A Novel ATM Antisense Transcript ATM-AS Positively Regulates ATM Expression in Normal and Breast Cancer Cells

Area of Science:

• Molecular Biology
• Cancer Genetics
• Epigenetics

Background:

• The ataxia telangiectasia mutated (ATM) gene is vital for DNA damage response and its dysregulation is common in breast cancer.
• The precise mechanisms governing ATM expression in cancer remain incompletely understood.
• Bioinformatic analysis predicted a novel antisense transcript, ATM-antisense (AS), originating from the ATM gene locus.

Purpose of the Study:

• To identify and characterize the predicted ATM-AS transcript.
• To investigate the regulatory role of ATM-AS in ATM gene expression.
• To explore the functional significance of ATM-AS in breast cancer biology and patient prognosis.

Main Methods:

• Verification of ATM-AS using single strand-specific RT-PCR.
• Quantification of ATM-AS and ATM expression via qRT-PCR and Western blotting in cell lines and tissues.
• Functional assays including luciferase reporter assays, mass spectrometry, ChIP-qPCR, and RIP to elucidate regulatory mechanisms.
• Assessment of DNA damage repair via immunofluorescence and HCR assays.
• Correlation analysis of ATM-AS levels with ATM expression and patient prognosis in breast cancer tissues.

Main Results:

• ATM-AS was identified and found to be upregulated in breast cancer.
• ATM-AS positively regulates ATM gene expression by recruiting KAT5 histone acetyltransferase to the ATM promoter.
• Reduced ATM-AS levels impaired ATM-mediated DNA damage repair in vitro.
• ATM-AS expression positively correlated with ATM expression and improved patient prognosis in breast cancer tissues.

Conclusions:

• ATM-AS is a novel, essential positive regulator of ATM expression, functioning via KAT5 recruitment to the ATM promoter.
• This study reveals a new mechanism for ATM gene dysregulation in breast cancer.
• The findings enhance understanding of how antisense transcripts regulate their host genes and impact cancer outcomes.