TERT promoter mutations in melanoma render TERT expression dependent on MAPK pathway activation

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Telomere maintenance is crucial for cancer cell immortality.
• Telomerase re-activation in cancer was poorly understood.
• TERT promoter mutations were recently discovered in various cancers.

Purpose of the Study:

• To investigate the mechanism of TERT gene re-expression in melanoma.
• To elucidate the link between TERT promoter mutations and MAPK pathway activation.

Main Methods:

• Analysis of TERT expression in melanoma cell lines.
• Investigation of transcription factor binding to the mutated TERT promoter.
• Assessment of ETS1 phosphorylation and its role in TERT regulation.
• Inhibition of ETS1 to determine its effect on TERT expression.

Main Results:

• TERT promoter mutations create ETS transcription factor binding sites.
• Melanoma cell lines with oncogenic BRAF or NRAS mutations show MAPK pathway activation.
• Activated MAPK pathway leads to ETS1 phosphorylation and binding to the mutated TERT promoter.
• ETS1 binding drives TERT re-expression; ETS1 inhibition reduces TERT expression.

Conclusions:

• TERT promoter mutations directly link MAPK pathway activation to TERT gene re-expression in melanoma.
• The transcription factor ETS1 is a key mediator in this process.
• This mechanism provides insight into telomerase reactivation in cancer.