Targeting mitochondrial RNA polymerase for triple-negative breast cancer

Area of Science:

• Oncology
• Molecular Biology
• Cancer Metabolism

Background:

• Triple-negative breast cancer (TNBC) is aggressive with limited treatment options.
• Mitochondrial metabolism, specifically oxidative phosphorylation, is crucial for TNBC progression.
• Mitochondrial RNA polymerase (POLRMT) maintains mitochondrial function and oxidative phosphorylation.

Purpose of the Study:

• To investigate POLRMT as a therapeutic target in TNBC.
• To evaluate the efficacy of POLRMT inhibition strategies.

Main Methods:

• Kaplan-Meier survival analysis for POLRMT expression and prognosis.
• Analysis of The Cancer Genome Atlas (TCGA) for POLRMT transcript levels and promoter methylation.
• In vitro studies using siRNA, an inhibitor of mitochondrial transcription (IMT), and a mitochondrial protease targeting chimera (MtPTAC) to assess anti-TNBC activity.

Main Results:

• Elevated POLRMT levels correlate with poor prognosis in TNBC patients.
• POLRMT transcripts are upregulated in TNBC tissues, linked to promoter hypomethylation.
• POLRMT inhibition via siRNA, IMT, or MtPTAC suppressed TNBC cell proliferation, oxidative phosphorylation, and clonogenicity.
• MtPTAC selectively degraded POLRMT and inhibited growth in IMT-resistant cells.

Conclusions:

• POLRMT is a promising therapeutic target for TNBC.
• Targeting POLRMT disrupts critical metabolic pathways in TNBC.
• MtPTAC offers a novel strategy to overcome resistance to existing POLRMT inhibitors in TNBC treatment.