Transregulation of microRNA miR-21 promoter by AP-1 transcription factor in cervical cancer cells

Area of Science:

• Oncology
• Molecular Biology
• Gene Regulation

Background:

• MicroRNA-21 (miR-21) is an oncogenic microRNA with altered expression in many cancers.
• Persistent Human Papillomavirus (HPV) infection drives cervical cancer and disrupts microRNA expression.
• The role of transcription factors in miR-21 dysregulation in cervical cancer requires further elucidation.

Purpose of the Study:

• To investigate the mechanism by which the Activator Protein-1 (AP-1) transcription factor activates miR-21 gene expression in cervical cancer cells.
• To identify the specific subunits of AP-1 involved in miR-21 regulation.

Main Methods:

• Reverse transcription quantitative polymerase chain reaction (RT-qPCR) and western blot assays to detect c-Fos and c-Jun expression.
• Electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) assays to analyze AP-1 binding to the miR-21 promoter.
• Reporter construct plasmids and immunofluorescence microscopy to confirm promoter activity and nuclear translocation of transcription factors.

Main Results:

• c-Fos and c-Jun proteins were confirmed to be expressed and regulate miR-21 expression in cervical cancer cells.
• AP-1 DNA-binding sites were identified in the human miR-21 promoter region.
• EMSA and ChIP assays demonstrated direct binding of AP-1, specifically c-Fos, to the miR-21 promoter in vivo, leading to increased miR-21 promoter activation.

Conclusions:

• The study demonstrates a physical interaction and functional cooperation between the AP-1 transcription factor and the miR-21 promoter.
• These findings provide a molecular explanation for the elevated miR-21 gene expression observed in cervical cancer cells.
• This mechanism highlights a potential therapeutic target for cervical cancer treatment.