EGFR exon 19-deletion aberrantly regulate ERCC1 expression that may partly impaired DNA damage repair ability in...

Area of Science:

• Molecular Oncology
• DNA Damage and Repair Mechanisms
• Cancer Genomics

Background:

• Activating mutations in epidermal growth factor receptor (EGFR) are frequently linked to DNA damage repair (DDR) deficiencies.
• The precise molecular mechanisms underlying this association, particularly concerning EGFR exon 19 deletions, remain incompletely understood.
• Excision repair cross-complementation group-1 (ERCC1) is a critical protein in DNA nucleotide excision repair pathways.

Purpose of the Study:

• To investigate whether downstream signaling from EGFR exon 19 deletion mutations contributes to DDR deficiency.
• To determine if this contribution occurs via the downregulation of ERCC1 expression and function.
• To elucidate the role of EGFR downstream signals in regulating ERCC1 in EGFR mutant cells.

Main Methods:

• Comparative analysis of cell survival, DNA damage (γ-H2AX foci), and DNA repair (ERCC1, RAD51 foci) in EGFR exon 19 deletion versus wild-type cells.
• Treatment with a DNA cross-linking agent to assess cellular responses.
• Investigation of EGFR downstream signaling pathways' influence on ERCC1 expression (mRNA and protein) and function.

Main Results:

• EGFR exon 19 deletion cells exhibited increased γ-H2AX foci but impaired ERCC1 and RAD51 foci formation upon DNA cross-linker treatment.
• Inhibition of EGFR exon 19 deletion signals upregulated ERCC1 expression, while blocking wild-type EGFR signals downregulated it.
• EGFR exon 19 deletion downstream signals were found to inhibit ERCC1 expression and impair its foci formation in response to DNA damage.

Conclusions:

• Aberrant EGFR exon 19 deletion signaling is associated with reduced ERCC1 expression.
• This signaling also impairs ERCC1 recruitment to sites of DNA cross-link damage.
• These findings provide mechanistic insights into DDR deficiency observed in EGFR-mutant non-small cell lung cancer (NSCLC).