A targeting modality for destruction of RNA polymerase I that possesses anticancer activity

Area of Science:

• Molecular Biology
• Cancer Research
• Drug Discovery

Background:

• Cancer cells exhibit altered ribosomal DNA (rDNA) transcription.
• Targeting RNA polymerase I (Pol I) is a promising strategy for cancer therapy.
• Understanding small molecule mechanisms of action is crucial for drug development.

Purpose of the Study:

• To investigate the anticancer activity and mechanism of action of a novel small molecule, BMH-21.
• To identify the molecular targets and pathways affected by BMH-21.
• To explore the therapeutic potential of BMH-21 in cancer treatment.

Main Methods:

• Screening of BMH-21 across NCI60 cancer cell lines.
• In vivo tumor growth inhibition studies.
• Analysis of BMH-21 binding to GC-rich DNA sequences.
• Assessment of RNA polymerase I (Pol I) transcription inhibition.
• Investigation of RPA194 protein levels and proteasome activity.

Main Results:

• BMH-21 exhibits broad and potent antitumorigenic activity in vitro and in vivo.
• BMH-21 binds to GC-rich sequences, primarily in ribosomal DNA genes.
• BMH-21 rapidly and potently represses RNA polymerase I (Pol I) transcription.
• BMH-21 induces proteasome-dependent degradation of RPA194, the catalytic subunit of Pol I.
• RPA194 degradation correlates with cancer cell killing.

Conclusions:

• BMH-21 is a potent anticancer compound targeting Pol I transcription.
• Proteasome-mediated control of RPA194 is a critical mechanism underlying BMH-21's activity.
• This study uncovers an unexpected therapeutic vulnerability in cancer cells, highlighting Pol I regulation as a novel drug target.