A novel HER2 gene body enhancer contributes to HER2 expression

Area of Science:

• Molecular Biology
• Epigenetics
• Cancer Research

Background:

• Transcriptional regulation of human epidermal growth factor receptor-2 (HER2) is crucial for breast cancer progression and therapy resistance.
• Epigenetic mechanisms, including histone modifications like H3K4me3 and H3K9ac, are known to regulate HER2 transcription, primarily at the promoter region.

Purpose of the Study:

• To identify novel epigenetic regulatory elements involved in HER2 transcription.
• To investigate the role of these elements in HER2-positive, HER2-low, and HER2-negative breast cancers, particularly in response to therapy.

Main Methods:

• Identification and characterization of a novel enhancer element within the HER2 gene body.
• Analysis of histone modification marks associated with enhancer activity.
• Investigation of transcription factor binding (TFAP2C) to the novel enhancer.
• Assessment of DNA methylation patterns within the enhancer region and their correlation with HER2 expression.

Main Results:

• A novel HER2 gene body enhancer (HGE) was identified, located within introns 19-22.
• HGE exhibits enhancer histone modification marks and enhances HER2 promoter activity.
• TFAP2C binds to HGE and is essential for its enhancer function.
• DNA methylation in HGE inversely correlates with HER2 expression in breast cancer samples.

Conclusions:

• The discovery of HGE provides new insights into the epigenetic regulation of HER2 transcription.
• HGE plays a significant role in controlling HER2 expression, impacting tumorigenesis and therapeutic responses in various breast cancer subtypes.
• Targeting HGE may offer novel therapeutic strategies for breast cancer.