cells.
- Targeting telomerase may offer a promising approach for adjuvant cancer therapy.
- Concerns exist regarding the broad application of telomerase inhibition strategies in cancer treatment.