DNA damage transiently increases TRF2 mRNA expression and telomerase activity

Area of Science:

• Molecular Biology
• Cell Biology
• Cancer Research

Background:

• Telomerase is crucial for maintaining telomere length.
• DNA damage can trigger cellular responses, including apoptosis and cell cycle arrest.
• The role of telomerase and telomere-binding proteins in DNA damage response is not fully understood.

Purpose of the Study:

• To investigate the effect of etoposide, a topoisomerase II inhibitor, on telomerase activity in cancer cells.
• To explore the mechanism of etoposide-induced telomerase activation.
• To examine the expression of telomere-binding proteins TRF1 and TRF2 in response to DNA damage.

Main Methods:

• Treatment of HL60 and other cell lines with etoposide.
• Quantitative assessment of telomerase activity.
• Analysis of hTERT mRNA and TRF1/TRF2 mRNA expression.
• Correlation analysis with DNA damage and cell cycle status.

Main Results:

• Etoposide treatment caused a transient, reversible increase in telomerase activity in multiple cell lines.
• Telomerase activation correlated with DNA damage but not cell cycle arrest.
• No transcriptional upregulation of hTERT mRNA was observed, indicating post-transcriptional regulation.
• TRF2 mRNA expression was upregulated early and reversibly, while TRF1 mRNA levels remained unchanged or increased in G2/M phase.

Conclusions:

• DNA damage, induced by etoposide, activates telomerase post-transcriptionally in malignant cells.
• Upregulation of telomerase activity and TRF2 expression may serve as anti-apoptotic mechanisms.
• TRF2 upregulation by DNA damage could potentially counteract senescence signals from shortened telomeres.